How do you use organic fertiliser?
Work it into the soil or compost before planting, or scatter it around growing plants and water it in. Always apply to moist soil, and always use the rate on the pack, because rates differ enormously between products.
Handcrafted in Stockport
All Purpose Fertiliser 4-4-4
Balanced 4-4-4, with the rate published for beds, pots and containers. 1.5kg from £12
Shop All Purpose 4-4-4The two ways to apply it
Worked in before planting. Scatter over the bed and mix through the top 10 to 15cm, or stir it through your compost before filling pots. This puts the feed where roots will grow into it and gives soil organisms a few weeks to start on it before the plant needs anything.
Top dressed during the season. Scatter around the base of a growing plant, keeping it off the stem and crown, lightly scratch it into the surface and water it in. Watering in matters: a granule sitting on dry soil is doing nothing.
How much: it depends on the product
There is no universal rate for organic fertiliser, and any page that gives you one is misleading you. Analysis ranges from under 1% nitrogen in garden compost to 13% in a concentrated extract, so the same weight of two different products can differ more than tenfold in what it delivers. The rate on the pack is the only one that applies.
As a worked example, here are the published rates for Dr Forest All Purpose Fertiliser 4-4-4. Treat them as an illustration of the shape of a rate table, not as a figure to carry across to a different feed.
| Use | Rate | How often |
|---|---|---|
| Beds and borders | 100 to 300g per square metre | Every 4 to 6 weeks in the growing season |
| Mixed into compost | 5 to 10g per litre of soil or compost, worked in thoroughly | Once, at potting or planting |
| Top dressing pots | 2 to 4g per litre of soil, scattered on the surface and watered in | Through the growing season |
| Light feeders | Lower end of the range | Every 5 to 6 weeks, or once per season |
| Medium feeders | Middle of the range | Every 3 to 4 weeks in the growing season |
| Heavy feeders | Upper end of the range | Every 2 to 3 weeks in full growth |
Rates for Dr Forest All Purpose Fertiliser 4-4-4, as published on the product page. Other feeds differ, so always use the rate on the pack in front of you.
The mistakes worth avoiding
Applying to bone-dry soil, so nothing breaks down. Piling feed against a stem, which can damage it. Reapplying after ten days because nothing has happened yet. Using a rate you read somewhere else on a product with a different analysis. And feeding in winter, when the soil organisms that do the work are barely active.
The feed in the worked example
All Purpose Fertiliser 4-4-4
Balanced 4-4-4 from ten named inputs, with rates published for beds, for mixing into compost and for top dressing pots.
Rates published for every use · Feeds for 6 to 8 weeks · Blended in Stockport
Shop All Purpose 4-4-4More organic fertiliser questions
How often should you apply organic fertiliser?What is 4-4-4 organic fertiliser?What is the best organic fertiliser for vegetables?Sources
- Royal Horticultural Society. How to feed plants. rhs.org.uk
- Cassity-Duffey, K. et al. (2020). Effect of soil texture on nitrogen mineralization from organic fertilizers in four common southeastern soils. Soil Science Society of America Journal 84(2), 534–542. doi.org
Soil notes
Get the evidence, not the marketing
Occasional notes from Stockport on feeding, soil structure and what the research actually supports, including the things that turn out not to work.
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