Organic Liquid Fertiliser 3-2-6 | High Potash Bloom Feed

Overview The Science How to Use FAQ Organic liquid fertiliser 3-2-6: high potash bloom and fruiting feed NPK 3-2-6 Plus magnesium Trace elements Clear solution Plant-based Foliar or root Liquid fertiliser 3-2-6 is a high potash natural plant food for the flowering and fruiting end of the season. Potassium runs at 6% against nitrogen at 3%, twice as much potash as nitrogen, which is the shape a plant needs once it stops building leaf and starts filling fruit. Magnesium and trace elements are included, so a long fruiting run does not end in the interveinal yellowing that heavy potash feeding otherwise provokes. This is the feed for bedding plants and hanging baskets in full flower, for petunias, busy lizzies, begonias, geraniums and trailing lobelia, for the second half of a tomato season, for strawberries in fruit and for dahlias and roses in bloom. The nitrogen is deliberately restrained. Late nitrogen is the most common reason a basket runs to leaf in August, and the most common reason a tomato plant carries magnificent foliage and disappointing trusses. Nutrients are in true solution rather than suspension: nothing settles, nothing needs shaking, nothing blocks a nozzle. Everything in it is plant-derived. 3%Nitrogen (N) 1.8%Phosphorus (P₂O₅) 6%Potassium (K₂O) 3.5 – 4.5pH What to use a 3-2-6 bloom feed for Tomatoes, peppers, chillies and aubergines from first fruit set — the classic high-potash tomato feed application. Potassium drives sugar transport into fruit, which is what determines how the crop actually tastes rather than only how large it grows Strawberries, raspberries, currants and gooseberries in fruit — berry crops respond to potassium in soluble solids and in the sugar-to-acid balance. Feed from flowering through picking Roses, dahlias and cut flower borders — potassium stiffens stems and supports repeat flowering through late summer. The nitrogen is low enough not to push soft growth in August Bedding plants, hanging baskets and patio containers — petunias, surfinias, calibrachoa, busy lizzies, begonias, geraniums, lobelia, bacopa and trailing verbena flower continuously from June to the first frosts. That is a heavy, sustained potassium demand in a very small volume of compost, and it is the point where a general-purpose feed starts producing leaf instead of bloom Bedding in borders and window boxes — French and African marigolds, antirrhinums, salvias, nicotiana, alyssum and osteospermum all keep flowering longer on a high potash feed. Pansies and violas carry the same principle through autumn and winter displays Potatoes from flowering through to lifting — one of the highest potassium-demanding crops on the plot, and one that responds to steady supply through tuber fill Top fruit through fruit development — apples, pears and plums during the fill period, tapering off before harvest Building resilience going into late season — potassium regulates stomatal control and osmotic adjustment, which is what keeps a plant standing up through a hot dry August Where 3-2-6 sits against the alternatives Liquid 3-2-6 bloom feed Potassium at double the nitrogen, the correct shape for flowering and fruiting Magnesium and trace elements included, so heavy potash feeding does not induce a secondary deficiency True solution, so nothing settles and it runs clean through drip lines and sprayers Plant-derived rather than mined or manufactured Root drench or foliar spray from the same bottle Ordinary tomato feed Usually a similar high-potash shape, and effective as far as it goes Commonly built on muriate of potash, which is roughly half chloride by weight Chloride accumulates in grow bags and pots across a season Magnesium and trace elements often absent Continuing a balanced feed into fruiting Too much nitrogen for the stage, so it pushes leaf rather than fruit Delays ripening and softens tissue The single most common feeding mistake in a British greenhouse The handover point Run liquid 5-2-5 through vegetative growth, then switch to this feed at first flower or first fruit set. That handover is the whole point of stage feeding: the plant's demands change, so the feed changes with them. Blended and bottled in small batches, made with organic ingredients and plant-based throughout. Made by Growers. Backed by Science. The science behind a high potash bloom feed The shift from vegetative growth to flowering is one of the sharpest changes in a plant's nutritional life. Demand for nitrogen falls because the plant has largely finished building tissue. Demand for potassium climbs steeply, because potassium is what moves the products of photosynthesis out of the leaf and into developing fruit (Marschner, 2012; Zörb et al., 2014). Nitrogen decides how big the plant gets. Potassium decides what the fruit tastes like. What each element is doing at this stage 01 Potassium — phloem loading Sucrose moves from leaf to fruit through the phloem, driven by a proton gradient that depends on potassium. This is the direct mechanistic link between potash supply and fruit sugar content, and it is why a high-potash feed changes flavour rather than only size (Zörb et al., 2014). 02 Potassium — water regulation under late-season stress Guard cells open and close by moving potassium, so potassium supply determines how well a plant manages water loss through a hot August. Deficient plants wilt sooner and recover more slowly (Hasanuzzaman et al., 2018). 03 Nitrogen — held deliberately low At 3%, enough to maintain the canopy without pushing new vegetative growth. Excess nitrogen during fruiting delays ripening, produces soft thin-walled tissue and diverts resources into leaf that should be going into fruit. 04 Phosphorus — steady through flowering At 1.8%, supporting the energy demands of flowering and seed set without the surplus that suppresses mycorrhizal association (Smith & Read, 2008). 05 Magnesium — the antagonist problem Potassium and magnesium compete for the same root uptake sites. Sustained high-potash feeding readily induces magnesium deficiency even where soil magnesium is adequate. Including magnesium in the feed itself is the fix. 06 Trace elements — boron and fruit set Boron is directly involved in pollen tube growth and fruit set, and is one of the trace elements most easily depleted in containers. Iron, manganese, zinc, copper and molybdenum are included alongside it. Why the nitrogen is low, in practical terms Every greenhouse in Britain contains at least one tomato plant six feet tall with beautiful dark foliage and three sad trusses. The usual cause is a balanced feed continued past first fruit set. Nitrogen promotes vegetative growth, and a plant given the option will keep growing rather than ripening. Dropping nitrogen and raising potassium is how you tell it to change priority. The same logic applies to flowering ornamentals. Late nitrogen on dahlias produces leaf; potassium produces bloom and stem strength. Chloride, containers and salt load Most cheap potash comes from muriate of potash, close to half chloride by weight. In open ground rainfall flushes chloride through. In a grow bag it does not, and tomatoes, strawberries and potatoes are all measurably chloride-sensitive (Xu et al., 2000). A plant-derived potassium source avoids adding chloride to a root zone that already has no way of clearing it. Solution rather than suspension The nutrients are dissolved, not suspended. Roots and leaf cuticles absorb ions, not particles, so a true solution is taken up on contact with no dissolution lag. It also means the same product sprays cleanly, because foliar uptake happens through cuticular pores far too small for suspended mineral to pass. The evidence on organic and mineral feeding Across 537 fertilisation experiments worldwide, organic amendment raised aboveground biomass by 56% against 42% under mineral fertilisation, and only the mineral treatments cost plant diversity in the grassland trials. Organic inputs also lifted soil organic carbon by 19% (Shi et al., 2024). Combined organic and mineral feeding produced the best crop quality across 7,859 paired data points (Wang et al., 2023). Work on organic fertilisation and carbohydrate metabolism found all 21 starch and sucrose pathway genes upregulated under organic inputs (Li et al., 2024), which is at least consistent with the fruit quality effects growers report. References Marschner, P. (ed.) (2012). Marschner's Mineral Nutrition of Higher Plants, 3rd edition. Academic Press. Zörb, C., Senbayram, M. & Peiter, E. (2014). Potassium in agriculture — status and perspectives. Journal of Plant Physiology, 171(9), 656–669. Hasanuzzaman, M. et al. (2018). Potassium: a vital regulator of plant responses and tolerance to abiotic stresses. Agronomy, 8(3), 31. Smith, S.E. & Read, D.J. (2008). Mycorrhizal Symbiosis, 3rd edition. Academic Press. Xu, G., Magen, H., Tarchitzky, J. & Kafkafi, U. (2000). Advances in chloride nutrition of plants. Advances in Agronomy, 68, 97–150. 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. Wang, X. et al. (2023). Combined organic and mineral fertilisation and crop quality: a synthesis of 7,859 data pairs. Li, Y. et al. (2024). Organic fertilisation and starch/sucrose metabolism gene expression. Scientific Reports. How to use liquid 3-2-6 bloom feed Before you start Measure with a syringe or small measuring cup rather than pouring by eye. The concentrate is acidic at pH 3.5 to 4.5, which keeps the nutrients soluble. Always dilute into water, never apply neat. Keep the cap tight between uses to prevent moisture loss. Application rates Root drench — fruiting and flowering crops Rate 3–6 ml per litre of water | Frequency every watering Delivers roughly 180 to 360 mg/l of K₂O against 90 to 180 mg/l of nitrogen. Use the upper end for tomatoes and heavy fruiting crops in full production, the lower end for ornamentals and general border feeding. Root drench — open ground and plot Rate 3–6 ml per litre of water | Frequency weekly Same dilution applied once a week rather than every watering. Suits potatoes from flowering, soft fruit in the ground and established flowering borders. Foliar spray Rate 3–5 ml per litre of water | Frequency 3–4 applications per season Spray to run-off in early morning or evening, never in strong sun. Useful for a fast top-up when roots are limited by cold or waterlogged ground, or when potassium deficiency is already visible on older leaves. Mixing Half-fill the watering can or sprayer with water first. Measure the dose with a syringe and add it to the water. Top up to full volume and stir or agitate briefly. Apply the same day. Diluted feed is not worth keeping. Rinse equipment through with clean water afterwards. When to switch to this feed Crop Switch point Continue until Tomatoes, peppers, aubergines First fruit set Last truss ripens Strawberries and cane fruit First flower End of picking Potatoes First bloom Haulm dies back Roses and dahlias First bud colour Late September Bedding, baskets and window boxes 2 to 3 weeks after planting out First frosts Apples, pears, plums After fruit set Four weeks before harvest Watch the lower leaves Sustained high-potash feeding can induce magnesium deficiency, which shows as yellowing between the veins on older leaves while the veins themselves stay green. Magnesium is included in this formulation to head that off, but on very long tomato runs in pots keep an eye on the bottom of the plant and add a magnesium source if it starts to show. Storage Cap tight to prevent moisture loss. Store dark and dry between 10 and 25 °C. Shelf life 18 months to 2 years. Do not let it freeze. What to pair it with Pair this with the rest of the Dr Forest liquid range. Liquid Seaweed Biostimulant covers alginates and natural growth promoters that a straight nutrient feed does not. Liquid Gypsum supplies calcium and sulphur, the two things most liquid feeds leave out. Micro 7 chelated micronutrients fills the trace element gap on long cropping runs. For a full-season plan, see the Dr Forest feeding programme. Liquid 3-2-6 bloom feed — common questions What is a 3-2-6 fertiliser and what is it for? It is a high potash liquid feed with 3% nitrogen, 1.8% phosphorus as P₂O₅ and 6% potassium as K₂O, plus magnesium and trace elements. Potassium at double the nitrogen is the shape a plant needs once it moves from building leaf to filling fruit or holding flower. Is this the same as a tomato feed? It does the same job and is used the same way. The differences are that it is plant-derived rather than built on mineral salts, it carries essentially no chloride, and magnesium and trace elements are included rather than left out. When exactly should I switch to it? At first fruit set on fruiting crops, at first flower on ornamentals. Before that point use a balanced growth feed such as liquid 5-2-5. Switching too late is the usual reason a tomato plant carries superb foliage and a poor crop. Why is the P shown as 2 when the analysis says 1.8%? NPK figures on labels are conventionally rounded. The precise analysis is 1.8% P₂O₅ and we have printed that in the composition rather than only the rounded shorthand. Can I use it on flowers as well as fruit? Yes. Roses, dahlias, hanging baskets and container displays all benefit. Potassium supports repeat flowering and stem strength, and the low nitrogen avoids pushing soft growth in late summer. Is this a good feed for bedding plants and hanging baskets? It is the right shape for them. Petunias, surfinias, calibrachoa, busy lizzies, begonias, geraniums, lobelia and bacopa all flower continuously for four months from a few litres of compost, which is a heavy potassium demand in a very small root volume. Marigolds, antirrhinums, salvias and osteospermum respond the same way. The low nitrogen is the point: it keeps the display flowering rather than running to leaf. When should I start feeding bedding plants with it? Once flowering is properly under way, usually two to three weeks after planting out. Before that a balanced growth feed helps the plants root into the compost. Most multi-purpose compost carries only four to six weeks of nutrition, so baskets and containers planted in May are running short by mid-June whatever they look like. How often should I feed a hanging basket? At every watering, at 3 to 6 ml per litre, through the flowering season. Baskets dry out and get watered daily in summer, which flushes nutrients straight through the compost. Little and often at feeding strength suits them far better than a heavy dose once a fortnight. Deadhead as you go and the display will carry on to the first frosts. Can I use it as a foliar spray? Yes, at 3 to 5 ml per litre, three to four times a season. The nutrients are in true solution rather than suspension, so they pass through the leaf cuticle. Spray early morning or evening, never in strong sun. Will heavy potash feeding cause magnesium deficiency? It can. Potassium and magnesium compete for the same uptake sites at the root, so sustained high-potash feeding sometimes induces magnesium shortage even where soil magnesium is fine. Magnesium is included here to reduce that risk. On very long container runs, watch the lower leaves for interveinal yellowing. Does it contain chloride? Essentially none. Most cheap potash is muriate of potash, close to half chloride by weight, which accumulates in grow bags and pots across a season. Tomatoes, strawberries and potatoes are the crops that show chloride sensitivity first. Can I mix it with other Dr Forest liquids? It combines well with seaweed and with the single-nutrient liquid feeds. Do not combine any phosphorus-containing feed with a calcium product in the same can, because the two precipitate on contact. Is it safe around children, pets and wildlife? It is a plant-derived nutrient solution with no pesticide content. The concentrate is acidic, so keep it capped and out of reach and wash hands after handling. Treated ground is fine once watered in. Is this an organic fertiliser? It is made with organic ingredients and is plant-based throughout. Dr Forest does not hold organic certification for its products, so we say made with organic ingredients rather than certified organic.