Organic Bloom Booster 2-10-5 | Fast-Acting Soluble Powder | Dr Forest

Overview Ingredients How to Use The Science FAQ Organic Bloom Booster 2-10-5 — a fast-acting soluble powder for the exact moment a plant sets flower NPK 2-10-5 Solution Grade Fast Release Sulphate of Potash Kieserite Magnesium Fulvic Acid Seaweed Extract Just Add Water Bloom Booster 2-10-5 is a solution-grade powder built around the moment a plant shifts from leafy growth to flowering and fruiting. It makes up into a liquid solution when added to water, reaching the root zone within hours — a deliberately low-nitrogen, high-phosphorus ratio that supports flower and fruit development rather than more leaf. The phosphorus (micronised rock phosphate) and calcium (micronised gypsum) are milled to an ultra-fine particle size for fast breakdown, while nitrogen (amino acids) and potassium (Sulphate of Potash) go fully into solution. Magnesium now comes from Kieserite, a naturally mined mineral, in place of the Epsom salt used previously. Soluble seaweed extract and fulvic acid complete the formula — the fulvic acid chelates the minerals in the drench so the phosphorus and potassium are taken up more efficiently. This is a timed intervention, not a season-long feeding programme. It is applied at flowering and through fruit set — see Booster vs granular below, and the timing guide on the How to Use tab. 2-10-5Bloom NPK HoursTo Root Zone SOPPotassium Source KieseriteMagnesium Source What Bloom Booster is used for in the garden First flower trigger — the moment a tomato, chilli, courgette or bean plant sets its first bud is the signal to switch from a nitrogen-led feed to Bloom Booster Through fruit set and swell — repeated applications support the phosphorus and potassium demand of developing fruit Roses and flowering shrubs — a bud-to-bloom boost timed to flush cycles, for more flowers and stronger colour Strawberries and soft fruit — applied from flowering through fruiting for size and yield Orchids and container flowering plants — a gentle, low-rate feed timed to bud development Fruit trees — supports blossom and early fruit set in spring Reviving a reluctant flowerer — a plant that's leafy but won't bloom often responds to a lower-nitrogen, higher-phosphorus drench within days Booster vs granular — two different jobs Bloom Booster 2-10-5 (soluble powder, fast release) Mixes into a liquid solution — nutrients reach the root zone within hours Applied at the moment a plant sets flower, and through fruit set Concentrated powder — you add the water, no shipping weight No standing nutrient reserve in the soil between applications Organic Bloom Fertiliser 2-8-4 (granular, slow release) Breaks down over weeks as soil microbes and moisture work on it Applied at planting or on a schedule as the background feed for flowering and fruiting beds One application covers weeks, not one watering Builds a standing nutrient reserve — but can't respond to the exact day a plant sets flower The granular feeds the season. The Booster feeds the flower. All seven inputs — what they do and why each one is in the formula Bloom Booster's 2-10-5 ratio is deliberately low in nitrogen and high in phosphorus, so every input is chosen to support flower and fruit development without pushing more leaf. Two ingredients changed in this recipe: potassium now comes from Sulphate of Potash rather than a micronised potassium mineral, and magnesium now comes from Kieserite rather than Epsom salt. 01Micronised rock phosphate — phosphorus, the lead nutrient Phosphorus drives flower and root development and is the largest single input in this formula. Milling it to an ultra-fine particle size increases its reactive surface area so it starts releasing within days rather than sitting inert in the soil. 02Sulphate of Potash — potassium, fully soluble Sulphate of Potash (SOP) is roughly 50% K₂O and 18% sulphur, and it is genuinely chloride-free. It replaces the micronised potassium mineral used previously: because SOP dissolves completely in water, potassium — the nutrient that governs fruit quality, sugar transport and colour — is now fully soluble rather than split between a fast and a slow-release form. 03Amino acids — nitrogen, kept deliberately low and soluble A small, fast-acting nitrogen input that supports the plant without triggering the leafy growth that competes with flowering. Amino acids are absorbed directly by root transporters rather than waiting on microbial conversion. 04Micronised gypsum — calcium, fast-breaking mineral Calcium is essential for cell wall strength in developing fruit — a shortfall shows up as disorders like blossom end rot in tomatoes. The micronised form keeps pace with the fast phosphorus and potassium in this formula. 05Kieserite — magnesium, naturally mined mineral Kieserite (magnesium sulphate monohydrate) is roughly 25% MgO and 50% SO₃. It replaces the Epsom salt previously used in this formula. Magnesium sits at the centre of the chlorophyll molecule, and a shortfall during heavy fruiting shows up as interveinal yellowing on older leaves. As a mined mineral, Kieserite also contributes further sulphur to the feed. 06Soluble seaweed extract — hormones and trace minerals Natural cytokinins and auxins support fruit set and reduce flower and fruit drop under stress, alongside over 60 trace elements in immediately available form. 07Fulvic acid — chelation and uptake Fulvic acid is the smallest, most soluble fraction of humic substances. It chelates the mineral nutrients in the drench and increases root cell membrane permeability, so the phosphorus and potassium this formula relies on are absorbed more efficiently. How to use Bloom Booster: preparation, rates & timing Just add water — solution grade powderAdd the measured amount to water and stir briefly. The soluble fraction dissolves completely; the micronised fraction forms a fine, stable suspension. Mix fresh for each application — don't store the diluted solution. Application rates by plant Tomatoes, chillies & peppers Rate: ½ teaspoon (approx. 2.5g) per litre | Frequency: Weekly from first flower through fruit set Start the day the first truss sets flower and continue through harvest for consistent fruit development. Roses & flowering shrubs Rate: ¼–½ teaspoon per litre | Frequency: Every 2 weeks through each flush Timed to bud formation for stronger blooms and better colour through each flowering flush. Strawberries & soft fruit Rate: ¼ teaspoon per litre | Frequency: Weekly from flowering to fruiting Supports fruit size and yield through the flowering-to-fruiting window. Annuals & bedding plants Rate: ¼ teaspoon per litre | Frequency: Every 2 weeks through the flowering season Extends the flowering display and keeps colour going through the season. Orchids & container flowering plants Rate: ⅛ teaspoon (approx. 0.5g) per litre | Frequency: Every 2–4 weeks when in bud A gentle rate suited to sensitive container plants and orchid roots. Fruit trees Rate: ½ teaspoon per litre | Frequency: At blossom and again at early fruit set Two well-timed applications in spring support blossom retention and early fruit set. Step-by-step preparation Measure the powder. ¼ teaspoon (approx. 1g) per litre for sensitive plants, up to ½ teaspoon (approx. 2.5g) for heavy fruiters like tomatoes. Add to water and stir. The soluble fraction dissolves within seconds; the micronised fraction forms a fine suspension. Apply as a root drench. Saturate the root zone; for containers, apply until a little runs through the drainage holes. Use fresh. Mix only what you need — don't store the diluted solution. When timing matters more than scheduleUse the granular Bloom Fertiliser 2-8-4 as the background feed for a flowering or fruiting bed. Reach for Bloom Booster at the specific moment a plant sets its first flower — that's the trigger to switch — and keep applying through fruit set. Getting the timing right does more for flowering and fruit than an early or extra granular application. Works well combined with…Switch to Bloom Booster from All-Purpose Booster 5-5-5 the moment first flower appears. Use alongside the granular Bloom Fertiliser 2-8-4 as the base feed, with Booster as the liquid top-up through the flowering and fruiting window. Add Seaweed Powder to the same watering can to help reduce flower and fruit drop under stress. The science of fast-release feeding: why a soluble drench and a slow-release granular are not interchangeable Two release curves, two jobs A granular fertiliser like Bloom Fertiliser 2-8-4 is built to be slow. Its minerals are sized so that soil moisture and microbial activity break them down gradually over weeks, releasing a steady trickle of phosphorus and potassium that a bed can draw on through the season. That's the right behaviour for background feeding — but the release curve is fixed the moment the granules go down. It can't respond to the exact day a plant sets its first flower. Bloom Booster inverts that curve deliberately. Every input is chosen to dissolve or break down within hours to days: amino acid nitrogen and Sulphate of Potash go into solution completely; the micronised rock phosphate, gypsum and Kieserite are milled fine enough to behave as near-soluble. The result is a feed you apply because a plant has just crossed into flowering, not on a fixed calendar. Granular 2-8-4 — steady background supply Release rate fixed by particle size and soil biology at the time of application One application covers the whole bed for weeks Cannot be timed to the exact day a plant sets flower Builds a standing reserve in the soil Bloom Booster — on-demand pulse Release rate is hours, regardless of soil biology Applied in direct response to first flower and fruit set Can be layered on top of a granular feed without disrupting it No standing reserve — nutrients are used or leached within days Why sulphate of potash matters more in a bloom formula Potassium regulates the movement of sugars into developing fruit and governs fruit quality, firmness and colour — arguably the nutrient with the most direct effect on the finished crop in a bloom feed. The mineral this formula used previously was micronised but still part of the slower-breaking fraction. Sulphate of Potash is a genuinely soluble salt, so switching to it puts the full potassium supply into solution alongside the phosphorus, meaning both arrive at the root zone together at the moment they're needed most. Five mechanisms of action 01Phosphorus for Flower & Root Development Phosphorus is central to the energy transfer (ATP) that drives cell division in developing flower buds and roots — the reason this formula leads with it. 02Soluble Potassium for Fruit Quality Potassium activates the enzymes that load sugars into fruit and regulates stomatal function, affecting firmness, sweetness and colour. Delivering it in fully soluble form means it's available exactly when fruit is filling. 03Sulphur From Two Mineral Sources Sulphate of Potash and Kieserite both carry sulphur alongside their headline nutrient — a component of several enzymes and of chlorophyll synthesis, easy to under-supply in a simple N-P-K view of feeding. 04Fulvic Acid Chelation & Membrane Transport Fulvic acid wraps mineral nutrients in a form that resists binding to soil particles and increases root cell membrane permeability, improving uptake of the phosphorus and potassium this formula relies on. 05Calcium & Magnesium Alongside Fast Phosphorus Fast-developing fruit has a high calcium demand — a shortfall shows as blossom end rot in tomatoes — while magnesium sits at the centre of the chlorophyll molecule. Micronised gypsum and Kieserite are included to keep pace with the phosphorus-driven fruiting response. Scientific References Marschner, H. (2012). Mineral Nutrition of Higher Plants (3rd ed.). Academic Press. Taiz, L. & Zeiger, E. (2015). Plant Physiology and Development (6th ed.). Sinauer Associates. Ho, L.C. & White, P.J. (2005). A cellular hypothesis for the induction of blossom-end rot in tomato fruit. Annals of Botany, 95(4), 571–581. Canellas, L.P. & Olivares, F.L. (2014). Physiological responses to humic substances as plant growth promoters. Chemical and Biological Technologies in Agriculture, 1(1), 3. Shukla, P.S. et al. (2019). Ascophyllum nodosum-based biostimulants. Frontiers in Plant Science, 10, 655. Lambers, H. et al. (2006). Root structure and functioning for efficient acquisition of phosphorus. Annals of Botany, 98(4), 693–713. Frequently asked questions about Bloom Booster Why use Bloom Booster instead of the granular Bloom Fertiliser 2-8-4?They do different jobs. The granular 2-8-4 breaks down over weeks and is the steady background feed for a flowering or fruiting bed. Bloom Booster dissolves within hours and is for the specific moment a plant crosses into flowering — a granular can't respond to that exact day. Use the granular on schedule and the Booster from first flower onward; they're not competing for the same job. When exactly should I start using Bloom Booster?At first flower — the moment a plant sets its first bud. That's the trigger to switch from a nitrogen-led feed (or All-Purpose Booster 5-5-5) to Bloom Booster, and to keep applying through fruit set. What changed with the potassium source, and does it matter?The previous formula used a micronised potassium mineral, part of the slower-breaking fraction. Sulphate of Potash is a genuinely soluble salt, so the whole potassium supply — the nutrient most directly linked to fruit quality and colour — now dissolves alongside the phosphorus instead of being split across two release speeds. It's also chloride-free and brings a useful dose of sulphur with it. What is Kieserite, and why replace Epsom salt with it?Kieserite is a naturally mined magnesium sulphate mineral, roughly 25% MgO and 50% SO₃. It sits alongside the gypsum and rock phosphate as a mined mineral input rather than a refined salt, and contributes further sulphur to the feed. The magnesium content and role in the formula are unchanged. Why is the nitrogen so low compared to All-Purpose Booster?Nitrogen drives leafy growth, which competes with flowering and fruiting for the plant's resources. Bloom Booster's 2-10-5 ratio deliberately keeps nitrogen low and leads with phosphorus, to push energy towards flowers and fruit rather than more leaf. My tomato plant is leafy but won't flower — will this help?Often, yes. Excess nitrogen relative to phosphorus is a common cause of a leafy plant that won't set flower. A drench of Bloom Booster shifts that balance and typically shows a response within one to two weeks. Can I use it on roses and ornamental flowers, not just fruiting crops?Yes. The same fast phosphorus-and-potassium profile that supports fruit set also supports bud formation and flower colour in roses and other ornamentals — apply every two weeks through each flowering flush. Why does it contain calcium and magnesium as well as NPK?Developing fruit has a high calcium demand — a shortfall shows up as blossom end rot in tomatoes — and magnesium sits at the centre of chlorophyll. The micronised gypsum and Kieserite keep pace with the phosphorus-driven fruiting response. What does the fulvic acid do?Fulvic acid is a small, water-soluble humic substance. In the drench it binds to the mineral nutrients so they are less likely to lock up in the soil, and it increases root cell membrane permeability. It carries no NPK of its own; its job is to help the phosphorus and potassium get taken up. Is it safe for orchids and other sensitive container plants?Yes, at the lower rate (⅛ teaspoon per litre). The gentle amino acid nitrogen and balanced mineral profile suit sensitive root systems. Is it a replacement for a bottled liquid tomato feed?It does the same job more efficiently. Bottled liquid feeds are typically 85–95% water by weight, so you're paying to ship water and a plastic bottle. Bloom Booster is a concentrated powder — you add the water at home. Can I mix it with other Dr Forest products?Yes. It's designed to sit alongside a granular base feed such as Bloom Fertiliser 2-8-4, and combines well with Seaweed Powder in the same watering can. How should I store it?Keep the dry powder sealed in a cool, dry place away from direct sunlight and moisture. If it absorbs moisture and clumps, it's still usable — break up the clumps and measure as normal. Don't pre-mix and store the diluted solution.