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Tomato Feed Calculator — Feeding Schedules & Quantities
Calculate tomato feed dilution rates and feeding schedules.
Plants you'll feed on the same schedule — a 4.5 L can of diluted Tomorite waters roughly 2 plants.
Concentrates dilute in water; ready-to-use is applied neat; soluble/granular feed (e.g. Chempak) is sold by weight.
UK season is about 14 weeks (June-September), starting once the first truss sets.
Allow roughly 1 L of diluted feed per plant per feed; large plants in growbags may take more.
Price of one bottle or tub — used to estimate total feed cost for the season.
Weekly is standard; raise to 2-3 at the 2nd/3rd truss stage when fruit is swelling fast.
Tomorite is 4.4 mL/L (20 mL per 4.5 L). Most high-potash concentrates sit in the 4-5 mL/L range.
Soluble feed rate per litre of water — Chempak is about 1 g/L (1 tsp ≈ 5 g per 5 L).
Concentrate bottle volume — UK feeds are typically 500 mL or 1 L.
Weight of one tub of soluble/granular feed (Chempak tubs are 750 g).
How We Calculate This
Total feeds = feeding weeks × feeds per week. Total water = number of plants × litres per plant × total feeds.
For a liquid concentrate, feed needed = total water × dilution rate. Tomorite's label rate is 20 mL per 4.5 L, i.e. about 4.4 mL per litre — not 10 mL/L. For ready-to-use feed the volume equals the water applied (it is used neat). For soluble/granular feed, grams = total water × the g-per-litre rate.
Packs needed = feed required ÷ pack size. Liquid concentrates are sold in 500 mL or 1 L bottles; soluble/granular feeds (e.g. Chempak) come in tubs sold by weight.
Frequently Asked Questions
Begin once the first truss of fruit has set, typically in June. Feed weekly outdoors (every 7-14 days), or at alternate waterings under glass where growth is faster. Do not feed before fruit sets — early feeding just pushes leafy growth.
Levington Tomorite is diluted at 20 mL (one capful) per 4.5 litres of water — about 4.4 mL per litre. A 1 litre bottle makes roughly 225 litres of ready-to-use feed.
Yes. Overfeeding causes lush foliage at the expense of fruit, and the resulting growth surge can trigger blossom end rot. Stick to the label dilution rate rather than making it stronger.
A high-potash feed encourages fruiting and flowering. Tomorite is NPK 4-3-8 (plus magnesium and seaweed). General-purpose feeds carry too much nitrogen, which favours foliage over fruit.
Yes. Any fruiting or flowering plant benefits from high-potash feed, including peppers, aubergines, cucumbers, strawberries, and flowering hanging baskets.
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.