Fertilizer is usually supplied to both potted and bedding plants at the time of planting. Over time the plants use up the fertilizer or the nutrients are leeched from the soil. Restoring the fertilizer is vital to ensure the health of the plant. The type of fertilizer depends on the needs of the plant variety. All plants require three basic elements---nitrogen, phosphorus and potassium--to produce healthy foliage, flowers or fruit.
Apply a 2-inch layer of compost to perennial beds in spring when new growth begins. Nutrients leech into the soil from the compost over the summer, restoring organic matter and nutrients to the planting bed. Apply ½ to 1 inch of fresh compost on top of the soil in perennial pots to replace organic matter.
Apply a granular fertilizer to perennial beds in spring and again at midsummer or when fruiting or flowering begins. Fertilize annual beds at mid-summer. Use a fertilizer specified for the plant variety in the recommended amount. In general, apply a general-purpose fertilizer such as 10-10-10 analysis if the exact fertilizer required is unknown.
Work the fertilizer into the soil 3 to 6 inches away from the plant stems, as the fertilizer can burn foliage if it makes direct contact. Apply the fertilizer between the rows if plants are laid out in a row-style planting.
Fertilize potted plants every two to four weeks from the time of planting if no fertilizer was added to the soil at planting time. If a time-release fertilizer was used at planting, begin restoring fertilizer eight weeks after planting. Apply a soluble houseplant fertilizer to foliage plants or use an all-purpose, balanced fertilizer for flowering or fruiting potted plants.