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How Liquid Seedling Fertiliser compares
Full guide and scienceDr Forest Liquid Seedling Fertiliser
- Calcium-led at 4.13%, for the cell walls of new root tips
- Iron, zinc, manganese and molybdenum at seedling-scale doses, with fulvic acid as a natural chelator
- Humic and fulvic acids for root branching and water uptake through the seed coat
- Safe for direct seed contact at 3 to 3.5 ml per litre
- One bottle, three jobs: soak, dip, drench
General-purpose liquid feed, watered down
- Nitrogen-led, so it favours leaf over root at the stage roots matter most
- Most liquid feeds carry no calcium at all
- Diluting a strong feed enough to be seed-safe leaves the trace elements at background levels
- No humic or fulvic fraction
- Formulated for an established plant with a working root system
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Made by Growers · Backed by Science
Liquid fertiliser for seedlings: a calcium and micronutrient root starter for seed soaks, dips and drenches
4.13% Calcium Fe · Zn · Mn · Mo Humic & Fulvic Acid Seed Soak & Drench Recycled Plastic Bottle Handcrafted in Stockport
This liquid fertiliser for seedlings is a starter feed, built around calcium, four micronutrients and humic and fulvic acids, for the first two to four weeks of a plant's life. A germinating seed builds its first root tips and cell walls from a small store of reserves, and this feed puts calcium, zinc, manganese and molybdenum next to the new root from the start. Dr Forest makes it as a thick, calcium-rich suspension (4.13% Ca) for a seed soak before sowing or a drench straight after planting, both at 3 to 3.5 ml per litre, and for a root dip at transplanting at 10 ml per litre.
It is a low-nitrogen seedling feed on purpose. Young plants want roots before leaves, and a nitrogen-led liquid pushes the wrong end of the plant. It comes in 500 ml and 1 litre recycled plastic bottles.
4.13%Calcium (Ca)
1.24%Sulphur (S)
Fe Zn Mn MoMicronutrients
3–3.5 ml/LSeed soak & drench rate
What a seedling fertiliser is used for in the garden
- Seed soaking before sowing — 6 to 12 hours in the diluted feed puts calcium, micronutrients and humic substances on and in the seed coat before it goes in the compost.
- Root dip at transplanting — a 10 to 30 second dip coats bare roots with a nutrient film as they go into their final position.
- Root drench after sowing or planting out — 1 litre of diluted feed per m² puts calcium where the first root tips will reach it.
- Better germination and emergence — in a published trial, seed soaked in manganese or zinc sulphate germinated and emerged better than untreated seed (see The Science).
- Bigger root systems — in a meta-analysis of published trials, humic substances raised root dry weight by about a fifth on average.
- Module trays, seed beds and plug plants — anything raised from seed or planted out young: tomatoes, chillies, brassicas, salads, beans, sweetcorn and bedding.
Why a dedicated seedling feed rather than a diluted general-purpose liquid?
Dr Forest Liquid Seedling Fertiliser
- Calcium-led at 4.13%, for the cell walls of new root tips
- Iron, zinc, manganese and molybdenum at seedling-scale doses, with fulvic acid as a natural chelator
- Humic and fulvic acids for root branching and water uptake through the seed coat
- Safe for direct seed contact at 3 to 3.5 ml per litre
- One bottle, three jobs: soak, dip, drench
General-purpose liquid feed, watered down
- Nitrogen-led, so it favours leaf over root at the stage roots matter most
- Most liquid feeds carry no calcium at all
- Diluting a strong feed enough to be seed-safe leaves the trace elements at background levels
- No humic or fulvic fraction
- Formulated for an established plant with a working root system
Handcrafted in Stockport
Every Dr Forest product is made by hand in small batches at our workshop in Stockport, Greater Manchester, with organic ingredients where they exist. If you want the background on the humic and fulvic fraction, read Humic vs fulvic acid: the difference, and which you need. Made by Growers. Backed by Science.
The Science
The science of seedling nutrition: why the first fortnight is a calcium and trace-element problem
What is in the bottle
A thick brown suspension (SG 1.1, pH 8 to 9) carrying calcium and sulphur as the main minerals, a background of potassium and magnesium, four micronutrients and a humic and fulvic acid fraction. Nitrogen and phosphorus are not declared in the analysis. It goes on at sowing and planting out, and a crop-specific feed takes over once the seedlings are established.
The humic acids work on the root (mechanism 04 below). The fulvic acid is a natural chelator that helps keep iron, zinc and manganese in plant-available form in the compost immediately around the seed. There is a longer explanation in What is fulvic acid?.
Analysis
| Element | Content | Role in the seedling |
|---|---|---|
| Calcium (Ca) | 4.13% | Cell wall cross-linking; root tip and shoot tip growth |
| Sulphur (S) | 1.24% | Sulphur amino acids and proteins |
| Potassium (K), organic | 2,667 mg/L | Cell turgor and water regulation |
| Magnesium (Mg) | 734 mg/L | Chlorophyll core once the cotyledons green |
| Iron (Fe) | 160 mg/L | Chlorophyll synthesis; electron transport |
| Zinc (Zn) | 71 mg/L | Auxin (IAA) levels in growing shoots; part of thousands of proteins |
| Manganese (Mn) | 64 mg/L | Water-splitting in photosystem II; enzyme activation |
| Molybdenum (Mo) | 8 mg/L | Nitrate reductase cofactor |
Calcium and sulphur are declared as percentages and the remaining elements in milligrams per litre, as in the guaranteed analysis. At the 3 to 3.5 ml per litre soak and drench rate, each litre of diluted solution carries roughly 125 to 160 mg of calcium, half a milligram of iron and 0.02 to 0.03 mg of molybdenum: seedling-scale quantities, deliberately.
A seedling cannot borrow calcium from an old leaf. It has to be at the root tip when the root tip is growing.
Mechanisms of action
01
Soaking seeds in micronutrient solutions raises germination and emergence
Farooq, Wahid and Siddique (2012, Journal of Soil Science and Plant Nutrition) reviewed the seed-treatment literature. Priming echinacea seed in a 0.1% manganese sulphate solution raised germination by 36% and field emergence by 27%, and a 0.05% zinc sulphate soak raised them by 38% and 41%. Across 48 trials in eastern India, molybdenum applied by seed priming lifted mean yield by 17 to 22% over the no-molybdenum control. Those trials used single-nutrient solutions at their own strengths; read the figures as the direction of the effect.
02
A seed soak is a simple form of priming
Paparella and colleagues (2015, Plant Cell Reports) describe priming as controlled water uptake that switches on pre-germinative metabolism, including DNA repair and antioxidant pathways, stopped before the radicle breaks through. A 6 to 12 hour soak, drained and sown straight away, works on the same principle.
03
Calcium is immobile, so it has to arrive with the root
Calcium cross-links the pectin in the middle lamella, the cement between new cells, and it is poorly remobilised from old tissue through the phloem (Thor, 2019, Frontiers in Plant Science). Young tissue therefore depends on a fresh supply carried up in the xylem with the transpiration stream, and young tissue does not transpire much, so the supply is thin. A germinating seed is nearly all young tissue, which is why this feed puts calcium on the seed coat and in the top layer of compost, where the first root tips grow.
04
Humic substances increase root growth
A meta-analysis of published trials (Rose et al., 2014, Advances in Agronomy) put the average response to humic substances at +22% shoot dry weight and +21% root dry weight, with wide variation by source and rate. Nardi and colleagues (2002, Soil Biology and Biochemistry) reviewed evidence that the low molecular size fraction stimulates the plasma membrane H⁺-ATPase and has auxin-like activity, and noted that the increase in root growth is generally more apparent than that of the shoot. Jindo et al. (2012, Plant and Soil) found the same root and proton pump response in four-day-old maize seedlings. Canellas et al. (2015, Scientia Horticulturae) tie the bioactivity specifically to lateral root promotion and nutrient uptake.
05
Zinc-deficient shoots run short of auxin
In zinc-deficient bean, indole-3-acetic acid in the shoot tips and young leaves fell to about half the level in zinc-sufficient plants, and shoot growth was severely depressed; resupplying zinc restored both within 96 hours (Cakmak, Marschner and Bangerth, 1989, Journal of Experimental Botany). Zinc is a component of thousands of plant proteins and zinc-limited crop growth is widespread (Broadley et al., 2007, New Phytologist). Zinc also locks up in alkaline and high-phosphate soils, which is the reason for the fulvic acid alongside it.
06
Molybdenum: a shortfall that can pass for nitrogen deficiency
Molybdenum is a cofactor of nitrate reductase, the enzyme that turns absorbed nitrate into something the plant can build protein from. Kaiser and colleagues (2005, Annals of Botany) describe its importance as disproportionate to the tiny amounts required, and note that the deficiency is often misdiagnosed and put down to its downstream effects, nitrogen metabolism among them. A seedling short of molybdenum can look short of nitrogen, and extra nitrate will not help while the enzyme lacks its cofactor.
Scientific references
- Farooq, M., Wahid, A. & Siddique, K.H.M. (2012). Micronutrient application through seed treatments: a review. Journal of Soil Science and Plant Nutrition, 12(1), 125–142.
- Paparella, S., Araújo, S.S., Rossi, G., Wijayasinghe, M., Carbonera, D. & Balestrazzi, A. (2015). Seed priming: state of the art and new perspectives. Plant Cell Reports, 34(8), 1281–1293.
- Thor, K. (2019). Calcium—nutrient and messenger. Frontiers in Plant Science, 10, 440.
- Rose, M.T., Patti, A.F., Little, K.R., Brown, A.L., Jackson, W.R. & Cavagnaro, T.R. (2014). A meta-analysis and review of plant-growth response to humic substances: practical implications for agriculture. Advances in Agronomy, 124, 37–89.
- Nardi, S., Pizzeghello, D., Muscolo, A. & Vianello, A. (2002). Physiological effects of humic substances on higher plants. Soil Biology and Biochemistry, 34(11), 1527–1536.
- Jindo, K., Martim, S.A., Navarro, E.C., Pérez-Alfocea, F., Hernandez, T., Garcia, C., Aguiar, N.O. & Canellas, L.P. (2012). Root growth promotion by humic acids from composted and non-composted urban organic wastes. Plant and Soil, 353(1–2), 209–220.
- Canellas, L.P., Olivares, F.L., Aguiar, N.O., Jones, D.L., Nebbioso, A., Mazzei, P. & Piccolo, A. (2015). Humic and fulvic acids as biostimulants in horticulture. Scientia Horticulturae, 196, 15–27.
- Cakmak, I., Marschner, H. & Bangerth, F. (1989). Effect of zinc nutritional status on growth, protein metabolism and levels of indole-3-acetic acid and other phytohormones in bean (Phaseolus vulgaris L.). Journal of Experimental Botany, 40(3), 405–412.
- Broadley, M.R., White, P.J., Hammond, J.P., Zelko, I. & Lux, A. (2007). Zinc in plants. New Phytologist, 173(4), 677–702.
- Kaiser, B.N., Gridley, K.L., Ngaire Brady, J., Phillips, T. & Tyerman, S.D. (2005). The role of molybdenum in agricultural plant production. Annals of Botany, 96(5), 745–754.
Figures describe the published literature on seed treatments and humic substances at the rates used in those trials. They are not product-specific guarantees.
How to Use
How to use liquid seedling fertiliser: seed soak, seedling dip and root drench
Shake well before every use
This is a concentrated liquid with suspended mineral particles. Shake vigorously for 15–20 seconds before measuring. When diluting, add the fertiliser to a small amount of warm water (20–30°C) and stir for at least 30 seconds before topping up to the full volume. This ensures thorough mixing and uniform application.
When to use this product
This is a starter fertiliser, designed for the first 2–4 weeks of a plant's life. It is not a replacement for ongoing feeding. Once seedlings are established and growing strongly, transition to a Dr Forest crop-specific fertiliser (Tomato, Rose & Flower, All Purpose 4-4-4, etc.) for the vegetative and fruiting phases.
Application methods
Seed soak — before sowing
Submerge seeds in the diluted solution and leave for 6–12 hours. Drain and sow immediately — do not rinse. The humic and fulvic acids accelerate water imbibition through the seed coat while calcium and micronutrients are absorbed directly. Expect faster and more uniform emergence compared to untreated seed.
Seedling dip — at transplanting
Prepare the solution and dip seedling roots for 10–30 seconds before transplanting into the final position. This coats the root system with a nutrient-rich biostimulant film that promotes rapid re-establishment, reduces transplant shock, and feeds the root zone biology in the critical first days after planting.
Root drench — after planting
Apply immediately after sowing or transplanting. Pour the diluted solution directly over the planted area at a rate of 1 litre per square metre. This delivers calcium and micronutrients to the root zone where the emerging root tips will access them first. Follow with normal watering to settle the soil around seeds or transplants.
Step-by-step for seed soaking
- Shake the bottle vigorously. The suspension settles during storage — shake for 15–20 seconds before measuring.
- Measure 3–3.5 ml per litre of water. For a standard bowl or tray, 1 litre of solution is usually sufficient for a batch of seeds. Use warm water (20–30°C) for mixing.
- Add seeds and soak for 6–12 hours. Small seeds (lettuce, brassicas) need 6 hours. Larger seeds (peas, beans, sweetcorn) benefit from 10–12 hours. Do not exceed 12 hours.
- Drain and sow immediately. Do not rinse the seeds — the nutrient residue on the seed coat continues to feed the emerging root. Sow into moist compost or soil as normal.
- Optional: apply a root drench after sowing. Use the same dilution rate (3–3.5 ml/L) to water the tray or bed after sowing for maximum early nutrition.
A 500 ml bottle at 3 to 3.5 ml per litre makes about 143 to 167 litres of solution; the 1 litre bottle makes twice that. The method for applying fulvic acid as a seed soak on its own is covered in How to apply fulvic acid: rates and method.
Works well combined with…
Follow up with Seaweed Powder as a fortnightly biostimulant drench once seedlings are established. Use Amino Chelated Calcium for ongoing foliar calcium during fruiting. For soil-applied baseline nutrition, incorporate Yorkshire Polyhalite or Dr Forest crop-specific blends into the compost or soil before planting.
Storage
Store upright in a cool, dry place between 5–25°C, out of direct sunlight. Keep sealed. Shake vigorously before each use — the suspension settles during storage. Do not store diluted solution — mix fresh for each application. Keep out of reach of children.
Questions & Answers
Frequently asked questions about fertiliser for seedlings
A low-nitrogen feed that carries calcium, used dilute enough to touch seed and bare roots without harm. This one is built for that job: 4.13% calcium, iron, zinc, manganese and molybdenum, plus humic and fulvic acids, used at 3 to 3.5 ml per litre for soaking and drenching. A general-purpose liquid watered down to a seed-safe strength leaves its trace elements at background levels and still pushes leaf growth ahead of root growth.
At sowing. Soak the seed for 6 to 12 hours before it goes in, drench the tray at 3 to 3.5 ml per litre straight after sowing, or do both. The product is designed for the first 2 to 4 weeks; once the seedlings are established and growing strongly, move on to a Dr Forest crop-specific fertiliser for the rest of the season.
No. At the recommended dilution rates, this formulation is specifically designed to be safe for direct seed contact and young seedlings. The nutrient concentrations are set for the tiny quantities a germinating seed needs, well below the feeding levels used for established plants. Do not exceed the stated rates.
Small seeds (lettuce, brassicas, herbs): 6 hours. Medium seeds (tomatoes, peppers, flowers): 6–8 hours. Large seeds (peas, beans, sweetcorn, squash): 10–12 hours. Do not exceed 12 hours — prolonged soaking can reduce oxygen availability and impair germination. Drain and sow straight away; do not rinse.
The greatest improvements are typically seen in larger seeds with hard coats (peas, beans, sweetcorn, squash) and in crops that are sensitive to micronutrient shortfall from the start (brassicas, tomatoes, peppers, lettuce). Seed soaking is also particularly useful when sowing into cold or marginal conditions where germination is naturally slower.
Common causes are overwatering, cold compost, and the seed's own nitrogen running out before the roots can find more. This feed supplies iron, magnesium, manganese and molybdenum, which covers yellowing from a shortage of any of those, and a molybdenum shortfall in particular can look like a lack of nitrogen. It will not fix a waterlogged tray, and it is too low in nitrogen to fix a nitrogen shortage. For the tomato-specific version of the question, see Why are my tomato leaves turning yellow?.
No. It is a starter fertiliser for the germination and establishment phase, so the nutrient profile leans on calcium and micronutrients, with little of the N-P-K that sustained vegetative growth and fruiting need. Once seedlings are established, move on to a Dr Forest crop-specific fertiliser for the rest of the season.
All three carry calcium. This one is the seedling-stage product: it adds humic and fulvic acids and four trace elements, and is used at sowing and planting out. Cal-Mag is a pH-neutral calcium and magnesium powder for established plants through the season. Amino Chelated Calcium is a soluble foliar calcium for fruiting crops.
This product is non-toxic when used as directed. Avoid contact with eyes and skin, and wash hands after handling. Keep out of reach of children. Once diluted and applied, the area is safe for normal garden use.
It is made with organic ingredients; it is not certified. It is supplied in a recycled plastic bottle, and the bottle is recyclable. Made by hand in small batches in Stockport, Greater Manchester.
Before sowing, soak the seed at 3 to 3.5 ml per litre. Straight after sowing, drench the tray at the same rate. When you pot on or plant out, dip the roots at 10 ml per litre. It's low in nitrogen on purpose, because young plants need roots before leaves.
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