How to Apply Granular Fertilizers
Apply granular fertilizer by broadcasting it either by hand or with a spreader. Using a hoe, spade fork, or rake work it into the top 4 to 6 inches of soil. You can also add small amounts to planting holes (be sure to mix it in with backfill soil) or to rows as you sow seeds or plant plugs. It’s a good idea to water after you have applied fertilizer to help it leach down toward the plants’ root zones. During the growing season, add supplemental fertilizer to the top inch of soil in crop rows, perennial beds, and around the drip line of trees or shrubs. (Read the label to find out how often applications should be made.)
How to Apply Liquid Fertilizers
Fast-acting liquid fertilizers are typically applied biweekly during the growing season. They are best used for container plantings and annuals. With flowering and fruiting plants, foliar sprays are most useful during critical periods, such as after transplanting or during fruit set, or periods of drought or extreme temperatures. For leaf crops, some suppliers recommend biweekly spraying.
Plants can absorb liquid fertilizers through both their roots and through leaf pores. Foliar feeding can supply nutrients when they are lacking or unavailable in the soil, or when roots are stressed. It is especially effective for giving fast-growing plants like vegetables an extra boost during the growing season. Some foliar fertilizers, such as liquid seaweed (kelp), are rich in micronutrients and growth hormones. These foliar sprays improve nutrient uptake by plants. Compost tea and seaweed extract are two common exam-ples of organic foliar fertilizers. To apply, simply mix the foliar spray in the tank of a backpack sprayer or hand mister set to emit a fine spray, and spray all your plants at the same time. (Never use a sprayer that has been used to apply herbi-cides.) Spray until the liquid drips off the leaves. Concentrate the spray on leaf undersides, where leaf pores are more likely to be open. You can also water in liquid fertilizers around the root zone. A drip irrigation sys-tem can carry liquid fertilizers to your plants. Kelp is a better product for this use, as fish emulsion can clog the irrigation emitters.
Tip: The best times to spray are early morning and early evening, when the liquids will be absorbed most quickly and won’t burn foliage. Choose a day when no rain is forecast and temperatures aren’t extreme.