Fertilizers are categorized by the amounts of nitrogen, phosphorus and potassium, or the N-P-K ratio.
High Nitrogen Requirement
Vegetables that require high nitrogen levels include beets, Brussels sprouts, broccoli, cabbage, cauliflower, Asian greens, potato, leek, spinach and Swiss chard. High nitrogen ratio in fertilizers is 16-5-5. Soak full 4 gallon bucket of grass clippings in water 1-2 days. Dilute your grass tea by mixing 1 cup of liquid grass into 10 cups of water.
Medium Nitrogen Requirement
Vegetables that have a medium or balanced nitrogen requirement include chicory, asparagus, eggplant, lettuce, garlic, onion, squash, pepper, tomato and sweet corn. A balanced nitrogen ratio in fertilizers is 16-16-16.
Low Nitrogen Requirement
Vegetables that require a low level of nitrogen include cucumber, carrots, fava beans, peas, radish, parsnip, turnip and rutabaga. A low nitrogen ratio in fertilizers is 5-10-10.
Nitrogen for Fruit Bearing Vegetables
The fruit-bearing vegetables such as eggplant, cucumber, pepper, melon and tomato need a good dose of nitrogen in order to start off a healthy plant. But later as the fruit starts to form they need a fertilizer that has high concentrations of potash.
High Phosphorus Requirement
Pod and fruit crops require more phosphorus. Bonemeal and rock phosphate are typical sources.
High Potassium Requirement
Root vegetables require more potassium. Collect used coffee grounds. Dig 6 to 8 inches beneath the surface of the ground or plant container, then mix coffee grounds into the soil. Liquid: about 1/4 coffee and 3/4 water apply weekly.
Generally, the leafy vegetables and corn need greater quantities of nitrogen, the pod and fruit crops require more phosphorus, and the root vegetables need an extra kick of potash.