If I had a penny for every time I brought up the subject of feeding plants, I’d be very rich indeed. Just as the human body needs the right food for health and vitality, so do your garden lovelies
In the food world, we have become quite used to reading pack labels to establish ingredients –low fat, salt content, etc. so I’m now advocating that you do the same with plant fertilisers. First let’s take a brief look at the three major nutrients that are vital to a plant to guarantee it a healthy life. Understanding this will take you a long way to success.
This is the plant’s leaf maker and is a major component of chlorophyll – the stuff that makes leaves green. Plants that will have the greatest need for nitrogen are those vegetables grown for their leaves and lawn grasses.
If your plant’s lower leaves are turning yellow, but the growing tip remains reasonably green, your plant is calling out for nitrogen. Iron is needed when the upper leaves look mottled green/yellow. However, if your flowering plant is producing lovely leaves, but it isn’t flowering then the chances are you are feeding it too much nitrogen and not enough potassium (see below).
Often described as the plant’s root-maker. It’s a component of DNA and regulates the rate of growth and reproduction of cells at the plant’s growing tip (and this includes the growing roots too) and germination of seeds. In a nutshell, no phosphate, no plant growth!
Potassium is needed by the plant to set flower buds, which then go on to give the plant sufficient energy for the buds to open to then set fruit and seeds.
If your flowering plant is either not flowering at all, or getting to the point of producing flower buds that fail to open, then the nutrient needed is potassium.
All plant fertilisers must declare their nutrient content on the label. It’s expressed as a ratio, giving the values in a block of three numbers. For example, the plant food that I always recommend for flowering plants – a slow release granule product where one application will last for six months – the NPK ratio looks like 12:7:19. This reading tells me that there is a higher ratio of potassium to nitrogen and therefore perfect for all plants but the grass (with tomato food this will be twice the amount).
Slow release v liquid
Unless you can guarantee that your soil is well hydrated at all times, I would choose granules to scatter around the base of each plant.
Valerie McBride Munroe
Find more gardening articles by Valerie in the Homes & Gardens section