Plants require many nutrients the main ones being nitrogen, phosphorus(in phosphate) and potassium(in potash). Each of these ingredients can be bought separately, but most gardeners prefer to use general fertilizer containing all three such as Growmore. It contains seven percent nitrogen,seven percent phosphorus and seven percent potassium. The ingredients are sulphate of ammonia, superphosphate of lime and solphate of potash.
Another popular general formula is John Innes base fertilizer containing hoof and horn manure, superphosphate and suphur of potash. The analysis is 5,1 percent nitrogen 6,4 percent phosphorus and 9,7 percent potassium.
Fertilizers can also be applied to the roots of a plant as a liquid for quick absorbtion. Liquid fertilizers can be bought as abalanced feed for general purposes or as special mixtures for particular plants. General fertilizers are also sold as foliar feeds-liquids which are absorbed quickly through the leaves when applied with a watering can.
Most plants in planters are grown in potting mixes with little or no nutrients in them when that is the case then the gardener must provide the necessary fertilizers for good plant growth.
Choosing the correct fertiliser: Whether you are using a natural fertiliser, or an artificial one, make sure you are treating your plants properly. For example, are you remedying a general soil problem, or feeding a particular plant to make it flower more profusely? Once you've decided which fertiliser to use, you have several ways to apply it.