Fertilizer by the Numbers

The application of fertilizer in the vegetable beds, flower beds, around trees and shrubs and the lawn is a Spring tradition.  Properly used, fertilizer will give vigour to the growth, help with flower and fruit development and encourage resistance against disease and pathogens.

But what do the numbers mean?

The three numbers listed represent the percentage of macro nutrients found in each bag.  The first number is for nitrogen, the second is for phosphorous and the third is for potassium.

  • Nitrogen is used by the leaves in plants to increase growth rate and vigour.
  • Phosphorous promotes flower bud and root development.
  • Potassium assists in the plants overall hardiness and disease resistance.

6-12-12 is a basic vegetable garden fertilizer.  The 6% nitrogen level will promote for leafy vegetables such as spinach, lettuce and corn, and also assist foliage in root crops like potatoes and carrots.  Beans are self sufficient in nitrogen, as their roots have bacteria that affix nitrogen to the soil.

The 12% phosphorous will help in growing all root vegetables.  It is also necessary to develop healthy flowers in squash, cucumber and melons, as well as edible flowers like broccoli and cauliflower.

Potassium works at the cellular level in plants.  Better cell structure helps  the plant when it is under stress from drought, disease and even helps the plant recover after insect infestations.

Some of the other fertilizers readily available include the balanced varieties, such as 10-10-10, or 15-15-15.  These are general purpose and are great for use around trees and shrubs.  For flower gardens I always recommend an 8-20-12.  Lawns have specific needs that will be covered in the next post. Until then, Happy Gardening!

Garth Davey, April 2021

Questions? Email Garth @Questions@kbfarms.ca.