Liquid feed or slow-release granules — which should I use?

The choice is really about control against convenience. Granules release nutrients gradually in response to moisture and temperature, so they meter themselves and you cannot easily intervene. Liquid feed goes in and is available immediately, which means you can respond to what the plant is doing but also means it is gone within a week or two.

Safety

Step by step

1. Use granules where consistency matters more than control.Containers, hanging baskets, shrubs in pots and anything you will not be there to feed weekly. Mixed into the compost at planting, controlled-release granules typically cover three to six months depending on the product.
2. Use liquid feed where you want to change what you are giving.A balanced or nitrogen-rich feed for leafy growth in early summer, switching to a high-potash one for flowers and fruit. Liquid lets you make that switch on a given week; granules do not.
3. Understand how granules release.Coated controlled-release granules release faster when it is warm and wet and slower when it is cold and dry — which broadly matches what the plant needs. Uncoated slow-release organic feeds such as bone meal or seaweed meal break down through soil biology, which is slower and less predictable.
4. Understand what happens to liquid feed.It is available immediately and it leaches. In a container, a few heavy waterings will flush most of it out. This is why weekly is the standard interval rather than monthly.
5. Use both in containers.Granules at planting to cover the first few months, then weekly liquid feed once they are exhausted. This is what commercial growers do, and it is what keeps baskets flowering into September.
6. Feed at the label rate, weekly, rather than heavily and occasionally.Excess soluble fertiliser scorches roots and accumulates as salts on the compost surface. A weak solution often is better than a strong one rarely, in every respect.
7. Match the analysis to the job.Higher nitrogen for leaves and green growth, higher potassium for flowers and fruit, higher phosphorus for roots and establishment. The label carries the analysis and the rate — read it rather than assuming, because the same brand sells several different formulations.
8. Do not feed a plant that is struggling for another reason.A plant short of water, sitting in waterlogged compost, or with damaged roots cannot use fertiliser and will be harmed by concentrated salts around injured roots. Fix the water first and feed when it is growing.
9. Do not feed anything dormant.Feeding in late autumn and winter pushes soft growth that frost destroys, and the nutrients mostly wash away. Stop feeding most plants from late summer, and start again in spring.
10. Feed the ground differently from a pot.In a border, bulky organic matter as an annual mulch does most of the work, because there is soil volume and biology to hold nutrients. Regular liquid feeding of established border plants is mostly unnecessary.
11. Water before you feed.Applying concentrated feed to dry compost puts a strong solution against dry roots. Water first, then feed, or feed with the watering.
12. Store and handle them properly.Original containers, closed, out of reach of children and pets, away from food. Never decant fertiliser into a drinks bottle.

Tips

• Granules at planting plus liquid feed from six weeks covers almost every container situation.
• Homemade comfrey liquid is a genuinely good high-potash feed for tomatoes and flowering plants, and costs nothing.
• A white crust on the compost surface means salts accumulating — water heavily from the top so it flushes through, and ease off the feeding.

Common mistakes

• Doubling the dose to catch up — Excess salts scorch roots and the plant looks worse rather than better. The label rate exists because of this.
• Feeding a wilting or waterlogged plant — Damaged roots cannot take up nutrients, and concentrated fertiliser around them causes further injury.
• Using high-nitrogen feed on flowering plants all season — It produces a large leafy plant with few flowers. Switch to high potash once flowering starts.
• Feeding into autumn — Soft late growth is exactly what frost damages. Stop feeding most things by late summer.

Alternatives

• Controlled-release granules: Coated, release with warmth and moisture over three to six months. Best for containers you cannot feed regularly. No control once applied.
• Liquid feed: Immediate, adjustable, leaches quickly. Weekly through the growing season. Best where you want to change the analysis as the season progresses.
• Organic slow-release meals: Bone meal, seaweed meal, pelleted poultry manure. Broken down by soil biology, so slower and weather-dependent. Good in the ground, less predictable in pots. Some attract dogs.
• Bulky organic mulch: The right answer for borders. Feeds slowly, improves structure and holds water, all at once. Not a substitute for feeding in a container.
• Homemade comfrey or nettle liquid: Comfrey for potassium and flowering, nettle for nitrogen and leaf growth. Free, effective and very smelly.

Questions people ask