Is tomato feed good for all plants? Not lawns

By Joe Barrington, founder of Dr Forest · Published September 2026 · Updated 6 November 2026

No, tomato feed isn't good for all plants. It's a high-potash feed, usually with about twice as much potash as nitrogen, so it suits plants that are flowering or fruiting: tomatoes, chillies and peppers, cucumbers, courgettes, strawberries, and beans and roses in pots. In a kitchen garden, it covers the fruiting crops. Leafy salads do better on a balanced feed. Start once the first flowers or fruit show. Keep it off lawns, leafy salads, seedlings and acid-lovers such as blueberries, and give mixed beds a balanced feed.

For fruiting tomatoes my feed is Tomato Feed 3-4-6. For my own mixed pots and beds I use All Purpose 4-4-4. I formulate and blend both myself in Stockport. The rest of my feeds for fruiting crops are under tomato, chilli and pepper feeds. Crop-by-crop notes are in the plant growing directory.

Why tomato feed isn't good for all plants

Potassium (potash) supports flowering and fruiting, whereas a balanced feed has roughly equal nitrogen, phosphorus and potassium [1]. Tomorite, the liquid most UK gardeners mean by tomato feed, is 4-3-8: 4% nitrogen against 8% potash [2]. My 3-4-6 has the same two-to-one lean towards potash. The 4-4-4 is one to one, and a lawn feed leads with nitrogen. My guide to what's in Tomorite sets the two labels side by side.

So before you use tomato feed for other plants, ask what the plant is busy doing. Tomato feed helps a plant that's flowering or carrying fruit. Anything still growing leaf, roots or grass does better on a balanced all purpose feed or one higher in nitrogen.

Which plants like tomato feed

For tomatoes themselves, the RHS says to feed a high-potassium liquid every 10 to 14 days once the first fruits start to swell, and plants in pots need it most [3]. My guide to the best tomato feed covers which one to buy, and dry versus liquid.

Stick to the label rate. This is the catch with container gardening: in a pot or grow bag, extra feed builds up in the compost and can scorch the roots. If the lower leaves yellow while the plant is fruiting, check the watering and light before you double the feed: tomato leaves turning yellow has the full check. If you want a high-potash liquid that isn't a tomato feed, there's also a liquid potassium fertiliser, used at its label rate. For bedding and baskets, a bloom fertiliser is the other option, though more phosphorus doesn't mean more flowers.

Plant	Tomato feed?	How to use it
Tomatoes (pots, bags, greenhouse)	Yes, from first fruit set	Every 10 to 14 days once the first fruits swell [3].
Chillies and sweet peppers	Yes, once fruit is on	Tomorite's label halves the dose for peppers and aubergines: 10 ml in 4.5 litres, against 20 ml for tomatoes [2].
Cucumbers	Yes, once flowering	In pots or grow bags, a general liquid feed until they flower, then a high-potash feed such as tomato feed [4]. In a well manured or composted greenhouse border, feed lightly or not at all. In poor soil, feed every 10 to 14 days once the fruit starts to swell.
Courgettes and squash	In pots, once the first fruits swell	Every 10 to 14 days. In the ground they rarely need feeding unless the soil is poor [5] [6].
Strawberries	In pots, from the first flower buds	Fortnightly, with a general feed before the buds form [7]. In mulched ground they rarely need feeding.
Runner and French beans	In pots, once flowering	Fortnightly from the first flowers. In the ground they don't need feeding [8] [9].
Roses in pots	Yes, once flowering	Fortnightly from mid-spring to late summer, with a general feed until then [10]. Roses in borders get a rose or general feed in March or April and again after the first flush [10]: see organic rose fertiliser. Save feeding roses with tomato feed for plants in pots, once the first flowers show.
Sweet peas	A balanced feed while they climb, then tomato feed once flowering	Feed weekly or fortnightly with a liquid feed [11]. Switch to tomato feed when the first flower buds show, as potash supports flowering [1].
Patio pots in heavy bud, such as fuchsias and petunias	For a few weeks	Stop if leaf tips go brown, or older leaves yellow between the veins.

When tomato feed is the wrong choice

Too much potash crowds out magnesium. In a 2025 trial on tomato seedlings grown in a nutrient solution, tripling the potassium cut the magnesium the plants took up and left them 45% lighter [12]. Keep tomato feed for plants to the crops listed above, at the label rate.

Plant	Tomato feed?	Use instead
Lawns	No	A nitrogen fertiliser for lawns, because a lawn is grown for its leaf.
Leafy salads grown for their leaves	No	A balanced feed. Potash-heavy feed is a poor diet for leaf.
Blueberries, camellias and rhododendrons	No	In pots, a liquid feed made for ericaceous plants every two or three weeks, watered in with rainwater, as hard tap water slowly raises the pH of the compost [13].
Seedlings and young plugs	No	A gentle, dilute start. Save tomato feed until they flower.
Mixed pots and mixed borders	Not as the main feed	All Purpose 4-4-4 for the mix. Tomato feed only for pots or rows that are clearly in fruit.

Mixed gardens: use two feeds

If half the patio is tomatoes in fruit and the rest is bedding, herbs and a couple of shrubs, give each its own feed. A 2025 greenhouse trial in containers found one liquid organic feed was enough for lettuce, but concluded that fruiting crops such as tomato may need more than one to get the nutrient balance right [14].

To match a feed to each crop, read the NPK numbers on the bag or use the which fertiliser page. Organic and mineral tomato feeds are compared in organic vs chemical tomato fertiliser.

Common questions

Is tomato feed good for all plants?

No. It suits plants that are flowering or fruiting, such as tomatoes, peppers and chillies, strawberries, courgettes, roses in pots and flowering pots, but is a poor choice for lawns, leafy salads, acid-loving plants, seedlings and mixed borders.

Can I use tomato feed on flowering plants?

Yes, once they're in heavy bud or bloom, and the RHS suggests it for roses in pots once they flower. Stop if leaf tips turn brown or older leaves yellow between the veins.

What should I use instead for mixed pots and beds?

A balanced all-purpose fertiliser such as All Purpose 4-4-4. Keep tomato feed for the pots or rows that are clearly fruiting.

Is tomato feed the same as Tomorite?

Not quite: Tomorite is one brand of tomato feed, a 4-3-8 liquid, and the one many UK gardeners mean by the name. What's in Tomorite goes through its label in full.

Can I use tomato feed on roses?

Yes for roses in pots, fortnightly from mid-spring to late summer once they flower, as the RHS suggests. Roses in borders do better on a rose or general feed in March or April and again after the first flush.

Can you use tomato feed on hydrangeas?

Not as a regular feed: the RHS says established hydrangeas rarely need feeding, and too much fertiliser gives soft, leafy growth with fewer flower buds. On light, sandy soil a general feed in spring is enough, and blue ones grown in pots need ericaceous compost. [15]

Can I put tomato feed on my lawn?

No. Lawns need a feed that leads with nitrogen, and tomato feed is built for fruiting crops.

Is tomato feed high in nitrogen?

No, it's high in potash. Tomorite is NPK 4-3-8 and mine is 3-4-6, so both have about twice as much potash as nitrogen.

Sources

1. Royal Horticultural Society. Fertilisers: types and uses. rhs.org.uk/garden-jobs/fertilisers
2. Evergreen Garden Care UK Ltd. Levington Tomorite Concentrated Tomato Food, product page (NPK 4-3-8; 20 ml per 4.5 litres for tomatoes, 10 ml for peppers and aubergines). lovethegarden.com
3. Royal Horticultural Society. Tomatoes: grow your own. rhs.org.uk/vegetables/tomatoes/grow-your-own
4. Royal Horticultural Society. Cucumbers: grow your own. rhs.org.uk/vegetables/cucumbers/grow-your-own
5. Royal Horticultural Society. Courgettes: grow your own. rhs.org.uk/vegetables/courgettes/grow-your-own
6. Royal Horticultural Society. Squash: grow your own. rhs.org.uk/vegetables/squash/grow-your-own
7. Royal Horticultural Society. Strawberries: grow your own. rhs.org.uk/fruit/strawberries/grow-your-own
8. Royal Horticultural Society. Runner beans: grow your own. rhs.org.uk/vegetables/runner-beans/grow-your-own
9. Royal Horticultural Society. French beans: grow your own. rhs.org.uk/vegetables/french-beans/grow-your-own
10. Royal Horticultural Society. Roses: growing guide. rhs.org.uk/plants/roses/growing-guide
11. Royal Horticultural Society. Sweet peas (annuals): plant guide. rhs.org.uk/plants/lathyrus/sweet-peas
12. Chen, W., Hu, Z. and Liu, D. (2025). Compared to MgSO4, the Use of Magnesium Nanofertilizer Alleviates Potassium-Magnesium Antagonism in Tomato Roots. Agriculture 15(4): 368. doi.org/10.3390/agriculture15040368
13. Royal Horticultural Society. Blueberries: grow your own. rhs.org.uk/fruit/blueberries/grow-your-own
14. Chowdhury, M., Watson, O., Samarakoon, U.C., Altland, J.E. and Moine, J. (2025). Evaluation of Liquid Organic Fertilizers for Containerized Production under Controlled Environment. HortScience 60(5): 757 to 764. doi.org/10.21273/hortsci18466-25
15. Royal Horticultural Society. Shrubby hydrangeas: growing guide. rhs.org.uk/plants/hydrangea/shrubby/growing-guide