Contributed by Steve Lucas
N = NITROGEN which promotes leafy growth and is therefore good for brassicas and non-flowering plants
P = PHOSPHORUS which promotes a good root system and is therefore particularly good for all root crops. It is also especially useful when planting new roses or shrubs / trees as it helps them to establish a good root system
K = POTASH (Latin name is Kalium) this is for any plant which flowers or bears fruit so is used on things like soft fruit, tomatoes, cucumbers, peas and beans to name just a few of the vegetables it helps, as well as all plants grown purely for their flowers. It also helps to produce healthy growth and resistance to diseases
Fertilisers stocked in the allotment shops are either “straights” or “compound” Fertilisers, the former covering just one of the above elements and the latter two or more of the above. All our fertilisers are bought in 25 kg sacks and then broken down into smaller quantities for our members.
The fact that we buy stock in bulk at pre-season prices with large discounts and the lack of posh packaging makes these items much cheaper than in Garden Centre’s and chain stores etc. The fertilisers we currently stock and the percentages of Nitrogen, Phosphorus and Potash they contain are as follows
Some of the above fertilisers will also contain TRACE ELEMENTS such as Magnesium, Manganese, Iron & Boron to name a few
In addition to the above granular fertilisers there are also various liquid versions which all have slightly different combinations of N P & K and some of these also have trace elements. I hope this has helped you to understand the importance of N P K and to work out which fertiliser you need for your plants.