Fertiliser
Tomato Feed 3-4-6 | Slow-Release, Made with Organic Ingredients
A slow-release 3-4-6 feed for tomatoes.
from £11.50
Customer highlight
Arrived quickly and exactly as described. This is an expensive product for what it does, however, I'm hopeful this will give my organic strawberries a boost in flavour, yield and growth.
Editorial highlight from marketplace and store reviews — separate from the full review list below.
Made by Growers · Backed by Science
Strawberry fertiliser 3-2-7: a high-potash strawberry feed with 19 ingredients
3-2-7 NPK 19 Ingredients High Potash for Flavour Slow Release Full Ingredient Transparency Handcrafted in Stockport
Dr Forest strawberry fertiliser is a slow-release, high-potash strawberry feed with an NPK of 3-2-7, blended from 19 organic and mineral ingredients. Potassium runs at more than twice the nitrogen because a strawberry plant short of potassium gives poorly coloured, pulpy fruit, while too much nitrogen gives you leaf and lowers the sugars. It is mixed by hand in small batches in Stockport and carries 7.2% calcium and 2.5% magnesium alongside the NPK. Every ingredient is named on the next tab.
It is a fertiliser for strawberry plants wherever they grow, from hanging baskets and planters to allotment rows, scattered every 4–6 weeks rather than poured weekly from a watering can. Seaweed, biochar, humic acids and EM-1 microbes look after the soil around the shallow roots.
3-2-7NPK ratio
19Ingredients
7.2%Calcium, four main sources
4–6 wkBetween feeds
What this strawberry plant food does
- Potassium first — 7% potash against 3% nitrogen, mostly from two low-chloride sources.
- Nitrogen kept moderate — enough for crowns and leaves, released slowly by soil microbes.
- Calcium from four main sources — gypsum, polyhalite, phosphorous plant meal and rock phosphate.
- Magnesium for the leaves — 2.5%, mainly from Epsom salt and polyhalite.
- Slow release — plant meals and rock phosphate break down over weeks, so there is no weekly dosing.
- Soil life included — EM-1 microbes, fermented biochar, humic and fulvic acids and two kinds of seaweed.
Dr Forest strawberry fertiliser vs a weekly liquid feed
Dr Forest Strawberry Fertiliser 3-2-7 — slow-release granular feed
- 19 ingredients, each named, with the reason it is there
- NPK 3-2-7 plus 7.2% calcium and 2.5% magnesium stated
- Low-chloride potash from polyhalite and sulphate of potash
- Scattered every 4–6 weeks, scratched in and watered
Typical liquid strawberry or tomato feed — soluble concentrate
- Diluted into the can every week or so from flowering
- Label usually gives the NPK and a handful of trace elements
- Nutrients arrive in pulses: a strong dose, then little until the next can
- Feeds the plant and does little for the soil
Handcrafted in Stockport
Every batch is blended by hand at our workshop in Stockport, Greater Manchester, and packed in compostable kraft bags. Dr Forest is named after Joe's grandfather, Dr Forrest, a GP in a Lancashire mining town near Preston who kept a back-garden plot for the runner beans he turned into piccalilli for family and friends. The potash backbone of this feed is Yorkshire polyhalite; here is why we use it. Made by Growers. Backed by Science.
What's Inside
All 19 ingredients in our strawberry fertiliser, and why each one is there
A multi-input blend, with every ingredient listed. Yorkshire polyhalite is the largest at 21% of the blend, and alfalfa meal, at 10%, is one of the largest. The label on each card is the job that ingredient does.
01K · Ca · Mg · S
Yorkshire polyhalite — North Yorkshire, mined mineral
21% of the blend. One low-chloride mineral carrying 14% K₂O, 17% CaO, 6% MgO and 48% SO₃, mined 1,200m below the North Sea. We also sell polyhalite on its own.
02Nitrogen
Nitrogen plant extract — plant-derived, steady release
The main nitrogen carrier, a plant protein concentrate at 12% nitrogen, released by soil microbes over several weeks.
03N · Triacontanol
Alfalfa meal — slow release
10% of the blend. Around 2.5% nitrogen, trace minerals and triacontanol, a leaf-wax compound that raised fruit sugars when sprayed on strawberries (Pang et al., 2020). More on alfalfa meal as a fertiliser.
04Calcium · Sulphur
Gypsum (calcium sulphate) — mineral, fast
23% calcium and 18.6% sulphur as sulphate, available once watered in. Gypsum adds calcium without raising soil pH.
05Potassium
Sulphate of potash — mineral, fast
50% K₂O and low in chloride: the quick potassium in the mix. Strawberry is one of the most salt-sensitive crops (Sun et al., 2015), so there is no muriate of potash (potassium chloride) in this blend.
06Magnesium
Epsom salt (magnesium sulphate) — mineral, fast
The fastest magnesium source in the blend. Magnesium sits at the centre of every chlorophyll molecule; polyhalite adds a second supply.
07Phosphorus · Calcium
Phosphorous plant meal — plant-derived, fast to moderate
A calcined plant meal with around 15% P₂O₅ and 9% CaO, released within weeks for rooting and flower formation.
08Trace elements
Scottish seaweed meal — hand-harvested
Trace elements plus the compounds that make seaweed a biostimulant: small amounts of plant hormones, betaines and seaweed polysaccharides (Ali et al., 2021).
09Soil carbon
Fermented biochar — British
2% of the blend. Porous, stable carbon that gives microbes somewhere to live; across 61 studies, biochar raised soil microbial biomass by 26.5% (Kerner et al., 2023).
10Slow P reserve
Micronised rock phosphate — mineral, slow
31% P₂O₅ with a high calcium share. It dissolves slowly, so it is still working when everbearers are setting fruit in August and September.
11Chelation
Humic and fulvic acids — biostimulant
Humic substances that hold micronutrients in forms roots can take up (Ampong et al., 2022). Fulvic acid is the smaller, more soluble fraction.
12Nitrogen
Rapeseed meal — British, slow release
Another slow nitrogen source, and food for the soil microbes that break it down.
13N · Chitin
Mealworm frass — sustainably reared
Droppings, shed skins and feed residue from mealworm rearing. In a pot trial it matched mineral NPK for plant growth and raised soil microbial activity (Houben et al., 2020).
14Nutrient holding
Clay minerals — montmorillonite and illite
Clays that hold potassium, calcium and magnesium and release them between waterings; useful in light soils and pots.
15Biostimulant
Seaweed extract — soluble fraction
The soluble part of seaweed, quicker-acting than the meal. Strawberry plants given seaweed extract have produced fruit with more sucrose and fructose (Ali et al., 2021).
16Trace minerals
Volcanic rock dust (basalt) — mineral, slow
Ground basalt that releases iron, manganese, zinc, copper and silicon as it weathers; see the rock dust guide.
17Microbes
EM-1 microorganisms — living culture
Lactic acid bacteria, yeasts and other beneficial microbes that get the meals and minerals breaking down. We also sell EM-1 on its own.
18Silicon
Silica meal — mineral, structural
Silicon is taken up as silicic acid and laid down as silica in cell walls. It is not an essential nutrient, but it helps plants under drought and salt stress (Luyckx et al., 2017).
19Botanicals
Herbal mixture — comfrey, nettle, yarrow and chamomile
Comfrey leaf is rich in potassium; the others add plant material for soil life. The evidence for individual herbs is thin, so it is a supporting act.
How to Use
How to use strawberry fertiliser: rates, timing and method
Strawberries are shallow-rooted
Apply to the soil surface and incorporate lightly into the top 5–10cm only. Deep incorporation is unnecessary and can damage the shallow fibrous root system. Always leave a 10cm gap from the crown to prevent burn. Water thoroughly after every application.
Step-by-step: pots, planters and hanging baskets
- Charge the compost. Mix 5–10g per litre through the full volume before planting (5g/L with mycorrhizal inoculant, 10g/L without).
- Plant and water. Plant into the charged compost and water thoroughly.
- Top-dress once established. From 4–6 weeks after planting, or early spring on older plants: 1–3g per litre of pot volume every 4–6 weeks.
- Scratch in and water. Apply to the compost surface, scratch in lightly, water thoroughly.
Application rate table
Soil preparation — before planting
| Situation | Rate | Method | Notes |
|---|---|---|---|
| Beds and raised beds | 100–170g per m² | Work into top 10–15cm before planting | 100g/m² in fertile soil or for light-feeding alpine types. 130g/m² for average garden soil. 170g/m² for maximum flavour in new beds, or when pushing sweetness and aroma to the peak; this rate gives a strong potassium foundation for the season. |
| Single plants at planting | 15–40g per plant (1–3 tablespoons) | Mix into soil around each crown | Leave a 10cm gap from the crown. 15g for small transplants or alpine types. 25–30g for established crowns. 40g for maximum flavour; this concentrates potassium in the root zone. |
| Containers, pots and hanging baskets | 5–10g per litre of compost | Mix through full volume before planting | 5g/L if using mycorrhizal fungi inoculant (lower P avoids suppressing colonisation). 10g/L in plain compost without mycorrhizal fungi. |
Feeding — ongoing through the season
| Situation | Rate | Frequency | Notes |
|---|---|---|---|
| Rows and beds — top-dressing | 80–160g per metre of row | Every 4–6 weeks | 80g/m for maintenance and light-feeding varieties. 120g/m for standard feeding. 160g/m during peak fruiting for maximum sweetness and aroma. Spread evenly along the row, lightly scratch in and water well. Avoid direct contact with crowns. |
| Single plants — top-dressing | 15–40g per plant (1–3 tablespoons) | Every 4–6 weeks | 15g for light feeders. 25–30g for standard feeding. 40g during peak fruiting for maximum flavour. Apply in a ring 10–15cm from the crown, incorporate lightly and water in. |
| Containers and pots — top-dressing | 1–3g per litre of pot volume | Every 4–6 weeks | 1g/L for light feeders and alpine types. 2g/L for standard feeding. 3g/L during peak fruiting for maximum sweetness and aroma; this is the rate that pushes potassium delivery highest. Apply to the compost surface, scratch in lightly and water thoroughly. |
When to start feeding
Early spring as growth resumes, or 4–6 weeks after planting once established. Apply every 4–6 weeks during the growing season. Focus on the pre-flowering and fruiting stages for maximum sweetness. Reduce or stop after the main harvest to avoid excess foliage.
On fruit trees and soft fruit
Strawberries want a steady supply of potash for sweet, well-coloured berries, and only a modest amount of nitrogen. Too much nitrogen gives big leafy plants, soft fruit and more grey mould. Feed at the key moments rather than all season.
Summer-fruiting (June-bearing) strawberries in the ground
- Main feed, straight after picking, when you tidy the old leaves: 100 g per m² (about 25 g per plant), scattered around the plants and watered in. This feeds next year's flower buds, which form in late summer and autumn.
- Spring: only if plants are weak or on light, sandy soil, give 50 g per m² in March. Spring feeding mostly makes leaves.
Everbearing (perpetual) strawberries in the ground
- 75 g per m² in April, then 50 g per m² in early June and 50 g per m² in mid-July.
Don't go above 200 g per m² in a season, and don't feed after mid-August.
New beds: fork 100–130 g per m² into the soil before planting. Only go up to 170 g per m² if a soil test shows low potash. Summer-fruiting plants then need nothing more until after their first picking.
Pots, troughs and grow bags
- Mix 5 g per litre into the compost at planting. Most multipurpose composts already contain some fertiliser, so only go up to 10 g per litre in an unfertilised mix.
- Summer-fruiting: top-dress 2 g per litre of compost after cropping.
- Everbearers: top-dress 1–2 g per litre every 4–6 weeks while cropping.
- Water in after feeding.
Good to know
- Keep granules off leaves and crowns.
- Raspberries, currants and gooseberries: 80–100 g per m² in March works well. Don't feed summer raspberries after the end of July.
- Figs: feed lightly. A fig in the ground with its roots restricted (in a lined planting pit) can have one dressing of 40–50 g in March–April. One growing unrestricted in mulched soil needs nothing unless growth is weak (less than about 30 cm of new shoot a year). Figs in pots: 2 g per litre of compost in April and again in late May. Give a fig only one spring feed, this or another fruit feed, and stop by midsummer.
Seasonal feeding guide
| When | Feeding |
|---|---|
| Feb–Mar | First feed as new growth appears (100–170g/m² or 15–40g per plant). |
| May | Second feed for June-bearers (80–160g/m of row). |
| June | Feed everbearing and day-neutral varieties every 4 weeks at the lower end. |
| July | Post-harvest feed for June-bearers — critical for next year. |
| August | Final feed for everbearing varieties. Stop feeding June-bearers by late August. |
| Nov–Jan | Plants dormant. No feeding. |
Feeding by variety type
| Type | Rate | Frequency | Key timing |
|---|---|---|---|
| June-bearing | Standard range | Every 4–6 weeks | Pre-flowering and immediately post-harvest; stop by late August |
| Everbearing | Lower end of range | Every 4 weeks | Continuous through season |
| Day-neutral | Lower end of range | Every 4 weeks | Continuous, lighter feeds |
| Alpine | Lowest range | Every 6–8 weeks | Spring and midsummer only |
Containers, hanging baskets and strawberry planters: charge the compost at 5–10g per litre before planting, then feed every 4 weeks at the lower end of the range. After the harvest: for June-bearers, one application immediately after harvest, then stop by late August; for everbearing types, continue feeding through to the final flush, then stop. With mycorrhizal fungi: use the lower compost rate (5g/L) initially to avoid high phosphorus inhibiting colonisation, apply the inoculant directly to the roots at planting, and resume normal rates after 4–6 weeks once the networks have established. The top-dressing guide covers the scratch-in method.
Adjusting soil pH before planting
Strawberries prefer slightly acidic soil at pH 5.5–6.5, ideally around 6.2. Test annually, and incorporate any correction 3–12 months before planting.
| To | Material and rate | Time to take effect |
|---|---|---|
| Lower pH | Elemental sulphur at 100–200g/m² | 3–6 months |
| Raise pH | Agricultural lime at 100–300g/m² | 3–12 months |
The calcium from gypsum in this formula does not raise pH. More detail in how to make soil more acidic, or raise the pH.
Measuring tip
3 level teaspoons = 1 tablespoon ≈ 15g. We recommend mixing the fertiliser with an equal volume of compost before application: it cuts down dust and coats the granules in microbe-rich compost.
Works well combined with…
Use Dr Forest Seaweed Powder as a fortnightly foliar spray for a seaweed biostimulant without extra nitrogen. Apply Dr Forest Liquid Gypsum as a root drench every 2–4 weeks for additional calcium. Apply mycorrhizal fungi inoculant at planting for improved nutrient uptake.
Storage
Cool, dry place out of direct sunlight. Keep sealed between uses. Effective for at least 18 months.
Growing Guide
Strawberry growing guide: June-bearers, everbearers and a UK feeding year
Strawberries are easy to grow in a British garden and easy to grow badly. The difference is mostly type, site, watering and the age of the plants.
June-bearers vs everbearers
June-bearers (summer-fruiting)
- One main crop over 2–4 weeks in June and July
- Set next year's flower buds as days shorten in autumn (Hytönen & Kurokura, 2020)
- Honeoye and Christine early; Elsanta, Cambridge Favourite, Hapil and Sonata mid-season; Florence and Symphony late
- Plant runners in late summer or early autumn for a full crop next June
Everbearers (perpetual)
- Smaller flushes from June through to October
- Flower under long days, so they keep going all summer
- Flamenco, Buddy, Finesse and Aromel are widely sold in the UK
- A steady trickle of fruit that suits pots and baskets
Day-neutral and alpine types
Day-neutral is the American name for everbearing types that flower regardless of day length, such as Albion and San Andreas. Alpines are a separate species with small, aromatic berries and few or no runners.
Feeding adjustments by variety type
June-bearing — Elsanta, Cambridge Favourite, Honeoye, Hapil, Florence, Sonata
One concentrated flush over 2–4 weeks in June–July. Feed in early spring as growth resumes, again just before flowering, and once more immediately after harvest to build reserves for next year's crowns. Stop feeding by late August. The post-harvest feed is as important as the pre-flowering one: it carries the plant into autumn, when next year's flower buds form.
Everbearing — Flamenco, Buddy, Finesse, Malling Allure
Multiple flushes from June through to October. Lighter, more frequent feeding keeps potassium supply steady without nitrogen spikes between flushes.
Day-neutral — Albion, Seascape, San Andreas, Sweet Ann
These fruit continuously regardless of day length. Manage them like everbearers but with even lighter individual applications. Watch for lush foliage and adjust downward; they are sensitive to excess nitrogen.
Alpine — Alexandria, Mignonette, Baron Solemacher, Mara des Bois
Small, intensely flavoured berries on plants that need minimal feeding. Overfeed and you lose the intensity. Mara des Bois is technically a day-neutral but grows like an alpine, so feed it as an alpine.
Pots, planters and baskets vs beds and allotment rows
Containers, hanging baskets and strawberry planters
- Fruit hangs clean; pots can go under cover for an early crop
- Nutrients wash out fast; the biochar and clay minerals help hold them
- Water daily in warm weather, twice in a heatwave
- Feed every 4 weeks at the lower end of the range; replace the compost yearly
Beds, raised beds and allotments
- More soil buffers water and nutrients
- Space plants 35–40cm apart, in rows about 75cm apart (RHS, n.d.)
- Tuck straw under forming fruit to keep it clean and dry
- Water deeply 2–3 times a week in dry spells
Watering: steady, and aimed at the soil
Swelling berries are mostly water. Keep the soil evenly moist from flowering to the last pick, and water the soil rather than the plant; berries that sit wet in still air are the ones that rot.
01
Pots, baskets and planters
Check daily from flowering; water until it runs from the base. If dry compost sheds water, see why pots and baskets stop taking water.
02
Beds and allotment rows
A deep morning soak two or three times a week in dry weather; a seep hose under the straw keeps the fruit dry.
03
Greenhouse and polytunnel
Plants dry out faster and fruit earlier; start daily checks sooner, and open doors on warm days for air and bees.
Calcium moves with water
Calcium reaches the fruit in the water flowing through the plant, mostly around fruit set (Hocking et al., 2016), so a dry spell at flowering costs the berries calcium whatever the soil holds.
Runners, renovation and replacing plants
- Pinch out runners on fruiting plants. Runners and flowers compete for the same buds (Hytönen & Kurokura, 2020).
- Renovate June-bearers after the last pick. Cut off the old leaves about 10cm above the crown (RHS, n.d.) and clear old straw.
- Give the post-harvest feed. One application immediately after harvest, watered in; stop feeding June-bearers by late August.
- Root new plants if you want them. Allow 3–4 runners per mother plant after harvest, peg into small pots of compost, sever once rooted (4–6 weeks) and plant out in autumn.
- Replace plants every 3–4 years. Cropping quality declines after the third season; start the new bed on fresh ground.
UK seasonal timeline
| Month | Task | Feeding |
|---|---|---|
| Feb–Mar | Clear dead leaves. Move pots under cover for an early crop. | First feed as new growth appears (100–170g/m² or 15–40g per plant) |
| April | Flowering begins. Fleece on frosty nights. Remove runners. | — |
| May | Fruit sets. Tuck straw under developing fruit. | Second feed for June-bearers (80–160g/m of row) |
| June | Main harvest for June-bearers; pick every day or two. | Feed everbearing and day-neutral varieties every 4 weeks at the lower end |
| July | Renovate June-bearers. Let chosen runners root. | Post-harvest feed for June-bearers — critical for next year |
| August | Sever rooted runners; pot up or plant out. | Final feed for everbearing varieties. Stop feeding June-bearers by late August |
| Sep–Oct | Plant new runners into a prepared bed. | — |
| Nov–Jan | Plants dormant. Protect containers from hard frost. | No feeding |
Common problems
Small, bland or sour berries
Full sun counts most; water evenly and replace old plants. Flavour also dips late in a picking season, when falling sugars take aroma with them (Schwieterman et al., 2014).
Plenty of leaves, few flowers
Stop any high-nitrogen feeding and remove runners. New plants make leaf first; give them a season.
Flowers with a black centre
Frost blackens the centre of the flower, the part that becomes the berry, while the petals look fine; those flowers will not fruit. Fleece on frosty nights in April and May.
Knobbly or misshapen berries
Flesh only swells evenly under pollinated seeds. Under cover, let bees in or brush the flowers.
Leaves reddening or yellowing between the veins
Most common on light, sandy soils and in pots; this feed carries magnesium from Epsom salt and polyhalite. Old leaves also colour naturally in autumn.
The Science
The science of strawberry flavour, and where feeding fits
A strawberry's flavour comes down to sugars, acids and aroma. When 166 consumers rated fruit from 35 varieties and breeding lines, sweetness and strawberry flavour intensity drove how much they liked it: total sugars explained nearly half the variation, and sourness made no measurable difference (Schwieterman et al., 2014).
Why a 3-2-7 ratio for strawberries
Potassium is sometimes called the quality element: it runs enzymes in photosynthesis and regulates the stomata, and without enough of it the plant makes and uses less sugar (Hasanuzzaman et al., 2018). Strawberry plants short of it give shrivelled, poorly coloured, pulpy fruit (Taghavi et al., 2019). Nitrogen cuts both ways: more yield, but lower sugars in one of two varieties in a Florida trial (Agehara, 2021). Hence more than twice as much potassium as nitrogen, with the nitrogen in slow organic forms.
3-2-7NPK ratio
7.2%Calcium
0.5%Leaf chloride linked to scorch
+26.5%Soil microbial biomass with biochar
Variety sets the ceiling for flavour; feeding, light and water decide how close each plant gets to it.
What makes a strawberry taste of strawberry
| Compound | Type | What the study found |
|---|---|---|
| Sucrose | Sugar | The single biggest contributor to overall liking |
| Hexyl acetate, hexyl butanoate | Esters (fruity aroma) | Raised perceived sweetness independently of sugar |
| γ-Dodecalactone | Lactone | Raised perceived sweetness independently of sugar |
| 1-Penten-3-one | Ketone | Raised perceived sweetness independently of sugar |
| Acidity (perceived sourness) | Taste | No link with overall liking |
All rows: Schwieterman et al. (2014), 81 volatiles measured.
What each part of the formula does
01
Potassium, mainly from two low-chloride sources
Sulphate of potash is the fast source. Yorkshire polyhalite adds calcium, magnesium and sulphur with its potassium, and in four UK field trials it matched or beat muriate and sulphate of potash for potassium uptake in three (Lillywhite et al., 2020).
02
Nitrogen: enough, and no more
In a two-season Florida trial, extra early nitrogen kept adding yield in 'Florida Radiance' while its early-season soluble solids fell by 0.91 °Brix for every extra kilogram per hectare per day; in 'Florida127' yield peaked at an intermediate rate (Agehara, 2021). Three per cent nitrogen, released slowly, aims for the useful side of that trade.
03
Calcium goes in early, with the water
Calcium barely moves in the phloem, so fruit gets it from the water stream, and most of it arrives early in fruit development, when the young fruit transpires fastest. It cross-links pectin in cell walls (Hocking et al., 2016); in strawberry trials, calcium sprays gave firmer fruit (Taghavi et al., 2019).
04
Low chloride for a salt-sensitive crop
Strawberry is one of the most salt-sensitive crops, and leaf chloride above 0.5% is linked to leaf scorch and lost yield (Sun et al., 2015). Muriate of potash is potassium chloride; the two main potash sources in this blend are sulphates.
05
Soil biology does part of the feeding
Organic strawberry fields on 13 paired Californian farms held more carbon, nitrogen and microbial biomass than conventional ones (Reganold et al., 2010). Biochar raised microbial biomass by 26.5% across 61 studies (Kerner et al., 2023), and mealworm frass lifted microbial activity most alongside mineral fertiliser (Houben et al., 2020). The evidence for humic acids is mostly from laboratory and pot work, and results are inconsistent (Ampong et al., 2022).
06
The small print: triacontanol, seaweed and silicon
Triacontanol sprayed on strawberries raised sugars and anthocyanins (Pang et al., 2020), as seaweed extract has raised fruit sugars (Ali et al., 2021); a granular feed delivers far less of either, so read that as mechanism, not promise. Silicon is laid down in cell walls, strengthens stems and helps plants under drought and salt stress (Luyckx et al., 2017).
Study data
| Study | Scope | Finding |
|---|---|---|
| Reganold et al. (2010) | 13 paired organic and conventional strawberry fields, California | Organic fruit: more antioxidants, vitamin C and dry matter, longer shelf life, but 13.4% smaller. |
| Schwieterman et al. (2014) | 54 samples, 35 varieties and breeding lines, 166 consumers | Sugars explained nearly half of liking; some aroma compounds raised sweetness without extra sugar. |
| Agehara (2021) | Florida field trial, two seasons, two varieties | More early nitrogen raised total-season yields by up to 56–58%; soluble solids fell in one variety. |
| Sun et al. (2015) | Seven varieties under salt stress for four months, greenhouse | Salt cut growth and fruit yield, by up to 56% in two varieties at the highest level; 'Albion', 'Camarosa' and 'San Andreas' coped best. |
Scientific references
- Agehara, S. (2021). Characterizing early-season nitrogen fertilization rate effects on growth, yield, and quality of strawberry. Agronomy, 11(5), 905.
- Ali, O., Ramsubhag, A. & Jayaraman, J. (2021). Biostimulant properties of seaweed extracts in plants: implications towards sustainable crop production. Plants, 10(3), 531.
- Ampong, K., Thilakaranthna, M.S. & Gorim, L.Y. (2022). Understanding the role of humic acids on crop performance and soil health. Frontiers in Agronomy, 4, 848621.
- Hasanuzzaman, M., Bhuyan, M.H.M.B., Nahar, K., et al. (2018). Potassium: a vital regulator of plant responses and tolerance to abiotic stresses. Agronomy, 8(3), 31.
- Hocking, B., Tyerman, S.D., Burton, R.A., et al. (2016). Fruit calcium: transport and physiology. Frontiers in Plant Science, 7, 569.
- Houben, D., Daoulas, G., Faucon, M.-P., et al. (2020). Potential use of mealworm frass as a fertilizer: impact on crop growth and soil properties. Scientific Reports, 10, 4659.
- Hytönen, T. & Kurokura, T. (2020). Control of flowering and runnering in strawberry. The Horticulture Journal, 89(2), 96–107.
- Kerner, P., Struhs, E., Mirkouei, A., et al. (2023). Microbial responses to biochar soil amendment and influential factors: a three-level meta-analysis. Environmental Science & Technology, 57(48), 19838–19848.
- Lillywhite, R., Wiltshire, J.J.J., Webb, J., et al. (2020). The response of winter barley (Hordeum vulgare) and forage maize (Zea mays) crops to polyhalite, a multi-nutrient fertilizer. The Journal of Agricultural Science, 158(4), 269–278.
- Luyckx, M., Hausman, J.-F., Lutts, S., et al. (2017). Silicon and plants: current knowledge and technological perspectives. Frontiers in Plant Science, 8, 411.
- Pang, Q., Chen, X., Lv, J., et al. (2020). Triacontanol promotes the fruit development and retards fruit senescence in strawberry: a transcriptome analysis. Plants, 9(4), 488.
- Reganold, J.P., Andrews, P.K., Reeve, J.R., et al. (2010). Fruit and soil quality of organic and conventional strawberry agroecosystems. PLoS ONE, 5(9), e12346.
- RHS (Royal Horticultural Society) Advice Team (n.d.). How to grow strawberries. RHS Gardening, rhs.org.uk, accessed September 2026.
- Schwieterman, M.L., Colquhoun, T.A., Jaworski, E.A., et al. (2014). Strawberry flavor: diverse chemical compositions, a seasonal influence, and effects on sensory perception. PLoS ONE, 9(2), e88446.
- Sun, Y., Niu, G., Wallace, R., et al. (2015). Relative salt tolerance of seven strawberry cultivars. Horticulturae, 1(1), 27–43.
- Taghavi, T., Siddiqui, R. & Rutto, L.K. (2019). The effect of preharvest factors on fruit and nutritional quality in strawberry. In T. Asao & M. Asaduzzaman (Eds.), Strawberry: Pre- and Post-Harvest Management Techniques for Higher Fruit Quality. IntechOpen.
Figures describe the published literature on these ingredient classes and are not product-specific yield guarantees.
Questions & Answers
Strawberry feed questions, answered
One high in potash and moderate in nitrogen, with calcium and magnesium: this one is 3-2-7 with 7.2% calcium and 2.5% magnesium, applied every 4–6 weeks. High-nitrogen feeds push leaf rather than fruit. Polyhalite vs sulphate of potash explains the two potash sources.
Yes, for a good crop more than one year running: they fruit heavily from shallow roots, and pots run short quickly. Start in early spring as growth resumes, or 4–6 weeks after planting once established.
A high-potash feed, every 4–6 weeks during the growing season. Everbearing and day-neutral varieties, and plants in containers, get a feed every 4 weeks at the lower end of the range; alpines every 6–8 weeks, spring and midsummer only. June-bearers are fed as growth resumes, just before flowering and immediately after harvest, and not after late August.
At a push, since both crops want more potassium than nitrogen when fruiting. But strawberries are salt-sensitive, and a liquid tomato feed is a weekly dose of soluble salts; this blend gives low-chloride potash, calcium and magnesium in one granular feed. For the tomatoes themselves, see our organic tomato fertiliser.
Yes. Everbearing and day-neutral types need lighter, more frequent feeds (every 4 weeks at the lower rate) to keep potassium steady across the extended season. June-bearers need stronger feeds at key moments: pre-flowering, and immediately post-harvest to build next year's flower buds.
For June-bearers, yes: the post-harvest feed is critical, because it carries the plant into autumn, when next year's flower buds form. One application immediately after harvest, then stop by late August. For everbearing types, continue feeding through to the final flush, then stop.
Yes. Charge the compost at 5–10g per litre before planting, then top-dress every 4 weeks at the lower end of the range. The biochar and clay minerals help hold nutrients that frequent watering washes through a basket.
Nitrogen raises yield but can lower the sugars: in a Florida field trial, each step up in early-season nitrogen lowered soluble solids in one of the two varieties tested. The 3% nitrogen is enough for healthy crowns; potassium does the heavy lifting once the plant is fruiting.
It helps, within limits. Calcium cross-links the pectin in cell walls, but it reaches the fruit in the plant's water, mostly around fruit set, so steady watering at flowering matters as much as the calcium in the feed. No feed will firm up a soft variety in a wet week.
Yes. Use the lower compost rate (5g/L) initially to avoid high phosphorus inhibiting colonisation, apply the inoculant directly to the roots at planting, and resume normal rates after 4–6 weeks once the networks have established. More in our guide to mycorrhizal fungi.
pH 5.5–6.5, ideally around 6.2. Test annually. The gypsum in this formula supplies calcium without raising pH, unlike lime, which would push pH above the ideal range. Rates for correcting pH are on the How to Use tab.
Yes, used as directed: organic and mineral ingredients, no synthetic chemicals or long-lasting toxins, and no withholding period before picking. Keep the bag sealed and out of reach, though; dogs are drawn to organic meals, and a bellyful of any fertiliser upsets a stomach.
It is made with plant meals, natural minerals and a live microbial culture, with no synthetic chemicals and no GMO inputs. The blend does not carry an organic certification logo, so we do not claim one.
In winter, and late in the season. From November to January the plants are dormant, so don't feed them at all. Stop feeding June-bearers by late August, after their post-harvest feed in July. Give everbearing varieties their last feed in August. Feeding late pushes soft leaf when the plant should be firming up for winter and setting next year's flower buds.
Not ideal. Strawberries fruit best on more potash than nitrogen, and extra nitrogen tends to give you leaf and softer, less sweet berries. Strawberries are also salt-sensitive, which concentrated soluble feeds don't suit. This feed is 3-2-7, with 7.2% calcium and 2.5% magnesium, and releases slowly over 4–6 weeks.
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