Bloom 2-8-4 — a high-phosphorus organic feed for flower and fruit
Bloom 2-8-4 is a high-phosphorus organic fertiliser for the flowering and fruiting stage — the feed you switch to once buds and first flowers appear on tomatoes, peppers, roses, dahlias, strawberries and fruit. Low nitrogen keeps growth from running to leaf, while phosphorus drives flower and fruit set and potassium builds fruit quality and flower colour. Dr Forest blends it by hand in Stockport from eleven organic inputs, with a heavy dose of slow-release phosphorus and calcium from bone meal.
Bloom 2-8-4 is the flowering-stage partner to our All Purpose 4-4-4. Use the balanced 4-4-4 to build strong plants, then move to Bloom 2-8-4 as flowering begins to push blooms, fruit set and ripening. It is a granular dry amendment — sprinkle it on or mix it in, with no dissolving, no measuring pH and no weekly liquid feeding.
Because the nutrients come from organic meals and slow-release minerals rather than soluble salts, soil microbes release them at the pace the plant demands. Bone meal supplies the phosphorus and calcium; chloride-free sulphate of potash carries the fruit-quality potassium; and zeolite holds it all in the root zone rather than letting it wash away. Made with organic ingredients, compostable packaging, handcrafted in small batches.
When to reach for Bloom 2-8-4
- Fruiting vegetables — tomatoes, peppers, chillies, cucumbers, courgettes and aubergines from first flowers through to harvest, for more fruit and better ripening.
- Roses and flowering shrubs — bigger, longer-lasting blooms and repeat flowering across the season.
- Flowering ornamentals — dahlias, chrysanthemums, sweet peas, cosmos and bedding as buds form.
- Soft and tree fruit — strawberries, currants, gooseberries, raspberries, apples and pears at flowering and fruit set.
- Containers, baskets and patio pots — flowering displays that need steady phosphorus and potash without leaching.
- Switching from growth feed — the natural next step after All Purpose 4-4-4 once plants move from leafy growth into flower.
Organic bloom feed vs synthetic tomato feed
Dr Forest Bloom 2-8-4
- 11 organic inputs — slow-release phosphorus, potash and calcium
- Feeds through microbial breakdown at the rate plants demand
- Calcium built in — supports firm fruit and fewer disorders
- Builds soil biology and structure with every application
- No salt build-up; the soil improves rather than degrades
Typical synthetic bloom / tomato feed
- A few mineral salts, quickly used up
- A spike of availability, then run-off
- Usually no calcium and few trace minerals
- Bypasses the soil food web entirely
- Weekly mixing and measuring, with salt build-up over time
Handcrafted in small batches in Stockport, Greater Manchester, using British ingredients where possible, including Scottish seaweed. Made with organic ingredients, with no synthetic chemistry. Made by Growers. Backed by Science.
Eleven organic inputs, tuned for flower and fruit
This is a multi-input blend, not a two-part salt feed. Every ingredient earns its place — a primary nutrient, a secondary nutrient, or a biological function. Shares below are the proportion of the mix.
Bone meal
The engine of the blend and the reason it is high-phosphorus. Bone meal supplies phosphorus (around 18% P₂O₅) alongside a large calcium fraction, released slowly as soil acids and microbes work on it. Phosphorus drives flowering, fruit set and root development; calcium builds firm fruit and helps prevent disorders like blossom-end rot. Availability is best in slightly acidic to neutral soil. (Because it contains bone meal, this blend is not suitable for vegan gardening.)
Alfalfa meal
The organic-matter backbone. Alfalfa is the main source of plant-based carbon that soil microbes feed on and turn into humus, and it carries triacontanol, a natural growth promoter, plus a gentle dose of nitrogen and potassium. It keeps the soil biology fed without pushing leafy growth during flowering.
Zeolite
A natural volcanic mineral with an exceptionally high cation exchange capacity. Zeolite acts as a nutrient and moisture reservoir in the root zone, holding potassium, ammonium and calcium against leaching and releasing them slowly to the roots. It also improves aeration in heavier soils and container mixes — so more of the feed reaches the plant and less washes away.
Sulphate of potash
Chloride-free potassium (50% K₂O) with sulphur alongside. Potassium is the fruit-and-flower nutrient — it governs sugar movement, fruit quality, flower colour and water regulation, and the sulphate form avoids the chloride that fruiting crops dislike.
Kieserite
Magnesium sulphate — a steady source of magnesium and sulphur. Magnesium sits at the centre of every chlorophyll molecule, keeping foliage green and photosynthesis strong through fruiting; sulphur supports protein and flavour compound synthesis.
Gypsum
Calcium sulphate — a pH-neutral source of extra calcium and sulphur. It reinforces fruit firmness and cell-wall strength without shifting soil pH, and helps open up heavier soils.
Flaxseed meal
Cold-pressed linseed meal adds organic matter and oils that feed the soil microbiome, plus a small, slow trickle of nitrogen to keep plants ticking over without forcing leaf.
Scottish seaweed
Cold-water Ascophyllum nodosum from the Scottish coast. A biostimulant rather than a headline nutrient source, it supplies cytokinins, auxins, alginates and trace elements that support flowering, fruit set and stress tolerance.
Humic & fulvic acid
Humic acid improves soil structure and root growth; fulvic acid is a low-molecular-weight chelator that binds micronutrients into forms roots can take up. A little goes a long way at flowering, when demand for trace elements rises.
Nitrogen plant extract
A concentrated plant nitrogen (around 13% N), derived from molasses and rich in amino acids. Kept deliberately low in a bloom feed — just enough to sustain the plant without pushing the soft, leafy growth that comes at the expense of flowers.
Fermented biochar
Pyrolysed carbon with a vast internal surface that houses beneficial microbes. Pre-fermented so it is biologically active from day one, it works alongside the zeolite to hold nutrients in the root zone and reduce leaching under heavy watering or rain.
When and how to feed with Bloom 2-8-4
Move to Bloom 2-8-4 as flower buds form and the first flowers open. Before that, use a balanced feed such as All Purpose 4-4-4 for growth. On perennials and roses, start in spring as growth resumes and feed through the flowering season.
Soil mix (before planting or potting on): 5–10 g per litre of soil or compost, worked in thoroughly. Top dress (during flowering and fruiting): 2–4 g per litre of soil, scattered on the surface and watered in. A level tablespoon holds roughly 12–15 g.
Fruiting vegetables
Tomatoes, peppers, chillies, cucumbers, courgettes and aubergines. Start as the first trusses or flowers set and continue through cropping. Water in well — steady phosphorus and potash mean more fruit and better ripening.
Roses, flowering shrubs and ornamentals
Roses, dahlias, chrysanthemums, sweet peas and flowering shrubs. Scatter around the base and lightly work in. Feeds bigger, longer-lasting blooms and encourages repeat flowering.
Soft and tree fruit
Strawberries, currants, gooseberries, raspberries and top fruit such as apples and pears. Apply as flowering starts and again as fruit sets for size and sweetness.
Containers, baskets and outdoor beds
For beds and borders, scatter and work lightly into the top 5–10 cm. For pots and baskets, mix in at planting and top dress as flowering continues. A handful is roughly 40–50 g.
Step by step
- Grow first, then flower. Build the plant with a balanced feed, then switch to Bloom 2-8-4 as buds and first flowers appear.
- Apply. Mix into compost at potting, or top dress around the base of established plants at the rates above.
- Water in. Moisture activates the soil biology that releases the nutrients.
- Keep it going. Top dress on the frequency for the plant type, right through flowering and fruiting.
- Ease off at the end. Stop feeding as crops finish or plants move towards dormancy.
1. Switching too early — feed for growth first, bloom once flowering starts. 2. Expecting an overnight response — this feeds over weeks, not hours. 3. Underfeeding pots — confined roots and frequent watering empty a container fast. 4. Applying to bone-dry soil — always water in. 5. Feeding on past the end of cropping — ease off as plants finish.
Follows on from All Purpose 4-4-4 once plants move into flower. Pair with Sulphate of Potash for an extra potash lift on tomatoes and fruit, and with Seaweed Plant Food for biostimulant support during heat or fruit set.
Keep the bag sealed in a cool, dry place. As a natural product it may vary slightly in colour and texture between batches. It contains bone meal, which some dogs find tempting, so store out of reach of children and pets.
Why high phosphorus and low nitrogen suit the flowering stage
As a plant moves from growth into flower, its needs change. High nitrogen keeps a plant producing leaves; easing nitrogen back and lifting phosphorus and potassium steers that energy into flowers and fruit instead. A 2-8-4 ratio does exactly that — modest nitrogen, a strong phosphorus lead, and enough potassium to build fruit quality.
Because the nutrients are held in organic matter and slow-release minerals rather than soluble salts, soil microbes release them as the plant's roots call for them, and the zeolite and biochar hold them in the root zone between waterings.
Mechanisms of action
Phosphorus for flower and fruit set
Bone meal makes this a phosphorus-led feed (around 18% P₂O₅ in the ingredient, and by far the largest share of the blend). Phosphorus is the core of ATP, the plant's energy currency, and drives root development, flowering and fruit set. Bone-meal phosphorus is released slowly as soil acids and microbes act on it, best in slightly acidic to neutral soil (Penn & Camberato, 2019).
Chloride-free potash for fruit quality
Sulphate of potash (50% K₂O) delivers potassium in a chloride-free form with sulphur alongside. Potassium regulates water movement and sugar transport, so it governs fruit size, sweetness and flower colour — the nutrient fruiting and flowering crops draw down hardest, and one that sulphate-sensitive crops such as tomatoes and strawberries take best without chloride.
Calcium built in for firm fruit
Bone meal and gypsum together supply a generous calcium dose, with gypsum adding it in a pH-neutral form. Calcium builds strong cell walls and firm fruit and helps guard against calcium-related disorders such as blossom-end rot in tomatoes and peppers — where most liquid bloom feeds contain no calcium at all.
Low, steady nitrogen
Nitrogen is kept deliberately low and slow — a small amino-acid nitrogen extract plus what alfalfa and seaweed release through microbial mineralisation (Cassity-Duffey et al., 2020). Enough to sustain the plant, not enough to push the soft leafy growth that comes at the expense of flowers and fruit.
Zeolite holds the feed in place
Zeolite is a natural aluminosilicate mineral with a very high cation exchange capacity. It holds potassium, ammonium and calcium against leaching and releases them slowly to the roots, and improves aeration in heavier or container mixes — keeping more of the feed available through the flowering season rather than washing through after watering.
Seaweed and humic biostimulants
Scottish seaweed (Ascophyllum nodosum) supplies cytokinins, auxins and alginates; reviews of seaweed biostimulants report gains in growth, yield and crop quality across a range of crops (Khan et al., 2009; Ali et al., 2021). Alfalfa's triacontanol is linked to higher chlorophyll and photosynthetic rate (Naeem et al., 2012), and humic substances stimulate root growth and nutrient uptake (Nardi et al., 2002; Canellas & Olivares, 2014).
Biochar and living-soil feeding
Fermented biochar's vast internal surface provides habitat for soil microbes (Lehmann et al., 2011) and, with the zeolite, helps hold nutrients in the root zone. Feeding through the soil this way builds fertility rather than depleting it — across a global meta-analysis, organic fertilisation supported productivity while maintaining plant diversity where inorganic-only feeding did not (Shi et al., 2024).
Scientific references
- Penn, C. & Camberato, J. (2019). A critical review on soil pH and phosphorus availability. Agriculture, 9(6), 120.
- Cassity-Duffey, K. et al. (2020). Nitrogen mineralisation from organic materials and fertilisers. Soil Science Society of America Journal, 84, 522–533.
- Khan, W. et al. (2009). Seaweed extracts as biostimulants of plant growth and development. Journal of Plant Growth Regulation, 28, 386–399.
- Ali, O., Ramsubhag, A. & Jayaraman, J. (2021). Biostimulant properties of seaweed extracts in plants: implications towards sustainable crop production. Plants, 10(3), 531.
- Naeem, M. et al. (2012). Triacontanol: a potent plant growth regulator in agriculture. Journal of Plant Interactions, 7(2), 129–142.
- Nardi, S., Pizzeghello, D., Muscolo, A. & Vianello, A. (2002). Physiological effects of humic substances on higher plants. Soil Biology & Biochemistry, 34, 1527–1536.
- Canellas, L. & Olivares, F. (2014). Physiological responses to humic substances as plant growth promoter. Chemical and Biological Technologies in Agriculture, 1, 3.
- Lehmann, J. et al. (2011). Biochar effects on soil biota — a review. Soil Biology & Biochemistry, 43(9), 1812–1836.
- Shi, T.-S. et al. (2024). A global meta-analysis on the effects of organic and inorganic fertilization on grasslands and croplands. Nature Communications, 15, 3411.
Figures describe the published literature on these ingredient classes and are not product-specific yield guarantees.
Bloom 2-8-4 — frequently asked questions
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