Is tomato feed good for all plants?

By Joe, Founder of Dr Forest · Sep 2026 · Edited 24 Sep 2026 · 6 min read

High-potash tomato feed is a job, not a universal tonic. Use it where fruit or bloom asks for potash; leave the mixed garden on a balanced bag.

Short answer: no. Tomato feed suits fruiting tomatoes, chillies and some flowering plants once they are working hard. It is a poor default for lawns, leafy salads as the main crop, ericaceous shrubs, and most seedlings. For fruiting tomatoes I reach for organic tomato fertiliser; for mixed pots and beds I stay on All Purpose.

Garden centres still sell "tomato feed" as if it were a general plant tonic. That habit comes from liquid high-potash bottles that have sat on UK shelves for decades. The chemistry is fine for the right job. The mistake is pouring it on everything that looks a bit tired.

What tomato feed usually is

Most tomato feeds are higher in potassium (potash) relative to nitrogen. The idea is simple: once fruit is setting, you want fill and flavour more than endless soft leaf. Our Organic Tomato Fertiliser is a 3-4-6 blend made with organic ingredients and hand-blended in Stockport. Liquids in the same aisle often follow a similar high-K pattern; Tomorite is the familiar example many UK gardeners mean when they say "tomato feed".

That soft mention is only for orientation. This post is not a brand fight. If you want a full comparison, the existing Tomorite vs Dr Forest guide already owns that SERP. Here the question is narrower: which plants should see a high-potash tomato feed at all?

High potash is not magic. It does not fix dry compost, cold nights, or a plant that never flowered. It supports fruiting and some flowering once the crop's job has changed. Before that, a balanced feed is usually calmer.

When tomato feed is a good fit

Use it when the plant is clearly in a fruiting or heavy-bloom phase and you want potash without pushing soft leafy growth. Cordons and bush tomatoes after first fruit set are the textbook case. Chillies and sweet peppers follow the same logic once fruit is on the plant. Some flowering patio plants that are packing buds can also take a high-K rhythm for a stretch of the season.

Keep rates modest. A pot or growbag has nowhere for surplus salts to go. Light top-dress watered in, or a dilute liquid if you prefer, beats a heavy dump every time the plant looks sulky. If lower leaves yellow while fruit is setting, check water and light before you double the feed.

Working "yes" list for UK gardens. Fruiting and some flowering jobs earn tomato feed; mixed planting usually does not.

When tomato feed is the wrong bag

Lawns want a turf programme, not a fruiting fertiliser. Leafy salads grown for leaves want steady nitrogen more than a potash spike. Blueberries, camellias and other ericaceous plants need acid-leaning nutrition and the right soil chemistry; pouring tomato feed on them because "it is plant food" is wishful thinking. Most seedlings want a dilute, gentle start, not a high-K fruiting mix.

Mixed borders and mixed patio pots with shrubs, perennials, leafy starts and the odd annual side by side belong on a balanced bag. That is where organic all purpose fertiliser earns its keep: even growth across varied planting, without forcing one neighbour into a fruiting diet.

"No" list for PAA trust. Saying no here is how the right bag ends up on the right plant.

Tomato feed is a fruiting tool. Treat it like a specialist spanner, not the only wrench in the shed.

Mixed gardens: two doors, not one tonic

If half the patio is tomatoes in fruit and the rest is mixed bedding, herbs and a couple of shrubs, do not force one bottle onto both jobs. Keep Tomato 3-4-6 on the fruiting pots. Put All Purpose 4-4-4 on the mixed containers and beds. That split is dull on purpose. It matches what each plant is actually doing in September as nights cool and fruit still wants fill.

For a calm routing map by crop and site, use the shop page on which fertiliser. It exists so you do not have to guess from the loudest aisle label. Series posts on all-purpose versus specialist fertiliser cover the decision in more depth once you are comparing bags rather than diagnosing a single crop.

Related: Organic Tomato Fertiliser, 3-4-6 · Organic All Purpose Fertiliser, 4-4-4 · which fertiliser · organic rose fertiliser

Is tomato feed good for all plants? No, and that is the useful answer. Save high-potash feed for fruiting tomatoes and a few clear cousins; leave lawns, leafy salads, ericaceous shrubs and mixed planting on the systems that fit them. One specialist bag used in the right month beats a tonic poured on everything that looks tired.