Organic Vegetable fertilizers

Organic fertilizers are gentle in nature and work slowly but long term. The organic fertilizers are avialable in various forms as dry fertilizers, ground minerals and liquid feeds.

Dry Organic fertilizers

Dried blood

A very quick-acting source of nitrogen,


A useful source of nitrogen and phosphorus, fairly quick acting.


Rich in phosphorus and also contains a little nitrogen. Fairly slow acting, depending partly on how finely it is nround.

Blood, fish and bone

Supplies phosphorus and some nitrogen but scarcely any potassium — any brand listing a %K will almost certainly have it added in chemical form.

Hoof and horn

Supplies mainly nitrogen. slow action,depending on how finely it is ground.

Seaweed meal

One of the few organic fertilizers containing a significant amount of potassium; also supplies nitrogen and a small amount of phosphorus, so is near to being a complete fertilizer like the chemical Growmore.

Calcified seaweed

Contains a very wide range of minerals,particularly calcium and magnesium, but none in large quantities, though it is said to help release phosphorus and potash locked up in the soil. It is valuable for poor soils needing trace elements and it can also be used instead of lime to increase alkalinity. It is claimed to work as a compost activator, not because it has a high nitrogen content but because its porous particles provide a good breeding ground for bacteria. This also helps its action in the soil.

Dried animal manures

There are several brands of dried animal manure on the market, providing all the nutritional benefits of farmyard manure without the constraints of its bulk. The problem is that some come from intensive farms and contain contaminants. If in doubt about a particular product, contact an organization concerned with organic growing.

Worm casts

A concentrated and balanced source of plant foods which you can produce at home. The same reservations as for manures apply to products in the shops, as the worms may be fed on the output from intensive farms.

Ground Minerals

Rock potash

From natural rock containing about 10 percent potassium, ground to a fine dust, some is available fairly quickly, but it will last in the soil for up to five years.

Rock phosphate

A natural ground rock providing a more lasting source of phosphorus than honemeal.


A ground rock similar to limestone, but containing magnesium as well as calcium. Use instead of lime for increasing the alkalinity of the soil, and for correcting magnesium shortage.


A ground rock made up mostly of calcium sulphate, which supplies sulphur to the soil. However, it is most often mixed with dolomite and used as a soil conditioner’ for clays, as it gradually helps the small clay particles to stick together and let water drain through.

Liquid Fertilizers

Seaweed solutions

Like calcified seaweed, liquid seaweed contains a wide range of minerals (the main plant foods and trace elements) but in small quantities. It is very useful as a foliar feed to correct deficiencies and to increase general plant health, especially of seedlings. It does not contain sufficient nutrients to feed plants in pots or high yielding greenhouse crops, though its effects are greater than a simple chemical analysis would indicate. Liquid seaweed also contains plant growth hormones; this supports claims that it helps rooting, gives plants some resistance to pests and diseases, improves fruit set, and extends the storage life of fruit and vegetables.

Liquid manures

Proprietary liquid manures are available, or you can make your own by suspending a sack of well-rotted manure with a water butt. These liquids contain significant amounts of the main plant foods (although not as much as most chemical liquid feeds) and a range of trace elements.

Comfrey liquid

This has a high concentration of potassium, and is therefore particularly useful for feeding fruiting crops such as tomatoes and courgettes. It is also the best feed for greenhouse plants in pots and houseplants. It contains concentrations of nutrients of the same order of magnitude as chemical tomato feeds.