Plant feeds, step by step
Interactive lesson: nettle and comfrey feed, dilutions, wood ash and human urine, with hygiene rules and the interval before harvest.
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The whole lesson as text
1. When a liquid feed is needed
Liquid feeds are a top-up, not a replacement for compost and manure.
- Hungry crops — Tomatoes, peppers, aubergines, cucumbers, squash, cabbages, leeks and celery need feeding in July and August. So do seedlings and pots, where there is little soil.
- Yellow lower leaves — The lower leaves turn pale and yellow and growth stops: lack of nitrogen. Feed with nettle or urine, diluted.
- Brown leaf edges — Brown edges on older leaves and small, poorly coloured fruit mean lack of potash. Feed with comfrey and a little ash.
- Moist soil, then feed — Water with plain water first, then with the feed, in the morning or evening. Never on dry soil at midday: that way it doesn't burn the roots and nothing evaporates.
Why: If a bed got enough compost or well-rotted manure in spring, most vegetables need no extra feeding. Liquid feeds are for hungry crops with a long season that have used up what was in the soil by July and August.
- If the same sign keeps coming back for years, get a soil test first.
- Blossom end rot on tomatoes and peppers comes from uneven watering: mulch and even watering help.
2. Nettle feed
The stinging nettle is the best free source of fast nitrogen, and it grows along fences, barns and compost heaps.
- Cut before flowering — Gloves and long sleeves. Cut the top 30–50 cm, no roots and no seed: nettles in seed (July–August) spread through the garden.
- Not a metal container — A plastic barrel or water butt, a wooden tub or a stoneware pot. Not a metal container: the feed reacts with iron.
- 1 kg to 10 L — 1 kg of fresh nettles (or 150–200 g dried) to 10 L of water, ideally rainwater. Chop the nettles.
- Stir and cover — Stir once a day and cover with mesh or a grid. At 20 °C it is ready in 10–14 days, when it stops foaming and turns dark.
Why: Cut it before flowering, in April–June. After cutting it regrows, giving a second and third cut until September.
- The feed stinks badly and draws flies: keep the barrel well away from the house and the neighbours, covered, and never uphill of a well.
- Cold soak, when you need it straight away: 1 kg of nettles in 10 L of cold water for 12–24 hours, strain and dilute 1 : 5. It doesn't smell, but it has fewer nutrients.
3. Straining and diluting · Locked
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4. Comfrey: potash for fruit · Locked
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5. Wood ash · Locked
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6. Human urine · Locked
Buy the Plant feeds module and you get the PDF to download and print, plus lifetime access to this interactive lesson: all 6 chapters, 24 steps.