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Organic Tomato Feed 3-4-6 | Slow-Release Tomato Plant Food
A slow-release 3-4-6 feed for tomatoes.
from £11.50
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High-nitrogen fertiliser: 13% plant-based amino-acid nitrogen for strong, leafy growth
In short
Nitrogen fertiliser from Dr Forest is a 13% plant-based amino-acid feed, made from fermented plant sugars, for a high-N push without animal meals. It greens up leafy vegetables, brassicas and lawns quickly, then keeps feeding for around six weeks. High in sulphur, low in salt, and entirely plant-based.
13% Nitrogen Plant-Based High in Sulphur Low Chloride & Salt Fast + Slow Release
Nitrogen Extract is a high-nitrogen fertiliser supplying 13% nitrogen as amino acids and proteins — the form plants and soil microbes use to build leaves, stems and chlorophyll. It is made from fermented plant sugars (molasses), with the nitrogen-rich proteins drawn off and dried into a clean 3 mm granule (sometimes sold as nitrogen pellets). A natural, plant-based source of nitrogen, made in the UK.
Unlike fast synthetic salts such as ammonium nitrate, the nitrogen here is held in plant proteins. Roughly half is available within the first couple of weeks for a quick green-up, and the rest releases steadily over the following weeks as soil biology breaks the granule down. You get the speed of a feed and the staying power of an amendment, in one plant-based granule that is also high in sulphur and very low in chloride and salt.
13%Nitrogen (N)
~50%Released in 14 days
6+ weeksSustained feed
100%Plant-based
What a high-nitrogen plant food is used for in the garden
- Leafy vegetables and brassicas — lettuce, spinach, chard, cabbage, kale, sprouts and other crops grown for their foliage respond fast to available nitrogen, putting on bigger, deeper-green leaves
- Spring green-up and growth spurts — a targeted nitrogen boost for plants that have stalled, paled, or need to bulk up early in the season before they flower or fruit
- Lawns — a high-nitrogen lawn feed that drives strong green colour and dense growth; the slow-release tail keeps the lawn fed for weeks rather than a single flush and crash
- Hungry feeders mid-season — sweetcorn, courgettes, squash and similar crops that draw heavily on nitrogen during their main growth phase
- Correcting nitrogen deficiency — pale or yellowing lower leaves, slow growth and weak stems are classic nitrogen-hunger signs that this addresses directly
- Topping up the green stage of a feeding plan — use it for early leaf and stem building, then switch to a balanced or high-potash feed as plants move into flower and fruit
A plant-based nitrogen with the kick of a feed and the patience of an amendment.
How it compares
Nitrogen Extract (this product)
- 13% nitrogen and plant-based, from fermented plant sugars
- Amino-acid and protein nitrogen plus organic carbon and humic substances that feed soil life
- Fast start then a slow-release tail over several weeks
- High in sulphur, very low in chloride and salt — a low risk of salt build-up
- No strong smell, clean to handle and store
Synthetic nitrogen (ammonium nitrate, urea)
- A salt feed — fast, but prone to leaching and, with urea, loss to the air as ammonia
- Feeds the plant but not the soil; adds no carbon and no biology
- Higher salt index, so more risk of scorch and salt build-up if overdone
- Not permitted in organic growing
Plant-based and packed in recyclable, home-compostable paper.
The science of amino-acid nitrogen: why the form of nitrogen matters as much as the amount
Plants don't only eat nitrate
For most of the last century the textbook view was that plants take up nitrogen only as nitrate or ammonium — mineral forms — and that organic nitrogen has to be broken down by microbes into those minerals first. That view is now out of date. Plants take up intact amino acids and small peptides directly through their roots, and in many soils organic nitrogen is a significant part of what they actually use (Näsholm et al., 1998; Näsholm, Kielland & Ganeteg, 2009).
That is what this product supplies. The nitrogen here is held in amino acids and proteins, drawn from fermented plant material and concentrated into a granule. Some is taken up directly; the rest is mineralised by soil biology at a measured pace. The result is a feed that works with the soil rather than flooding it.
Why plant-based amino-acid nitrogen behaves differently
What's in the granule
- Nitrogen (13%) as amino acids and proteins — both directly available and microbially released
- Sulphur (as SO₃) — needed to build proteins and chlorophyll; nitrogen and sulphur work together, and a sulphur shortfall limits how well plants use nitrogen
- Organic carbon and humic substances — food and habitat for the soil microbes that cycle nutrients
- Trace elements and micronutrients carried through from the plant source material
- Very low chloride and salt — a low salt index, so little risk of osmotic stress or salt build-up
Why that matters in the soil
- Less waste: nitrate leaches readily and urea can gas off as ammonia; protein-bound nitrogen is held until biology releases it (Cameron, Di & Moir, 2013)
- Feeds biology, not just the plant: the carbon and humic fraction supports the microbes that drive nutrient cycling and build soil organic matter (Nardi et al., 2009; Ferro et al., 2022)
- Lower nitrate loading than synthetic nitrogen, with comparable growth when organic and mineral inputs are compared (Cardarelli et al., 2023)
- Sulphur in the same granule removes a common hidden limit on nitrogen use efficiency (Marschner, 2012)
Four mechanisms of action
01
Direct amino-acid uptake
Roots carry transporters for amino acids and short peptides and absorb them intact, short-cutting part of the soil nitrogen cycle. This is most useful in cooler soils and early in the season, when microbial mineralisation of nitrogen is slow and mineral nitrogen is scarce (Näsholm et al., 1998; 2009).
02
Dual-speed release
Around half of the nitrogen becomes available within roughly the first fortnight for a visible green-up, and the remainder releases gradually over several weeks as soil organisms digest the protein. One application feeds across a growth phase rather than spiking and crashing — and there is far less to leach away between feeds.
03
Nitrogen and sulphur together
Proteins and chlorophyll are built from both nitrogen and sulphur. When sulphur is short, plants cannot fully use the nitrogen they take up, and growth and leaf colour suffer. Supplying sulphur in the same feed keeps the two in step and improves how efficiently the nitrogen is used (Marschner, 2012).
04
Carbon for the soil, not just nitrogen for the plant
The organic carbon and humic substances in the granule feed the microbial community that releases nutrients, holds them against leaching, and builds stable organic matter. Studies that pair organic inputs with growing crops consistently show higher soil organic carbon and microbial activity than mineral-only feeding (Ferro et al., 2022; Liu et al., 2021).
Scientific references
- Näsholm, T. et al. (1998). Boreal forest plants take up organic nitrogen. Nature, 392, 914–916.
- Näsholm, T., Kielland, K. & Ganeteg, U. (2009). Uptake of organic nitrogen by plants. New Phytologist, 182, 31–48.
- Cameron, K.C., Di, H.J. & Moir, J.L. (2013). Nitrogen losses from the soil/plant system: a review. Annals of Applied Biology, 162, 145–173.
- Cardarelli, M. et al. (2023). Organic vs synthetic nitrogen and nitrate accumulation. Agronomy / Frontiers in Plant Science. [nitrate reduction with organic sources]
- Nardi, S. et al. (2009). Physiological effects of humic substances on higher plants. Soil Biology & Biochemistry, 41, 1296–1307.
- Ferro, N.D. et al. (2022). Organic and mineral fertilisation and soil organic carbon. Geoderma / Soil & Tillage Research.
- Liu, J. et al. (2021). Organic amendment effects on soil enzyme activity and yield. Applied Soil Ecology.
- Marschner, H. (2012). Mineral Nutrition of Higher Plants (3rd ed.). Academic Press. [nitrogen and sulphur nutrition]
How to use Nitrogen Extract: rates for beds, lawns, containers and leafy crops
A little goes a long way
This is a concentrated 13% nitrogen feed, so it is used at much lower rates than a balanced blend or a soil conditioner. Scatter the granules evenly, keep them off leaves and stems, and water in well. Apply to moist soil during active growth. Less, more often, beats one heavy dose.
How much, and how often
One application feeds for around six weeks: roughly half the nitrogen releases in the first fortnight, the rest over the following weeks. Because of that, do not reapply more often than every five to six weeks. Across all uses, a single dressing sits between 20 and 55 g per m² (a rounded handful is roughly 30–40 g). Match the rate to how hungry the crop is, using the guide below.
Base dressing — before sowing or planting
Scatter over the bed and rake or fork lightly into the top 5–10 cm a few days before sowing or planting leafy and hungry crops. Use the lower rate on already-fertile soil, the higher rate where growth has been weak or the bed is freshly dug.
Heavy nitrogen feeders — top dressing
The hungriest leafy crops: brassicas (cabbage, cauliflower, calabrese and broccoli, Brussels sprouts, kale), leeks, sweetcorn, courgettes, squash and pumpkins, rhubarb, and spinach and chard. Scatter around the plants, keep granules off the foliage, work in lightly and water in. Two to three feeds across the season is usually plenty; stop once growth is strong and well coloured.
Salad and moderate leafy crops — top dressing
Lettuce and salad leaves, beetroot and chard tops, leafy herbs, and any plant showing pale lower leaves or slow, stalled growth. Lighter, more frequent feeding suits fast salad crops better than one heavy dose.
Established lawns
Spread as evenly as you can on a still day and water in well. The fast fraction greens the lawn up, the slow tail keeps it fed for weeks. Avoid applying in drought or to dry turf, and stop feeding nitrogen by late summer so you are not pushing soft growth into autumn.
New lawns and overseeding
For a new lawn, work into the top 5 cm of the prepared seedbed before sowing or laying turf. For overseeding, scatter over the area after seeding and water in thoroughly. The slow release feeds through establishment without scorching young roots.
Fruiting crops — early stage only
Tomatoes, peppers, chillies, aubergines, beans and peas need nitrogen only to build their early leaf framework. Feed during vegetative growth, then stop at first flower and switch to a high-potash feed such as Bloom 2-8-10 or Late Bloom 0-5-10, or too much nitrogen pushes leaf at the expense of fruit.
Roses and flowering shrubs — spring nudge
A single spring application drives strong early foliage. Follow with a balanced or high-potash rose feed for the flowering flush, and avoid further nitrogen later in the season.
Pots and containers
Mix into the compost when potting up leafy plants, or lightly top-dress established pots and water in. Containers hold a small soil volume, so keep to the lower rate and do not over-feed.
Easy to overdo — don't
Even with a low salt index, too much nitrogen drives soft, sappy growth that flops, attracts aphids and resists flowering and fruiting; very heavy doses on dry soil can scorch. Stick to the rates above, water in, and reach for a balanced feed once leafy growth is established.
Step by step
- Measure. A level tablespoon is roughly 15–20 g. Weigh the first few applications until you have your eye in.
- Scatter evenly. Spread thinly across the area or around the base of plants. Keep granules off leaves, stems and crowns.
- Work in lightly where you can — a shallow rake or hoe on beds; for established plants and lawns, leave on the surface.
- Water in well. Moisture starts the release and moves the first nitrogen down to the roots. If no rain is forecast within 48 hours, water the area to help the granules break down and prevent scorch.
- Repeat on schedule — no more often than every five to six weeks — through the growing season, then taper off as plants move into flower and fruit. On light, sandy soils, split feeds and keep to the lower rates. Store sealed, cool and dry.
Works well combined with…
Pair with Seaweed Meal for the trace elements and biostimulant compounds a straight nitrogen feed doesn't carry. Move to Bloom 2-8-10 or Late Bloom 0-5-10 once crops set flower and fruit. For an all-round leafy-stage feed, use alongside Veg 4-4-4. On lawns, follow with Volcanic Rock Dust to remineralise the soil beneath the turf.
In the Dr Forest living-soil programme
Within the Dr Forest living-soil programme, this is the mid-flower nitrogen booster for the Max yield build — about 0.6 g per litre of soil in total, split across two mid-flower doses. It is the lever that adds weight while potash and magnesium stay below their ceilings. See the Living Soil Kit and Refills.
Frequently asked questions about Nitrogen Extract
Yes. It is a plant-based nitrogen feed of amino-acid and protein nitrogen from fermented plant sugars (molasses), not a synthetic ammonium-nitrate or urea salt. The granule also carries organic carbon and humic substances that feed the soil life which releases the nitrogen.
Nitrogen held as amino acids and proteins rather than as a mineral salt. Plants can take up some of it directly; soil microbes release the rest steadily. In the garden it is a high-nitrogen (13% N) feed for leafy growth, spring green-up, lawn colour, and correcting nitrogen hunger, with a slow-release tail that continues for around six weeks (roughly half available in about a fortnight).
At 13% nitrogen it is one of the higher-nitrogen organic feeds in the range, without the leach-and-spike behaviour of synthetic salts. Best for the leaf-and-stem stage: leafy greens, brassicas, sweetcorn, lawns, and plants showing nitrogen hunger. Ease off once buds and fruit set — switch toward a balanced or potash-led feed so you do not push leaf at the expense of flowers and fruit.
This is a concentrated 13% N feed — lower rates than a balanced blend. Typical single dressing: about 20–55 g per m² (a rounded handful ≈ 30–40 g). Bed prep: 30–50 g per m² once. Heavy nitrogen feeders (top dress): 40–55 g per m² every 5–6 weeks in active growth. Leafy crops: 25–40 g per m² every 5–6 weeks. Lawns: 25–40 g per m², spring to mid-summer, once or twice 6–8 weeks apart. Pots: 2–4 g per litre of compost. Water in; keep granules off foliage and crowns. Prefer the pack in hand.
Roughly half the nitrogen is available within about a fortnight, so leafy green-up is often visible in one to two weeks in active conditions. The rest releases over the following weeks — one dressing keeps feeding rather than spiking and vanishing.
Low salt index versus synthetic nitrogen, but it is still 13% N. Over-application drives soft, sappy growth, aphids, and poor flowering/fruiting; heavy doses on dry soil can scorch. Stick to the rate band, water in, and do not reapply early because “nothing happened” in the first few days.
Classic signs: pale or yellowing older leaves first, slow growth, thin weak stems (nitrogen is mobile in the plant). A 13% amino-acid nitrogen dressing addresses that hunger: quick green-up from the fast half, sustained feed from the slow half. Also check watering, compaction and cold soil before blaming feed alone.
Urea is the agronomy “king” nickname for concentrated synthetic N (~46% N) — not an organic garden badge. Synthetic N is a fast salt: quick, leachy, and adds little to soil life. This product holds nitrogen in protein/amino-acid form until biology releases it, adds organic carbon and humic substances. Use it when you want leafy drive without a salt spike; use a balanced bag (All Purpose 4-4-4) when the whole NPK job matters.
Yes. It is suitable for vegan gardening. The nitrogen is plant-based, from fermented molasses, with no animal meals. Low odour compared with many animal-meal fertilisers.
Plant-based, low salt, no strong smell to attract animals. Still: store sealed, keep children and pets off treated areas until watered in, wash hands after handling.
Yes, on edibles, ornamentals and lawns. It shines on leafy and hungry crops and during early, leafy growth. Go easy on flowering and fruiting plants once they have set buds — too much nitrogen then pushes leaves at the expense of flowers and fruit, so switch to a balanced or high-potash feed at that stage.
The nitrogen is plant-based, extracted from fermented plant sugars (molasses) and dried into a clean granule. Keep it sealed in a cool, dry place; the granule is low in salt and stores well. Packed in recyclable, home-compostable paper.
During leafy growth, mostly spring to midsummer. Rake 30–50 g per m² into beds a few days before sowing or planting. Top-dress brassicas, leeks, sweetcorn and other hungry crops at 40–55 g per m² every 5–6 weeks, and salads at 25–40 g. Feed lawns at 25–40 g per m² once or twice from spring to midsummer, 6–8 weeks apart, and stop by late summer. Give tomatoes, peppers, beans and peas 20–30 g per m² once or twice before flowering only.
For this season's crops, use a concentrated plant-based feed like this one: 30–50 g per m² raked in a few days before planting, then 25–55 g per m² every 5–6 weeks for hungry leafy crops. Roughly half of it is available in about a fortnight and the rest follows over the next few weeks. For the long term, grow peas and beans, which fix their own nitrogen, and keep adding compost so soil life has something to work with. This product is vegan; the nitrogen comes from fermented molasses.
No. Epsom salt is magnesium sulphate, so it supplies magnesium and sulphur but no nitrogen. Pale, yellowing older leaves can come from either a nitrogen or a magnesium shortage. With nitrogen, the whole leaf pales evenly. With magnesium, the yellow sits between green veins. For nitrogen, use a nitrogen feed such as this one at 13% N.
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