Shoots, roots and fruits
EAT YOUR VEGETABLES: Carrie Lyle posts on vegetable gardening each Tuesday.
Figuring out what fertilizer to use can be confusing. What exactly do those numbers on the package mean?
Gardeners have a saying about the nutrients essential to healthy plants: "Shoots, roots and fruits." Shoots refers to nitrogen, which promotes vegetative growth. Roots refers to phosphorous, which fuels root growth. And fruits refers to potassium, which promotes the quality and size of vegetables and flowers.
The numbers on a fertilizer package show the amount of nitrogen, phosphorous and potassium (N-P-K) it contains. A 7-4-5 fertilizer is composed of 7 percent nitrogen, 4 percent phosphorous and 5 percent potassium. The rest of the mix is inert filler.
The numbers themselves are not as important as the ratio — a 3-3-3 fertilizer has the same relative proportion of nutrients as a 1-1-1. Bigger N-P-K numbers don't necessarily make for a better fertilizer, though.
A fertilizer high in nitrogen encourages quick growth but, ultimately, produces a weaker plant. Slow, steady growth makes for a more healthy plant. Compost, which slowly releases nutrients over time, is a great general purpose fertilizer. Other excellent nutrient sources are blood, fish and bone meal and aged manure.
Photo credit: iStockphoto
