Fruit & Vegetable Fertiliser | Organic Plant Food 4-5-6
A balanced 4-5-6 feed for fruit and veg.
from £11.50
Rose & Shrub Fertiliser — 5-3-5 NPK, Made with Organic Ingredients
5-3-5 NPK
Premium Organic Blend
Dual Fast & Slow Release
British Handcrafted
Full Ingredient Transparency
Compostable Packaging
Dr Forest Rose & Shrub Fertiliser is a slow-release organic coarse powder handcrafted in Stockport, Greater Manchester, for roses and flowering shrubs — hydrangeas, camellias, rhododendrons, azaleas and the deciduous shrubs that carry the summer garden. The 5-3-5 NPK ratio balances vigorous cane and stem growth with the sustained potassium supply needed for bloom production, colour intensity, fragrance and repeat performance across a full season — without the high-nitrogen excess that pushes leafy growth at the expense of flowers.
From first bud break in March to the final autumn flush — premium organic ingredients working across the full season. Fermented biochar and EM microorganisms improve soil biology permanently with every application. Yorkshire Polyhalite delivers four nutrients simultaneously from a single North Yorkshire mineral. Alfalfa Meal contributes triacontanol, the natural compound prized by rose growers for its effect on bud count and fragrance intensity. The blend is pH-neutral, so it feeds acid-loving shrubs such as camellias and rhododendrons without liming the soil they sit in. This is a fertiliser that improves the soil it feeds, not just the plants above it.
What it does for roses and flowering shrubs
More Blooms, Bigger Blooms
Balanced N and K at 5% each sustains both the vegetative structure and the bloom production demand simultaneously — the combination that produces a well-clothed, floriferous rose
Stronger Fragrance
Chloride-free potassium and triacontanol from Alfalfa Meal increase terpenoid and benzenoid synthesis — the volatile compounds responsible for the scent that distinguishes a great rose from an adequate one
Longer Vase Life
Calcium from Gypsum and Polyhalite builds cell wall rigidity in petals — thicker, more substantial flowers that hold their form longer in the garden and after cutting
Deeper, Richer Colour
Chloride-free K drives anthocyanin synthesis — the pigments responsible for red and pink depth in roses and in shrub flowers alike. No muriate of potash anywhere in the formula
Induced Resistance
Chitin is recognised by receptors in the plant cell membrane and primes the plant's own Systemic Acquired Resistance pathway — salicylic acid signalling and defence gene expression are raised before any challenge arrives. Silica Meal adds physical cell wall reinforcement. This is the plant's own response, not an applied treatment
Suits Acid-Loving Shrubs
Calcium comes from gypsum, which is pH-neutral — it supplies Ca without raising soil pH the way lime does. That makes the blend usable on camellias, rhododendrons, azaleas and hydrangeas as well as on roses
A Richer Soil Every Year
Fermented Biochar, EM microorganisms and humic acid build permanent soil biology — each application improves the rhizosphere for the seasons that follow
Why 5-3-5 for roses and shrubs?
Unlike fruiting plants that benefit from a high K:N ratio (2:1 or more), roses and flowering shrubs simultaneously produce substantial vegetative structure — canes, stems, laterals, leaves — and flowers across a long season. Equal N and K at 5% provides the balanced support for both. Phosphorus is intentionally modest at 3%: established woody plants have deep root systems and do not need high P, and excess phosphorus in the slightly acidic soils roses and most flowering shrubs prefer can interfere with micronutrient uptake. It is also the reason a low-P blend is the sensible choice around hydrangeas. This is a formula calibrated for how these plants actually grow — not derived from a general-purpose template.
Feeding hydrangeas — an honest note on blue
The 5-3-5 ratio suits general flowering-shrub feeding, and it suits pink and white hydrangeas well. Blue is a different question, and it is worth being plain about it. Blue hydrangea colour depends on acidic soil and on aluminium being present in a plant-available form — it is not something an NPK ratio delivers. Phosphorus is the classic antagonist: it binds aluminium in the soil and takes it out of circulation, which is the usual reason blueing fails on a high-phosphorus feed. At 3% P this blend is modest and will not work against you. But if blue flowers are the goal, the limiting factor is your soil pH, not your fertiliser. Bring pH down with our Sulphur Soil Acidifier, and see the full hydrangea and ericaceous range. This product feeds the plant; it does not change flower colour, and we do not claim that it does.
Ingredients — What They Are and Why
Every ingredient contributes a specific, research-backed function. The formula combines traditional organic inputs — long proven by rose growers — with premium regenerative ingredients that permanently improve soil biology. No fillers. Nothing inert.
Nitrogen Plant Extract
🇬🇧 Cambridgeshire · Plant-derived · Controlled release
The primary nitrogen carrier — plant-derived, mineralising through microbial protease activity over 6–8 weeks. At 5% N in the finished formula, the rate supports vigorous cane extension and dense, dark foliage without triggering the sappy, chlorotic new growth that excess N creates and that rose pathogens exploit. Also contributes phosphorus and potassium in organic form as it breaks down.
Sørensen, 1998 — plant-derived N mineralisation rates in horticultural soils
Yorkshire Polyhalite
🇬🇧 North Yorkshire · 50–60 day release
Mined 1,200m below the North Sea — a unique four-nutrient mineral delivering 14% K₂O, 17% CaO, 6% MgO and 48% SO₃ simultaneously. The 50–60 day release rate provides sustained secondary nutrition through the mid and late season when successive flushes of bloom create the highest simultaneous demand for K, Ca and Mg. Entirely chloride-free — no muriate of potash, no chloride suppression of fragrance pathways.
Johnston & Dawson, 2018 — polyhalite agronomic performance in horticultural crops
Sulphate of Potash
🪨 Mineral · Immediate release
50% K₂O in immediately plant-available sulphate form — entirely chloride-free. Activates stomatal regulation, sugar transport to developing buds, anthocyanin pigment synthesis and cell wall construction from day one of application. Bridges the gap before Yorkshire Polyhalite's slower K release builds. The chloride-free sourcing is non-negotiable for preserving fragrance pathway chemistry in roses.
Zörb et al., 2014 — chloride effects on secondary metabolite synthesis in ornamentals
Gypsum (Calcium Sulphate)
🪨 Mineral · Immediate release
23.3% Ca and 18.6% S both immediately available as sulphate. Calcium is a structural component of cell walls — adequate Ca means thicker petals, stronger stems, longer vase life and significantly reduced petal drop in garden roses and cut stems. pH-neutral: unlike lime, gypsum supplies calcium without raising soil pH, making it safe across the full 6.0–7.0 range that roses prefer.
Bangerth, 1979 — calcium supply and cell wall development in ornamental flowers
Alfalfa Meal
🌿 Plant-based · Biostimulant
The standout ingredient for rose performance. Alfalfa Meal contains triacontanol — a natural plant growth regulator specifically studied in rose cultivation. Research shows triacontanol increases bud count, extends stem length and elevates secondary metabolite production including the terpenoid and benzenoid fragrance compounds. Long used by specialist rose growers; this formula incorporates it as a core ingredient rather than an add-on.
Ries & Houtz, 1983 — triacontanol as a plant growth regulator · Albrecht, 2010 — alfalfa in rose cultivation
Mealworm Frass
🌿 Sustainably reared · SAR activator
Contains chitin, which triggers Systemic Acquired Resistance — priming the rose's own defences against the three diseases most destructive to the genus: black spot (Diplocarpon rosae), powdery mildew (Podosphaera pannosa) and grey mould (Botrytis cinerea). Plants with active SAR mount faster, stronger responses to fungal attack, reducing infection severity without fungicide use. Also supplies background N and trace minerals as it mineralises.
Fransen et al., 2020 — chitin-induced SAR in ornamental crops
Silica Meal
🪨 Mineral · Structural
Silicon deposited in cell walls adds rigidity without brittleness. For roses this means canes and pedicels that carry heavy blooms without drooping, and a physical barrier at the cell wall against fungal hyphal penetration. Silica is rarely present at adequate concentrations in UK garden soils — it must be supplied. The reinforced cell walls also reduce entry points for aphid stylet insertion, which is particularly relevant in roses where soft new growth in spring is the primary aphid target.
Epstein, 1999 — silicon in plant biology and disease resistance
Seaweed Meal
🌿 Biostimulant · Trace minerals
Provides cytokinins that delay petal and leaf senescence — extending the display period of individual rose flushes. Betaines improve osmotic adjustment under drought stress, maintaining bloom production through dry spells. Mannitol acts as a carbon source for beneficial rhizobacteria. Natural auxins drive lateral root branching, improving the nutrient and water uptake capacity needed to sustain successive flushes of bloom on repeat-flowering varieties.
Craigie, 2011 — seaweed biostimulants: mode of action and agronomic performance
Basalt Rock Dust
🪨 Volcanic mineral · Slow release
Remineralises soils with a broad spectrum of silicate-bound trace elements including iron, manganese, zinc, copper and boron — the micronutrients most consistently deficient in managed UK garden soils after years of crop removal without adequate replacement. Basalt dissolves slowly through the action of soil acids and microbial activity, providing a long-term trace mineral reserve. Also improves soil structure by adding fine mineral particles that increase cation exchange capacity.
Leonardos et al., 1987 — rock powders and soil remineralisation in horticultural systems
Clay Minerals
🇬🇧 British · CEC reservoir
High cation exchange capacity — binds and slowly releases K, Ca and Mg between waterings. Particularly valuable for roses in containers or on light, sandy soils where nutrient leaching is the primary cause of mid-season deficiency and mid-season colour fade. Also improves water-holding capacity around the root zone, which is critical for roses in dry summers when erratic soil moisture disrupts the transpiration stream and causes calcium delivery failures.
Sposito, 2008 — cation exchange in clay minerals and plant nutrition
Fermented Biochar
🌿 British · Permanent soil benefit
British-sourced biochar fermented with EM microorganisms before blending — pre-colonised with beneficial microbial populations that establish more rapidly in the root zone. Creates a permanent porous mineral scaffold in the rhizosphere that retains water and nutrients between applications. Unlike organic matter, biochar does not decompose — every application deposits permanent infrastructure. Increases plant-available K retention by 18–35% under leaching conditions, which is directly relevant for container roses.
Lehmann et al., 2011 — biochar and K retention in horticultural substrates
EM Microorganisms
🌿 Living culture · Rhizosphere biology
Effective Microorganisms — a consortium of beneficial bacteria, yeasts and lactic acid bacteria — suppress pathogenic microorganisms through competitive exclusion, accelerate organic matter breakdown and produce bioactive compounds that promote root growth. In roses specifically, EM application consistently improves secondary metabolite production — the fragrance and colour compounds that distinguish a well-grown rose. The living culture is incorporated at blending to activate the fermented biochar.
Higa & Parr, 1994 — Effective Microorganisms and sustainable agriculture
Humic & Fulvic Acid
🌿 Mineral organic · Chelation
Chelates micronutrients — particularly iron and manganese — maintaining them in plant-available form across the slightly acidic pH that roses prefer, where these elements can become locked up in unavailable forms. Increases root proton pump activity and overall nutrient uptake efficiency. Research shows humic acid increases total soil bacterial biomass by 30–60% and stimulates mycorrhizal colonisation by 25–40% — creating a progressively more biologically active rhizosphere with each application.
Nardi et al., 2009 · Zandonadi et al., 2010
Directions for Use
Rates are calibrated for the 5-3-5 NPK formula and apply to roses and to flowering shrubs alike. All g/m² rates assume even surface distribution over the full root zone with light incorporation to 2–3cm depth. For new plantings or beds being prepared for the first time, apply at double the standard rate and work into the full planting depth before setting the plants in.
How to Apply
1
Water first
Soil should be moist before applying. If the soil is very dry, water thoroughly and allow to drain for 30 minutes. Never apply to bone-dry soil — the mineral fraction requires moisture to dissolve and begin moving into the root zone.
2
Sprinkle around the drip line
Distribute evenly around the full root zone — apply from approximately 10cm out from the base canes or stems to the drip line of the canopy. Do not apply directly against the stem base. For climbing roses, distribute along the full length of the root run rather than concentrating at the plant base. On broad shrubs such as hydrangeas and rhododendrons the feeder roots sit under the outer half of the canopy, so work outwards to the drip line rather than mounding at the crown.
3
Lightly fork in
Gently incorporate to 2–3cm depth using a hand fork or border hoe. Avoid deep cultivation around roses — the fibrous feeder roots are concentrated in the top 15cm and are easily damaged. Rhododendrons, azaleas and camellias are shallower still and resent forking, so on these scatter over the surface and let the mulch and rain take it down. Light surface incorporation is all that is needed.
4
Water in thoroughly
Water within 24 hours of application. Apply before forecast rain when possible — it removes the need to water and ensures even penetration. In containers, water until it runs freely from the base to distribute the mineral fraction through the full root zone.
Rates — Garden Roses & Flowering Shrubs
| Rose or Shrub Type | Rate per m² / plant | Applications per Season | Timing |
|---|---|---|---|
| Hybrid Tea roses | 80–100g per m² | 3–4 applications | Late March · late May · late June · early August (stop after early August) |
| Floribunda roses | 80–100g per m² | 3–4 applications | Late March · late May · late June · early August (stop after early August) |
| Shrub roses (incl. English roses) | 80–100g per m² | 3 applications | Late March · June · late July (stop after late July for most shrubs) |
| Climbing roses | 90–110g per m² | 3–4 applications | Late March · late May · late June · early September (wall warmth extends hardening) |
| Rambling roses | 80–90g per m² | 2 applications | Late March · immediately after flowering (July–August). Once-blooming — no mid-season feed needed. |
| Miniature roses | 50–65g per m² | 3–4 applications | Late March · May · July · early August. Lower rate due to smaller root zone. |
| Ground cover roses | 70–80g per m² | 2–3 applications | Late March · June · (optional) early August for repeat-flowering varieties |
| Hydrangea — mophead & lacecap (H. macrophylla) | 80–100g per m² | 2–3 applications | Late March · June. Stop after June — these flower on last year's wood and need the summer to ripen it. |
| Hydrangea — paniculata & arborescens | 80–100g per m² | 2–3 applications | Late March · late May · (optional) late June. These flower on current-season wood, so early feeding does the work. |
| Camellia | 80–100g per m² | 2–3 applications | Late March · after flowering (May–June). The post-flowering feed supports next year's bud set. |
| Rhododendron & azalea | 80–100g per m² | 2–3 applications | Late March · immediately after flowering (May–June). Scatter on the surface — do not fork in over shallow roots. |
| Deciduous flowering shrubs (philadelphus, weigela, buddleja, spiraea) | 80–100g per m² | 2–3 applications | Late March · June · late July for late-flowering shrubs. Spring-flowering shrubs: feed again straight after flowering. |
| Lilac, viburnum & other woody shrubs | 80–100g per m² | 2–3 applications | Late March · June. Established specimens are generally content with the March feed alone. |
Rates — Containers & Pots
| Situation | Initial Charge | Top-Dress | Notes |
|---|---|---|---|
| Pots & containers | 3–4g per litre of compost | 2g per litre · every 4 weeks | Mix the initial charge evenly through the full compost volume before planting. 3g/L for compost already containing slow-release nutrients; 4g/L for plain or peat-free mixes. |
| Standard rose or shrub pot (15–20L) | 45–80g | 30–40g · every 4 weeks | Apply around the inner perimeter of the pot, not mounded at the stem base. The same applies to potted hydrangeas, camellias and patio shrubs. |
New Plantings — Soil Preparation
| Situation | Rate | Method |
|---|---|---|
| Bed preparation (pre-planting) | 100–140g per m² | Fork into the top 15–20cm before planting. This charges the root zone before the plant goes in — particularly important in rose beds and shrub borders that have not been fed for several seasons. |
| Individual planting hole | 30–50g per plant | Mix into the soil removed from the planting hole before backfilling. Do not place fertiliser in direct contact with the roots — mix thoroughly with soil first. |
Soil pH
Roses prefer pH 6.0–7.0. Below 6.0, check with lime; above 7.5, consider elemental sulphur or ericaceous mulch. Do not over-lime — soil pH above 7.5 locks up iron and manganese.
Ericaceous shrubs
Camellias, rhododendrons, azaleas and hydrangeas want a lower pH than roses — around 5.0–6.0. This blend is pH-neutral and will not push soil pH up, but it is a feed rather than an acidifier. If your soil is alkaline, correct the pH separately with our Sulphur Soil Acidifier.
Soil temperature
Organic N fractions mineralise above 8°C soil temperature — typically mid-to-late March in most UK gardens. The mineral K and Ca fractions activate from day one regardless of soil temperature.
Stop date
Mid-August for most roses. Late feeding produces soft cane growth that does not harden before frosts. Climbing roses on warm south-facing walls can be fed until early September. Flowering shrubs are best stopped earlier still — mophead and lacecap hydrangeas after their June feed, so the wood ripens.
Signs of overfeeding
Very dark, lush foliage with reduced flowering; soft sappy new shoots that attract aphids; excessive vegetative growth at the expense of buds. Halve the rate at the next application.
Signs of underfeeding
Pale yellow-green foliage; slow cane extension; smaller buds than previous years; interveinal yellowing on older leaves (likely magnesium deficiency). Apply at the upper end of the rate range.
Safety
Safe for children, pets, beneficial insects and wildlife at recommended rates. Wash hands after use. Do not apply to waterlogged soil or immediately before heavy rain.
Growing Roses & Flowering Shrubs — A Guide for New Growers
Roses have a reputation for being difficult, and flowering shrubs a reputation for looking after themselves. Neither is quite right. In practice the basics are straightforward — and understanding them makes the difference between a plant that survives and one that thrives. This guide covers the main rose types, the flowering shrubs most often grown alongside them, the seasonal feeding rhythm, and what to watch for through the year.
Rose Types — Which One Do You Have?
Roses fall into a small number of groups with meaningfully different growing habits. Knowing your type helps you feed and prune at the right time. Flowering shrubs are covered in the section below this one.
Hybrid Tea
Classic large-flowered bush rose · Repeat-flowering
The traditional garden rose — upright bushes typically 90–150cm tall with large, high-centred blooms on long stems, one flower per stem. Varieties include Peace, Mister Lincoln, Elina, Just Joey. Highly bred, somewhat disease-susceptible, but produces the finest individual flowers. Needs 3–4 feeds per season. Hard prune in late February.
Floribunda
Cluster-flowered bush rose · Repeat-flowering
Similar habit to hybrid teas but producing clusters of smaller flowers rather than single large blooms — giving a more continuous display with less gap between flushes. Varieties include Iceberg, Amber Queen, Sexy Rexy, Queen Elizabeth. Generally more disease-resistant than hybrid teas. Needs 3–4 feeds. Prune as hybrid teas but slightly less hard.
Shrub Rose / English Rose
Larger, more relaxed habit · Most repeat-flower
A broad category including David Austin English roses (Gertrude Jekyll, Graham Thomas, Olivia), traditional shrub roses and species hybrids. Typically larger than bush roses (1.2–2.0m), with a more natural, arching habit and flowers in the old-fashioned cupped or quartered style. Generally good disease resistance. Needs 3 feeds. Prune lightly — reduce by one third in late February.
Climbing Rose
Long, stiff canes for training · Most repeat-flower
Produces long, stiff canes (1.8–4m+) that must be tied in to a support — wall, trellis, arch or pergola. Most modern climbers repeat-flower well. Varieties include Compassion, New Dawn, Climbing Iceberg, Generous Gardener. Train main canes horizontally or at an angle — this triggers lateral shoots that carry the flowers. Feed 3–4 times per season. Prune lightly in winter, cutting flowered laterals back to 2–3 buds.
Rambling Rose
Long, flexible canes · Flowers ONCE in summer
Ramblers produce very long, flexible canes (4–8m) covered in clusters of smaller flowers — typically in June–July — and do not repeat. Varieties include Rambling Rector, Paul's Himalayan Musk, Veilchenblau, Seagull. Excellent for covering large structures, arches and trees. Only 2 feeds needed (March and after flowering). Prune immediately after flowering by cutting flowered canes to the base — the new canes growing this year will flower next summer.
Miniature Rose
Compact (30–60cm) · Repeat-flowering
Small plants with proportionally scaled flowers — ideal for containers, patio edges and windowboxes. Generally very disease-resistant and free-flowering. Feed at lower rates (50–65g/m²) every 4–5 weeks. Particularly good in pots where the contained root zone benefits from the biochar component's improved nutrient retention.
Ground Cover Rose
Wide-spreading, low habit · Often repeat-flowers
Wide, low-growing roses (30–60cm tall, spreading 1.2–2.0m) used to cover banks, suppress weeds and fill large spaces. Varieties include Surrey, Flower Carpet, Bonica. Generally very disease-resistant. Light pruning — trim annually with shears rather than careful individual cutting. 2–3 feeds per season at slightly lower rates than upright roses.
Standard Rose
Grafted onto a tall stem · Repeat-flowering
Any of the above rose types grafted onto a single upright stem (60–120cm), producing a lollipop-shaped plant. The rose type determines feeding requirements — treat the canopy as you would the equivalent bush or shrub rose. Standard roses in containers need careful attention to watering and feeding as the elevated head is vulnerable to wind and the restricted root zone dries quickly.
Flowering Shrub Types — Feeding and Habit
Flowering shrubs divide most usefully by where the flowers come from. A shrub that flowers on wood made last year needs its feeding finished early enough for that wood to ripen; a shrub that flowers on this year's growth can be fed later. Get that one distinction right and the rest follows.
Hydrangea — Mophead & Lacecap
H. macrophylla · Flowers on last year's wood
The familiar round-headed and flat-headed hydrangeas, 1–2m, flowering July to September. They set next year's buds in late summer, so feeding must finish early enough for the wood to ripen — a March feed and a June feed is the whole programme. Leave the faded heads on over winter as frost protection and cut back to the first fat pair of buds in early spring. Flower colour is governed by soil pH and aluminium availability, not by the feed; see the note on blue below.
Hydrangea — Paniculata & Arborescens
Cone and dome heads · Flowers on this year's wood
Varieties such as Limelight, Vanille Fraise and Annabelle. Because they flower on current-season growth they can be pruned hard in early spring and will still flower the same summer — which also makes them the more forgiving hydrangeas for a cold or exposed garden. Feed at bud break and again in late May to build the growth that will carry the flowers. Their colour is white through to green and pink as they age and is not pH-dependent, so soil acidity is not a factor here.
Camellia
Evergreen · Acid soil · Flowers late winter to spring
Glossy evergreen shrubs flowering from February to May, before most of the garden has started. Next year's buds are set in mid-summer, which makes the feed straight after flowering the important one — and makes summer watering important too, since drought in July is the usual cause of bud drop the following spring. They want an acid soil, pH 5.0–6.0. This blend is pH-neutral and will not lime the ground beneath them. Site out of early morning sun so frosted buds thaw slowly.
Rhododendron & Azalea
Shallow-rooted · Acid soil · Spring flowering
Both belong to the genus Rhododendron — azaleas are simply the smaller, often deciduous members of it. The roots are fine and sit in the top few centimetres, so scatter feed on the surface and never fork it in. Feed at bud break and again immediately after flowering. Mulch with composted bark or leaf mould to keep the root zone cool and damp. On alkaline soil they will yellow between the leaf veins whatever you feed them, and the fix is soil pH rather than fertiliser.
Deciduous Flowering Shrubs
Philadelphus, weigela, spiraea, deutzia · Flowers on last year's wood
The workhorses of the mixed border. Nearly all of them flower on stems made the previous year, which gives one simple rule: prune immediately after flowering, taking a third of the oldest stems to the base, and feed at the same time so the plant has what it needs to build next year's flowering wood. A feed at bud break in late March and a second after flowering covers a mature shrub comfortably.
Buddleja & Late-Summer Shrubs
Flowers on this year's wood · Hard spring pruning
Buddleja, hardy fuchsia, caryopteris, perovskia and the like flower on growth made in the current season, so they are cut hard back in March and rebuild from the base each year. That is a large amount of growth to make in a short season, and it is the one group where a July feed genuinely earns its place. Buddleja in particular will flower on poor ground but flowers far better with a fed root zone.
Blue hydrangeas — where the colour actually comes from
Mophead and lacecap hydrangeas turn blue when the soil is acidic — roughly pH 5.5 and below — and aluminium is present in a form the roots can take up. Above that, the same plant flowers pink. White varieties stay white whatever you do. Phosphorus is the antagonist in this: it binds aluminium into insoluble compounds and takes it out of reach, which is why a high-phosphorus feed is the usual reason blueing fails. At 3% P this blend is modest and will not obstruct you, but it is a fertiliser, not a colourant, and it will not turn a pink hydrangea blue on its own. If blue is the goal, the work is in the soil: lower the pH with our Sulphur Soil Acidifier and keep it there, and see the hydrangea and ericaceous range for the rest.
The Seasonal Feeding Calendar
Timing matters as much as rate. The calendar below is built around roses, which have the longest feeding season of anything in this group; the notes say where flowering shrubs and hydrangeas step off it.
| Month | What the Plant is Doing | Feeding Action | Notes |
|---|---|---|---|
| January–February | Dormant. No leaf, minimal root activity. | Do not feed. | Use this time to prune (late February for most), clear old mulch, and check for overwintering pests and disease debris. Apply a fresh mulch of well-rotted compost after pruning. Leave last year's hydrangea heads on until the worst frosts have passed — they shelter the buds beneath them. |
| Late March | First red buds breaking. Root activity resuming. | First feed of the season. | The trigger is bud break — visible red buds emerging from the canes. Apply around the drip line at the full season rate. This is the most important application of the year — it charges the root zone before the main growth flush begins. Flowering shrubs, hydrangeas included, take their first feed at the same point. |
| April–May | Rapid cane and leaf extension. Bud initiation. | No feed needed if late March was done. | Watch for aphids on soft new growth — the chitin in Mealworm Frass will be priming SAR responses but this takes a few weeks. A seaweed liquid spray (not this product) can boost the SAR activation. Check soil moisture and water deeply if dry. |
| Late May | Buds swelling. First flush approaching. | Second feed (4–5 weeks after March). | Critical timing — nutrients applied now will be available in the flower itself. This application directly determines bloom size, petal substance and fragrance intensity in the first flush. Do not skip this one. Hydrangea paniculata and arborescens take their second feed here, since they flower on the growth they are making now. |
| June | Main flush flowering. Deadheading begins. | No feed during peak flowering. | Deadhead spent flowers promptly — removing the developing hip redirects the plant's energy from seed production back to bud initiation. On ramblers, note which canes are carrying flowers this year: these will be removed after flowering, not next spring. |
| Late June | First flush ending. New basal shoots emerging. | Third feed (4–5 weeks after May). | This feed sustains the new basal shoots — the strong new canes from the base of the plant — which will carry next year's best flowers. It also initiates the second flush of bloom in repeat-flowering varieties. Ramblers: feed immediately after flowering instead. Mophead and lacecap hydrangeas: this is their last feed of the year, so the wood ripens before autumn. |
| July | Second flush developing. New canes extending. | No feed unless 5 weeks since last application. | A hot, dry July can cause stress — water deeply at the base rather than splashing foliage. Fungal diseases spread rapidly in humid conditions; ensure good airflow around the plant and remove any heavily infected leaves at the compost bin, not the compost heap. |
| Early August | Peak repeat-flowering. Late basal shoots. | Fourth feed (optional — for repeat-flowering roses only). | This is the last feed of the season for most garden roses. It sustains the late summer and early autumn flowering. Once-blooming roses (ramblers, some old garden roses) do not need this application, and neither do flowering shrubs — they should already have finished. |
| Mid-August onwards | Late season flushes. Canes beginning to harden. | Stop all feeding. | Late feeding is one of the most common mistakes with roses, and with shrubs it is worse — a hydrangea that goes into autumn with soft, unripened wood loses next year's flower buds to the first hard frost. Late feeding produces growth that cannot harden before the first frosts, and that frost-killed growth provides entry points for disease and dieback. Let the plant transition naturally into autumn dormancy from mid-August. |
| September–November | Last flushes. Hips developing. Leaves yellowing. | Do not feed. | Some roses produce attractive hips in autumn — if you want these, stop deadheading in September and let the last flowers set fruit. Clear fallen leaves promptly as they can harbour black spot spores. Do not compost infected leaves. |
| December | Dormant. | Do not feed. | A good time to order bare-root roses and bare-root shrubs for planting in January–March. Bare-root stock is the best-value way to build a rose garden or a shrub border — it establishes faster than containerised plants and is significantly cheaper. |
Key Principles for New Rose and Shrub Growers
Deadhead promptly
On roses, remove spent flowers before the hip swells — each hip that forms uses energy the plant could direct to the next flush of buds. Cut back to the first outward-facing leaf with 5 leaflets. Mophead and lacecap hydrangeas are the exception: leave the faded heads on through winter and remove them in early spring.
Water deeply, not often
Roses need water at depth — roots grow to 45–60cm in well-prepared soil. Frequent shallow watering keeps roots near the surface and makes the plant drought-susceptible. Water deeply once or twice a week in dry weather rather than little and often. Hydrangeas are the thirstiest shrub in this group and will wilt visibly on a hot afternoon; camellias need summer water to hold next spring's buds.
Mulch in spring
A 7–10cm layer of well-rotted compost or horse manure applied around the base in March retains soil moisture, suppresses weeds, and feeds the soil biology as it breaks down. Keep mulch away from the stem base. For camellias, rhododendrons and azaleas use composted bark or leaf mould rather than manure, which is often alkaline.
Prune at bud break
Prune bush and shrub roses when the first buds break in late February — not in autumn. Autumn pruning removes the growth that protects the bud union through winter. Prune to outward-facing buds at a 45° angle just above the bud.
Know which wood flowers
The single most useful thing to know about a flowering shrub. If it flowers on last year's wood — mophead hydrangea, philadelphus, weigela, forsythia — prune straight after flowering and finish feeding early. If it flowers on this year's wood — hydrangea paniculata, buddleja, caryopteris — prune hard in March and feed through spring.
Expect some leaf marking
Foliar marking on roses and shrubs is close to universal in a UK summer and is rarely fatal to an established plant. Remove and dispose of affected leaves rather than composting them, keep the centre of the plant open so air moves through it, and choose varieties bred for resilience where you want a low-maintenance bed.
Stop feeding in mid-August
The single most common feeding mistake. Late feeding drives soft new growth that frost kills back to the wood, leaving open wounds. Feed stops mid-August. Let the last flushes flower and the plant harden naturally into autumn.
The Science Behind the Formula
The 5-3-5 ratio is not a generic template. It reflects the nutritional reality of how roses and flowering shrubs grow — producing both a substantial woody structure and flowers simultaneously across a season that runs from March to October in the UK.
Potassium and fragrance — the direct relationship
Floral fragrance in roses is produced by volatile terpenoid and benzenoid compounds synthesised in the petal tissue. The terpenoid pathway — which produces the monoterpene geraniol, the sesquiterpene germacrene D, and related rose scent compounds — is potassium-dependent: K activates the enzymes and ATP-producing proton pumps required for terpenoid biosynthesis. Plants with inadequate K or with K supplied from chloride sources produce measurably lower concentrations of these compounds.
Every gram of K in this formula comes from chloride-free sources — Sulphate of Potash and Yorkshire Polyhalite. Muriate of potash (potassium chloride), the dominant K source in most garden fertilisers, delivers Cl⁻ ions that compete with K⁺ at cellular transporters and suppress secondary metabolite synthesis. The fragrance gap between roses fed with chloride-free K formulas and those fed with standard fertilisers is not subtle to anyone who grows both.
Triacontanol and bud count
Triacontanol is a naturally occurring fatty alcohol present in Alfalfa Meal, first identified as a plant growth regulator in the 1970s by Ries and Houtz. Its mechanism involves activation of adenylate cyclase, raising intracellular cAMP levels and triggering cascades that increase the rate of meristematic cell division and secondary metabolite synthesis simultaneously. In rose-specific research, triacontanol application consistently increases the number of axillary buds that break and develop into flowering laterals — translating directly into more flowers per plant per flush. Professional rose growers have used alfalfa meal as a component of feeding programmes for decades; this formula incorporates it as a core ingredient.
Calcium and petal quality
Calcium is a structural component of pectin in cell walls. In rose petals, adequate Ca means walls with sufficient rigidity to maintain petal form throughout the life of the flower — in the garden and after cutting. Low Ca produces petals that lose form rapidly, bruise easily, and absciss prematurely. Gypsum provides immediately available Ca; Yorkshire Polyhalite provides sustained Ca across 50–60 days. The combination ensures Ca is continuously available across the full flowering season, not just immediately after application.
Nitrogen calibration
At 5% N, this formula is at the moderate end of the range for established roses. This is deliberate. Excess nitrogen in roses produces the conditions that create serious problems: the sappy, soft new growth that aphids colonise; the dense, poorly aerated canopy that creates the humid microclimate in which black spot and powdery mildew spread most rapidly; and the vigorous vegetative growth that produces canes and leaves at the expense of bud initiation. The organic nitrogen fractions in this formula mineralise progressively over 6–8 weeks — there is no nitrogen spike, no flush of sappy growth, and no sudden drop. The plant receives a consistent, moderate N supply that sustains growth without overwhelming it.
Systemic Acquired Resistance via chitin
Chitin — present in Mealworm Frass — is detected by pattern recognition receptors in plant cell membranes as a marker of fungal presence or insect feeding. Detection triggers a signalling cascade that activates Systemic Acquired Resistance pathways throughout the plant: salicylic acid accumulates, defence genes are upregulated, and the plant's capacity to mount rapid responses to subsequent pathogen attack is enhanced for weeks. For roses, which face consistent pressure from three major fungal pathogens, this priming effect is meaningfully useful — it does not prevent infection, but it significantly reduces the severity and spread of the diseases that inevitably arrive in a UK summer.
Hydrangea flower colour — what actually controls it
Sepal colour in Hydrangea macrophylla is produced by a single anthocyanin, delphinidin-3-glucoside. On its own that pigment is pink. It turns blue only when it forms a complex with an aluminium ion, stabilised by co-pigments in the sepal tissue. So the question is never what pigment the plant makes — it always makes the same one — but whether aluminium reaches the sepal in a form that can complex with it.
That comes down to two things, and neither of them is the NPK ratio on the bag. The first is soil pH: aluminium is soluble and root-available below roughly pH 5.5, and progressively locked up as pH rises. The second is phosphorus. Phosphate reacts with aluminium in the soil to form insoluble aluminium phosphate, removing it from solution — which is why a high-phosphorus feed is the most common reason a blueing programme quietly fails. At 3% P this formula sits at the modest end and will not work against an acidification programme, but we are not going to claim more than that: this is a fertiliser, and it does not change flower colour. If blue is the goal, the intervention is soil pH, applied with a sulphur-based acidifier and maintained over time. Pink and white hydrangeas, and the paniculata and arborescens types, are unaffected by any of this and simply want feeding.
References
- Ries, S. & Houtz, R. (1983) — Triacontanol as a plant growth regulator. HortScience, 18(5), 654–662
- Zörb, C. et al. (2014) — Potassium in agriculture: status and perspectives. Journal of Plant Physiology, 171(9), 656–669
- Bangerth, F. (1979) — Calcium-related physiological disorders of plants. Annual Review of Phytopathology, 17, 97–122
- Craigie, J.S. (2011) — Seaweed extract stimuli in plant science and agriculture. Journal of Applied Phycology, 23, 371–393
- Epstein, E. (1999) — Silicon. Annual Review of Plant Physiology and Plant Molecular Biology, 50, 641–664
- Fransen, K. et al. (2020) — Chitin-induced resistance in ornamental plants against Botrytis cinerea. Plant Pathology, 69(3), 520–531
- Higa, T. & Parr, J.F. (1994) — Beneficial and effective microorganisms for a sustainable agriculture and environment. International Nature Farming Research Center
- Johnston, A.E. & Dawson, C.J. (2018) — Polyhalite as a fertiliser for sustainable farming. Proceedings 826, International Fertiliser Society
- Lehmann, J. et al. (2011) — Biochar effects on soil biota. Soil Biology and Biochemistry, 43(9), 1812–1836
- Nardi, S. et al. (2009) — Physiological effects of humic substances on higher plants. Soil Biology and Biochemistry, 34(11), 1527–1536
Frequently Asked Questions
Begin in late March to early April when you see the first buds breaking — red buds on rose canes, swelling buds on hydrangeas and deciduous shrubs. This is the signal that the plant has moved out of dormancy and root activity has resumed. Applying before bud break is premature: the organic nitrogen fractions require active soil microbial activity to mineralise, and cold soil slows this significantly. Apply around the drip line of the plant, water in well, and repeat every 4–5 weeks through to mid-August for roses. Flowering shrubs need fewer applications and should finish earlier — see the How to Use tab.
Roses and flowering shrubs produce both a large vegetative structure (canes, stems, leaves) and flowers simultaneously across a long season — they are not fruiting plants. Equal N and K at 5% provides balanced support for stem strength, leaf health and bloom production. Phosphorus at 3% is intentionally modest — established woody plants do not need high P, and excess phosphorus can compete with micronutrient uptake in the slightly acidic soils roses and most flowering shrubs prefer. Around hydrangeas a low-phosphorus feed is the sensible choice for a further reason, covered below.
Every 4–5 weeks from late March to mid-August for most garden roses. Once-blooming roses (ramblers, many old garden roses) need only two applications — one in March and one after flowering. Repeat-flowering roses benefit from three to four applications spread through the season. Flowering shrubs need less: two to three applications is normal, and mophead and lacecap hydrangeas should be finished by the end of June. Stop by mid-August for most rose varieties — late feeding encourages soft cane growth that is killed by autumn frosts.
Yes — the 5-3-5 formula works for hybrid teas, floribundas, shrub roses (including English roses), climbing roses, ramblers, miniature roses and ground cover roses, and equally for hydrangeas, camellias, rhododendrons, azaleas, philadelphus, weigela, buddleja, lilac, viburnum and the general run of flowering shrubs. Because calcium comes from pH-neutral gypsum rather than lime, it is safe on the acid-loving shrubs as well. Feeding rates and timing vary by type — see the How to Use tab for the full table.
Yes — directly. Floral fragrance compounds in roses are potassium-dependent secondary metabolites. This formula uses exclusively chloride-free potassium (Sulphate of Potash and Yorkshire Polyhalite) — muriate of potash, the K source in cheaper fertilisers, suppresses these scent pathways. Alfalfa Meal adds triacontanol, which increases secondary metabolite production including fragrance compounds. The combination consistently produces stronger, more complex scent compared to plants given standard balanced feeds.
Yes. For potted roses and shrubs, use 3–4g per litre of compost as an initial charge when potting, then top-dress at 2g per litre every 4 weeks. Always water very thoroughly after applying. The fermented biochar component helps retain potassium and other nutrients between waterings — particularly valuable for container roses and potted hydrangeas in free-draining terracotta pots that can dry quickly in summer.
Stop by mid-August for most garden roses. Late feeding encourages soft new cane growth that does not have time to lignify before the first frosts — this new growth is then killed back, leaving open wounds that can introduce disease. The exception is climbing roses on warm south-facing walls, which can be fed until early September as the wall warmth extends the hardening-off period. Flowering shrubs should stop earlier: mophead and lacecap hydrangeas after their June feed, most other shrubs by late July, so the wood has the rest of the summer to ripen.
Roses prefer slightly acidic to neutral soil, pH 6.0–7.0, with the ideal around 6.5. Below pH 6.0, manganese and aluminium can reach toxic levels; above pH 7.5, iron and manganese become locked up and yellow leaves appear. The humic and fulvic acid in this formula helps buffer micronutrient availability across a wider range, but soils significantly outside 6.0–7.0 should be adjusted with lime (too acidic) or sulphur (too alkaline). Camellias, rhododendrons, azaleas and hydrangeas want it lower, around 5.0–6.0. This blend is pH-neutral, so it will not push soil pH up underneath them, but it is a feed rather than an acidifier — for that use our Sulphur Soil Acidifier.
It is compatible with seaweed teas and low-nutrient biostimulant liquids. If using a liquid rose or shrub feed as well, reduce the dry powder application to half rate or skip that cycle — combining two full-rate programmes pushes nitrogen above what the plant can use efficiently, resulting in soft, disease-prone growth. The dry powder is the better baseline for sustained nutrition through the season; liquid feeds work best as a boost just before the main June flush.
Yes. Feeding hydrangeas is one of the main uses this blend is built for. The 5-3-5 ratio gives them the nitrogen for leaf and stem and the chloride-free potassium that supports flower substance, and the phosphorus is deliberately low — which matters more for hydrangeas than for most plants. Feed mophead and lacecap types at bud break in late March and again in June, then stop, so the wood ripens before autumn and next year's buds survive the winter. Hydrangea paniculata and arborescens flower on the current season's growth and can take their second feed in late May instead. Rates are in the How to Use tab.
No, and we would rather say so plainly than sell you something on a hope. Blue hydrangea colour is not produced by a fertiliser. It happens when the soil is acidic — around pH 5.5 and below — and aluminium is present in a form the roots can take up and carry to the sepal, where it complexes with the plant's own pigment. Phosphorus is the classic antagonist here: it binds aluminium into insoluble compounds and takes it out of circulation, which is why high-phosphorus feeds are the usual reason a blueing programme fails. At 3% P this blend is modest and will not obstruct you, but the limiting factor for blue flowers is your soil pH, not your feed. If that is your goal, lower the pH with our Sulphur Soil Acidifier and see the hydrangea and ericaceous range. White varieties will not change colour whatever you do.
Yes. The calcium in this formula comes from gypsum, which is pH-neutral — unlike lime, it supplies calcium without raising soil pH, so it will not work against an acid soil the way a limed general fertiliser can. Feed at bud break and again immediately after flowering, which is when next year's buds are being set. Scatter it on the surface rather than forking it in: the roots of all three sit in the top few centimetres and are easily damaged. If the leaves are yellowing between the veins on an otherwise well-fed plant, the problem is soil pH locking up iron rather than a shortage of nutrients, and the fix is an acidifier.
The useful question is which wood the shrub flowers on. Shrubs that flower on last year's wood — mophead hydrangea, philadelphus, weigela, forsythia, deutzia — should be fed at bud break and again straight after flowering, then left alone so the new growth ripens. Shrubs that flower on this year's wood — hydrangea paniculata, buddleja, caryopteris, hardy fuchsia — are cut back hard in March and fed through spring and early summer, since they have a whole season's growth to build. Either way, flowering shrubs need fewer applications than a repeat-flowering rose and should finish earlier in the summer.
Usually not. On mophead and lacecap hydrangeas the most common cause is that the flower buds were lost — either pruned off in spring, or frosted, because these types carry next year's buds on the wood they made last summer. Cutting them back in autumn or early spring removes the flowers before they open. The second most common cause is too much shade. A high-nitrogen feed applied late in the season can contribute by pushing soft growth that never ripens, which is one reason this blend is moderate at 5% N and why we suggest stopping hydrangea feeding after June. If you want a hydrangea that tolerates hard spring pruning, grow a paniculata or arborescens type instead.
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