Best liquid plant feeds

Liquid feeds are fertilisers that are applied as you water your plants. They include both concentrated liquids you dilute in water and granules you dissolve. You can use them for pots and borders to give your plants an instant pick-me-up. If you prefer to add controlled-release fertiliser to your pots, you may still use a liquid feed at the end of the summer as the controlled-release fertiliser runs out.

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Best liquid plant feeds

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Getting the best from liquid feeds

Liquid fertilisers are most commonly used to feed pots of bedding plants, but can also be used on many ornamental plants and veg. Some of them are also suitable to be used on seedlings. In our trials (Feb 23 and Feb 24) we found that applying the recommended low dose to seedlings once the first leaves appear can boost growth. It’s best to use a balanced feed or one with very high nitrogen content, rather than a high-potassium feed. Miracle Gro All Purpose Concentrated Liquid Plant Food gave us good growth. 

Liquid feeds can be used all through the growing season. They work by giving plants a regular boost of essential macronutrients (that’s nitrogen, phosphorus and potassium) and micronutrients. The feed is easily taken up by plants and you can increase or decrease the dose or the regularity of feeding, depending on how quickly your plants are growing and flowering. You’ll find guidelines on the pack to help you decide on a feeding regime. 

You need to remember to use them regularly. If you’re apt to forget, you might prefer to use one that you apply every watering, such as Phostrogen All Purpose Plant Food. Alternatively, you may prefer to use a controlled-release feed (CRF), and only use a liquid feed as a supplement towards the end of the season when the CRF starts to run out. 

As with all feeds and garden chemicals, store them in a cool, dry place out of direct sunlight, such as a shed or garage. Use them up as soon as you can and buy fresh as and when you need it.

How we test liquid feeds

In spring 2023 we chose 16 widely available liquid feeds, alongside some products that are new to the market. We grew pelargoniums from plug plants, potting three plants to a 10L pot and growing three pots for each feed. 

We grew pelargoniums as they're hungry plants – both leaf colour and the number of blooms is affected by the quality of the feed. 

We potted up our plants in early June and began to feed in early July. We fed according to the dose and frequency rate suggested on the packaging. This varied from every watering to once every two weeks. 

Every week we assessed the plants for size, leaf colour, health and flowering, and removed spent flower stalks, recording the number. At the end of the trial, we cut the plants at the base and weighed them.