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Citrus fertiliser UK: feed a potted lemon all year

Updated: October 2026

The lemon comes indoors in autumn, and stopping until spring is tempting. For citrus fertiliser in the UK, that pause fights the Royal Horticultural Society. Container citrus stay on feed all year. The formula changes: a high-nitrogen summer feed, then a more balanced winter feed. A bottle that only says Mediterranean is not automatically both. This page is that switch, for a lemon, orange or similar plant in a pot, greenhouse or conservatory. The [Mediterranean plant food comparison](/hub/fertiliser-soil-and-bark-mulch/mediterranean-plant-food) holds the four listings if you still need a pack. The RHS grow-citrus page and the amazon.co.uk listings were used. There was no lab test. A qualifying purchase through our links can earn us a commission at no extra cost to you.

The lemon comes indoors in autumn, and stopping until spring is tempting. For citrus fertiliser in the UK, that pause fights the Royal Horticultural Society. Container citrus stay on feed all year.

Our top picks

Substral Substral Naturen citrus and Mediterranean liquid, 500 ml

Best overall

Substral Substral Naturen citrus and Mediterranean liquid, 500 ml
3.9/10about £15.88
View offer
Algoflash Algoflash Alimed Mediterranean plant fertiliser, 750 ml

Best value

Algoflash Algoflash Alimed Mediterranean plant fertiliser, 750 ml
3.3/10about £17.79
View offer
Substral Substral Naturen long-term citrus and Mediterranean, 1.2 kg

Rank 3

Substral Substral Naturen long-term citrus and Mediterranean, 1.2 kg
4.9/10about £19.19
View offer
On this page
  1. 1.Why a UK lemon is still fed in winter
  2. 2.Summer feed, then winter feed
  3. 3.What the compared bottles say about citrus
  4. 4.Water the pot before you strengthen the mix
  5. 5.Questions about winter feed

Why a UK lemon is still fed in winter

Citrus in UK pots spend summer outdoors and winter under cover, so the RHS grow-citrus page keeps the feed going. Stopping in November, including the line at Clifton Nurseries, conflicts with that page. Follow the RHS calendar. A centrally heated room is a poor long-term home. Night examples include some lemons down to 5°C, kumquats often at 7°C or more, limes and grapefruits above 10°C, and calamondin at least 13°C.

Summer feed, then winter feed

From late March to October, use a high-nitrogen summer citrus feed. From November to mid-March, use a more balanced winter citrus feed. Vitax sells that change as two tubs, both quoted at 5 g in 2.5 litres. That rate stays on the Vitax label. Citrus Focus, £8.95 for 1 litre on 21 October 2026, prints 10 ml per litre weekly and limits regular use to March until October. It is not a named winter formula. Its 10 ml stays on its label.
Substral Substral Naturen citrus and Mediterranean liquid, 500 ml

Testsieger

Substral Substral Naturen citrus and Mediterranean liquid, 500 ml
3.9/10about £15.88
View offer

What the compared bottles say about citrus

The 500 ml Substral liquid at £15.88 says citrus and Mediterranean plants, and prints a mixing ratio of 1:0. The 1.2 kg pack at £19.19 names lemon, orange and mandarin, claims up to three months, and the item-form field says Paste. That claim is not a winter feed unless the pack says so. Algoflash, 750 ml at £17.79, has no winter line and no dose. Cultivers, 20 kg at £56.28, prints NPK 8-1-5 for olive and Mediterranean plants. None of those listings states an iron analysis or a summer-and-winter pair. Pack size is on the Mediterranean plant fertiliser buying guide. Olive timing is on how to feed Mediterranean plants.

Water the pot before you strengthen the mix

Let the surface dry, then water with tepid rainwater, and let the excess drain. Never leave the pot standing in water. A dry surface is not a reason to double the dose, and a wet saucer is not a reason to add a stronger capful. If you only have tap water, still follow the label rate. These four products state no iron figure.

Questions about winter feed

If the label has no winter sentence, keep the bottle for the growing season and buy a winter citrus feed that names the months and the rate. Citrus Focus at £8.95 answers a weekly growing-season dose. It does not close the November gap. When drainage, light and frost cover are already right and the tree still fails, another bottle is the wrong next step.

Common questions

Do citrus in UK pots need feed in winter?
Yes, on the RHS grow-citrus page. They move from a high-nitrogen summer feed to a more balanced winter feed from November to mid-March. The pot should still drain, and winter watering should wait until the surface has dried. A nursery that tells you to stop is a conflicting line. Your bottle counts as the winter feed only when its label says so.
What is the difference between summer and winter citrus feed?
The summer feed is the high-nitrogen one, from late March to October. The winter feed is the more balanced one, from November to mid-March. Shops often sell them as two tubs. Vitax is quoted at 5 g in 2.5 litres, weekly in summer and monthly in winter. Those rates stay on the Vitax label. A Mediterranean liquid with one unnamed formula has not stated this difference.
Is a Mediterranean plant food automatically both?
It is both only if the label gives a summer instruction and a winter instruction. The four listings name citrus to different degrees, and none of the listings states that pair or an iron analysis. The 1.2 kg claim of up to three months is a duration, not a winter formula. Use a combined bottle inside the season it describes, and add a winter product when the label is silent.
How should I water a lemon that has come indoors?
Let the surface dry, then water with tepid rainwater so the excess runs out. Empty the saucer. The pot should not stand in water. Keep the winter feed for when the compost is ready to water, at the rate on a winter label. A warm living room is a poor long-term spot. A cool, bright porch or conservatory fits the RHS winter place more closely, within the temperature examples for your type of citrus.
Which of these packs name lemon or citrus?
The 500 ml Substral title says citrus and Mediterranean plants. The 1.2 kg bullets name lemon, orange and mandarin as well as oleander, hibiscus, olive and fig. Algoflash says Mediterranean plants, and the target field says Plants. Cultivers says olive and Mediterranean plants on a 20 kg agricultural sack. Naming citrus is not the same as printing a winter dose. None of the four prints the summer-and-winter pair.
Can I copy 10 ml per litre onto my bottle?
That figure is Citrus Focus, on the page fetched on 21 October 2026. Vitax is quoted at 5 g in 2.5 litres. Substral's 500 ml listing prints 1:0. Algoflash prints no dilution. The 1.2 kg and 20 kg packs print no gram rate for one pot. Use the number on the pack you own. Leave the other numbers on their own labels.

Related pages

Yellow leaves on a lemon tree

Mediterranean plant food

Best Mediterranean plant food for a small UK patio

Mediterranean plant fertiliser: checks before you buy

How to feed Mediterranean plants across the UK year

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 21 October 2026. A star line is not a count of UK reviews. Organic wording is quoted from the listing, and no UK organic body is named. Oleander toxicity is the Royal Horticultural Society plant note, not a result of feeding.

  1. RHS, How to grow citrus (retrieved 21 October 2026)
  2. RHS, How to grow olives (retrieved 21 October 2026)
  3. RHS, Citrus problems (retrieved 21 October 2026)
  4. RHS, Nutrient deficiencies (retrieved 21 October 2026)
  5. RHS, How to feed plants (retrieved 21 October 2026)
  6. GOV.UK, Manufacturing and marketing fertilisers (retrieved 21 October 2026)
  7. Fertilising Products Regulations 2020 (retrieved 21 October 2026)
  8. RHS, Oleander (Nerium oleander) (retrieved 21 October 2026)