When planting, dig a hole slightly larger than the root ball, set the plant in place at the same level at which it was growing, and carefully firm soil around the roots. New plants will need to be watered well after planting and frequently thereafter until they are established and new growth has started.
An application of soluble fertilizer, high in phosphorus, should be made after planting. A fertilizer such as 20-10-20 mixed at the rate of 0.5 pound per 100 gallons of water will cover 400 square feet. Do not apply fertilizer to dry soil.
MULCHING Adding a 2- to 3-inch layer of mulch is optional. It does add a decorative "finished" look as it reduces weeds and conserves soil moisture for better growth. The best mulches are organic, such as bark chips, pine needles, shredded leaves, peat moss or hulls. The following year, mix in the mulch to enrich the soil before planting.
Additional mulch can be added each spring, improving soil structure as years pass. Apply additional high nitrogen fertilizer such as ammonium nitrate or ammonium sulfate at the rate of 1 to 2 pounds per 100 square feet when adding fresh mulch. This will compensate for the nitrogen used during decomposition of the mulch.
FERTILIZING Most annuals do not require high levels of fertilizer, but will do much better if adequate nutrients are available. Application of a slow-release fertilizer (19-5-9) once or twice during the growing season is recommended. A rate of 1 to 2 pounds per 100 square feet is sufficient. As an alternative, you may use a soluble fertilizer such as 20-20-20 mixed at a rate of 1 pound per 100 gallons and applied every three to six weeks. Too much fertilizer can cause a build-up of soluble salts in the media which can damage plant roots.
MANICURING Many annuals, chiefly begonias, impatiens, coleus, alyssum, ageratum, lobelia, vinca, salvia and others, require little additional care. Their flowers fall cleanly from the plant after fading and do not need to be manually removed.
Others, such as marigolds, geraniums, zinnias, calendula and dahlias benefit from having faded flowers removed. This is known as "deadheading" and not only keeps plants attractive but also discourages disease and keeps plants from going to seed so the plants will produce more flowers and look tidier. Deadheading can be done with pruning shears or sometimes with the fingers.
A few annuals, primarily petunias, snapdragons and pansies, may need to be pinched back after planting or after the first flush of bloom to keep them compact and freely flowering. As new hybrids are created, this is becoming less of a maintenance requirement.
Some annuals, especially marigolds, benefit from being planted BEFORE they are allowed to flower. Marigolds and celosia should NEVER be planted with open flowers on transplants or the plants will be stunted and the bloom decreased.
Flowers for All Seasons Index