As you will see from the table at the end of this section, fertilisers are grouped into those which occur naturally (organic) and those which are manufactured by various chemical processes (inorganic).
There is much debate as to whether organic is best for the environment, health etc. but whichever you choose will work for you.
Generally organic fertilisers are less controlled in their make up as nature is unpredictable and therefore the table should be used as a guide only. Inorganic fertilisers are controlled in their make up and are therefore predictable. Whichever you use, read the instructions and stick to them, you will need far less than you think.
Inorganic fertilisers have a more rapid effect on the crops as the chemicals are rapidly absorbed into the soil and become available to the plants quicker. This is good if your plants are suffering, but bad if you want the effect to last as you may need to re-feed for a crop that is in the ground for an extended period. Organic fertilisers are slower to react as it takes time for bones and the like to be absorbed into the soil and broken down by the microbes but the effect is long lasting and the need to re-feed for one crop is unlikely.
If you are a beginner it is better to stick to one of the balanced fertilisers as you will be guaranteed that the crop is getting at least a decent supply of food. As you become more experienced it can be interesting to start mixing your own formulations from the base fertilisers to suit the particular crop you are growing, you can get some real whoppers this way.
Not included are the self produced fertilisers (no not like that!) which are the favourite of many organic gardeners. Comfrey and farmyard manure are just two of the products that can be soaked in water to provide a rapidly acting liquid fertiliser. Take advice from someone who already does this before you try or experiment very carefully as over strong liquid will kill rather than cure.
There are also concentrated and dried manures, both cow/horse and chicken which are commercially produced and are used like balanced fertilisers. Again these are somewhat unpredictable in their make up but contain all the trace elements you could need and can produce wonderful results if you cannot get hold of basic manure.
The rates of application have been extracted from the back of various manufacturers bulk sacks so should be as definitive as you can get.
If viewed on a mobile device, the column order is Product / Application rate/ What is it? / Organic / Used for
| Product | Application rate | What is it? | Organic | Used for |
|---|---|---|---|---|
| Organic pelleted chicken manure | See pack | Chicken manure – good source of nitrogen, potassium and phosphorus. Not as concentrated as Growmore. | Yes | A good general fertiliser for adding to the soil in the spring before planting - good for most crops, but don’t use around acid loving plants like blueberries |
| Bone Meal | 2-4oz/sq yard | Ground up animal bones. Smaller amount of nitrogen and higher phosphates. | Yes | Promotes root growth. Add to the soil before planting or sprinkle around existing plants. Good for flowering plants. |
| Calcified seaweed | 2-4oz/sq yard | This is not seaweed, but a kind of calcified cold water coral. Consists of about 50% calcium, 5-10% magnesium carbonate and a wide range of beneficial trace elements. | Yes | Neutralises soil – in addition contains some minerals. Good for alliums – leeks, onions and garlic. Can help improve drainage on heavy soils. Can be applied at any time of year. |
| Epsom salts | 2oz per gallon | Epsom Salts, common name for colourless or white crystalline salt found in the minerals kieserite and epsomite and in mineral waters. | Yes | Curing magnesium shortage – yellowing leaves. |
| Fish blood and bone | 2-4oz/sq yard | General purpose balanced fertiliser. Good source of nitrogen, potassium and phosphorus. Organic version of Growmore. | Yes | A good general fertiliser for adding to the soil in the spring before planting - good for most crops. |
| Growmore | 2oz/sq yard | Good source of nitrogen, potassium and phosphorus. General purpose balanced fertiliser. | No | A good general fertiliser for adding to the soil in the spring before planting - good for most crops. |
| Nitrate of chalk | 1oz/sq yard | Fast acting source of nitrogen. Contains calcium. | No | Spring/early summer feed for brassicas, beetroot, celery and other leafy crops. |
| Nitrate of soda | 1oz/ sq yard | Very fast acting source of nitrogen. | No | Spring/early summer feed for brassicas, beetroot, celery and other leafy crops. |
| Potato fertiliser | 2oz/ sq yard | A strong version of Growmore. | No | Balanced fertiliser for potatoes (very strong as they are greedy crops). Add to the soil at point of planting. |
| Sulphate of ammonia | 1oz/sq yard | An inorganic salt with high levels of nitrogen and sulphur. | No | Provides nitrogen for acid loving plants, potatoes, corn & rhubarb. A good compost accelerator. Can be applied at any time. |
| Sulphate of potash | 1oz/sq yard | An inorganic salt with high levels of potassium and sulphur. | No | For fruit and flowers e.g. a feed for flowering tomatoes/chillies/fruit bushes when the root has set. Good feed for garlic in early spring. |
| Superphosphate of lime | 1oz/sq yard | A compound produced by treating rock phosphate with sulfuric acid or phosphoric acid, or a mixture of the two. It is the principal carrier of phosphate, the form of phosphorus usable by plants. | No | Promotes strong root systems. Add at the time of planting or around plants. |
| Groworganic manure | See pack | Concentrated farmyard manure General purpose balanced fertiliser. | Yes | A good general fertiliser for adding to the soil in the spring before planting - good for most crops |
| Tomorite concentrate | See pack | High levels of potassium. Made from chemically synthesised courses of nitrogen, potassium and phosphorus. | No | For fruit and flowers e.g. a feed for flowering tomatoes/chillies/fruit bushes |