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How to use herb fertiliser on pots and balcony boxes

Updated: October 2026

You have a bottle or a pack of sticks and a pot of herbs, and the job is to use herb fertiliser without pouring concentrate onto dry compost or pushing sticks into a mix that already feeds itself. This sequence is for a UK pot or balcony box in the growing season. It is from Peter F., the DIY and tools editor, on 20 October 2026, using the doses on the four amazon.co.uk listings in the [herb fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/herb-fertiliser). A qualifying purchase can earn a commission at no extra cost to you. Basil, parsley, mint and chives have their own limits on [fertiliser for basil](/hub/fertiliser-soil-and-bark-mulch/herb-fertiliser/sub/herb-fertiliser-for-basil).

You have a bottle or a pack of sticks and a pot of herbs, and the job is to use herb fertiliser without pouring concentrate onto dry compost or pushing sticks into a mix that already feeds itself.

Our top picks

Baby Bio Baby Bio Herb Food, pack of 2

Best overall

Baby Bio Baby Bio Herb Food, pack of 2
3.5/10about £5.98
View offer
Baby Bio Baby Bio Herb Food, 2 x 175 ml

Rank 2

Baby Bio Baby Bio Herb Food, 2 x 175 ml
6.9/10about £10.50
View offer
Substral Substral Naturen herb sticks, 30

Alternative

Substral Substral Naturen herb sticks, 30
6.2/10about £12.40
View offer
On this page
  1. 1.Before you open the bottle
  2. 2.Liquid herb food
  3. 3.Fertiliser sticks
  4. 4.When to stop

Before you open the bottle

The compost should be moist, not dust-dry and not sitting in a saucer. BBC Gardeners' World says not to feed a wilted plant. Water first, wait until it stands up, then mix a feed. A plant that flops at noon and firms up by evening was short of water or too hot, not short of fertiliser. The RHS says container feeding usually starts about six weeks after planting, and that you should not fertilise after September. A herb potted on Saturday into a bag that feeds for months does not need a stick or a full-strength liquid tonight. The about £5.98 Baby Bio listing states a fortnight and prints 1:X. The about £10.50 listing states drops and a cap and does not state the interval. Do not stitch them into one instruction. Woody herbs stay at or below the label.

Liquid herb food

For Baby Bio Herb Food, 2 x 175 ml, the listing says 5–10 drops to 0.5 litre, or half a capful to 1 litre, poured onto the compost. This listing has no fortnight. Start at 5 drops in half a litre for a small pot. The about £5.98 pack says mix into usual watering every two weeks, and its ratio is 1:X, so this page cannot give you a drop count for that bottle. Do not copy the dearer listing's capful and call it the same product. That cheaper title says spray, while the bullets say mix into watering. Do not mist neat concentrate onto leaves. Neudorff's 250 ml listing states no dose and no interval.
Baby Bio Baby Bio Herb Food, pack of 2

Testsieger

Baby Bio Baby Bio Herb Food, pack of 2
3.5/10about £5.98
View offer

Fertiliser sticks

Substral's 30 sticks say 1–5 depending on pot size, or 2 per plant in a balcony box, repeated every two months, lasting up to two months. A 9 cm pot is the low end of 1–5. Two plants in a trough are four sticks on the two-per-plant line, not two for the box. Push them near the rim rather than against the stem, then water. Do not add a liquid in the same weeks unless the label says so. The bullets name basil, parsley, indoor plants and balcony boxes, not an open bed. The saved reviews are Reviewed in Germany, and two say no growth was visible. That is not a UK result and not a reason to double the count. If you are still choosing the form, that fork is on liquid herb feed or fertiliser sticks.

When to stop

Stop after September unless you are keeping a tender herb indoors and the label allows a lighter clock. The RHS states that cut-off. Stop if the plant wilts after a dose. Flush with plain water until it runs from the drainage holes, and do not feed again until growth looks normal. One UK review on the about £10.50 listing says potted basil died and sage wilted after use as directed. Stay inside the printed range. If leaves are large, pale and almost scentless, lengthen the gap. Call NHS 111 if someone swallows the product or gets it in an eye. Call a vet if a pet eats sticks or drinks concentrate.

Common questions

How often should I feed herbs in a pot?
After about six weeks, and not after September, on the RHS clock. In the growing months, many UK guides use every two or three weeks as a rule of thumb for a liquid. Follow that only if your bottle agrees. Do not merge the about £5.98 fortnight with the about £10.50 drop count.
What if the listing has no dose?
Do not invent one from another listing. Neudorff's listing has no millilitres per litre. The cheaper Baby Bio listing prints 1:X. Wait until the pack gives a cap, a drop count or a stick count. A guessed rate is how a small pot gets a double supply, especially on compost that already contains a starter charge.
Can I spray Baby Bio because the title says spray?
No. On the about £5.98 listing the title says spray and the bullets say mix into watering. Use the diluted mix on the compost. Do not put neat concentrate on the leaves. If the bottle in your hand has a separate foliar dilution, follow that printed line, not the word spray alone.
Should I feed in winter on a UK windowsill?
Usually no. The RHS says not to fertilise after September. A resting herb in weak December light does not use a summer dose. If the label allows a reduced winter feed for a tender basil indoors, keep it lighter than the May rate. If the label is silent, use water and light.
What if the plant is wilting?
Water with plain water and do not feed while it is limp. If it wilted after a feed, flush the pot until water runs from the base, then wait for steady growth. Do not correct the wilt with a stronger mix. Check drainage, because sodden compost and drought can look alike by evening.
Do I wash the leaves before I cook?
Yes, as ordinary kitchen practice. None of these four listings prints a wash-before-use line. Vitax, which is not one of the four, prints a wash line on its own feed. Washing is not an organic-food certificate, and it does not fix an overdose.

Related pages

Herb fertiliser buying guide

Herb fertiliser

Best herb fertiliser if you will measure a drop dose

Fertiliser for basil on UK windowsills and in pots

Liquid herb feed or fertiliser sticks for herb pots

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the four amazon.co.uk listings captured on 20 October 2026. An organic-farming line is not an organic-food certificate. Texts marked Reviewed in Germany are not UK reviews. This is not a laboratory test or a taste test.

  1. RHS, Growing herbs in containers (retrieved 20 October 2026)
  2. RHS, How to feed plants (retrieved 20 October 2026)
  3. RHS, Mediterranean herbs in a pot (retrieved 20 October 2026)
  4. GOV.UK, Manufacturing and marketing fertilisers (retrieved 20 October 2026)
  5. The Fertilisers Regulations 1991 (retrieved 20 October 2026)
  6. GOV.UK, Organic food labelling (retrieved 20 October 2026)
  7. Plantura, Feeding herbs (retrieved 20 October 2026)
  8. BBC Gardeners' World, feeding pots (retrieved 20 October 2026)