Mineral fertiliser feeds the plant like a quick meal: instantly available, but soon gone again and washed into the groundwater. Organic fertiliser takes a quite different path. It feeds the life in the soil first, and that then supplies the plant, steadily and gently.
This difference is the heart of organic feeding. Once you understand it, you no longer feed hectically by symptom but build up a fertile, living soil over the years. And that soil carries the plants almost by itself.
Feed the soil, not the plant
A healthy soil is full of bacteria, fungi and worms. These creatures break down organic material and release the nutrients bit by bit to the plant roots. Organic fertiliser is therefore only raw material for this soil life, not finished plant food.
That has three big advantages. The nutrients come slowly and evenly, instead of in a surge half of which washes away. The humus content rises, the soil stores more water and turns crumblier. And the soil life stays active, which makes plants more resilient. So you invest not in one season but in the soil.
NPK: what the three nutrients do
Every fertiliser carries the three letters N, P and K. Whoever knows what they stand for feeds precisely instead of by feel.
The three main nutrients
- Nitrogen (N) for the leaf
The engine of growth. Nitrogen drives leaves and shoots. Too little and the plant stays pale and puny, too much and it turns soft and susceptible.
- Phosphorus (P) for root and fruit
Important for root formation, flowering and fruit set. A good phosphorus level helps young plants establish and promotes a rich harvest.
- Potassium (K) for robustness
Strengthens the cells, improves the flavour of the fruit and makes the plant more resistant to drought, frost and disease.
- And the rest
Add to that magnesium for the leaf green and many trace elements. A humus-rich soil supplied with compost provides most of them along the way.
The most important organic fertilisers
What you need for feeding
- Compost as the foundation
Your own compost is the basis of any organic feeding. It provides all nutrients in balance, humus and soil life at once.
- Horn shavings and horn meal
A pure, slow-acting nitrogen fertiliser. Shavings work over months, the finer meal faster. Ideal for hungry heavy feeders in spring.
- Well-rotted manure
Cattle, horse or sheep manure provides nutrients and plenty of organic matter. But it must be aged; fresh manure burns the roots.
- Plant brews and rock flour
Nettle brew brings quick nitrogen, comfrey brew lots of potassium. Rock flour provides minerals and trace elements and activates the soil.
How to feed properly
Lay the base with compost
In spring, bring a layer of ripe compost onto the bed and work it in shallowly. That is the basic supply on which everything else builds.
Feed to the crop's appetite
Not every plant needs the same. Heavy feeders like cabbage and tomato get extra horn shavings, light feeders and legumes hardly anything. Which crop draws how much is in Planning crop rotation.
Give it at the right time
The main need is in spring at the start of growth. Slow-acting fertilisers like horn shavings you give early, fast brews during the main growing season.
Stay sparing
Organic does not mean any amount. Too much compost or manure over-supplies the soil too. Rather feed in moderation and watch how the plants respond.
Feed the soil, not the plant. Compost as the base, supplemented in a targeted way, and always rather a little too little than too much.
The core rule of organic feeding
Frequently asked questions
What is the difference from mineral fertiliser?
Mineral fertiliser makes nutrient salts available to the plant at once, acts fast but washes out easily and builds no humus. Organic fertiliser must first be unlocked by the soil life, acts more slowly and sustainably and improves the soil for good.
Is compost alone enough as fertiliser?
For many crops yes. Compost provides balanced nutrients and humus. Only hungry heavy feeders like cabbage, tomato or squash appreciate an extra dose, such as horn shavings. Light feeders manage perfectly on compost.
When is the best time to feed?
At the start of growth in spring. Slow-acting fertilisers like horn shavings or compost you give early, so they are unlocked in time. Liquid brews you use in a targeted way during the main growing season. From late summer, feeding is no longer nitrogen-heavy.
Can I over-feed with organic fertiliser?
Yes, that happens too. Too much manure or nitrogen-rich brew drives soft foliage prone to aphids and disease. The upside: organic fertilisers act more slowly, so the risk of over-feeding is lower than with mineral ones.
What is rock flour good for?
Rock flour provides minerals and trace elements and binds odours, for instance in the compost or manure heap. As the sole fertiliser it is not enough, but as a supplement it activates the soil life and rounds off the supply.
