An annual, from the point of view of the amateur gardener, is any plant which must be replaced each year and which flowers only once in its life. Annuals generally are grown from seed though you can certainly purchase them every spring in 4- and 6-packs at the local home improvement store.
The chief advantage of annuals over perennials is their low cost. Thousands of plants can be grown from a single packet of seeds. Annuals are also very decorative and provide the best source of flowers for cutting during their long blooming season.
Their chief disadvantage is the late date at which they bloom. If annuals are used alone in a bed or border, a good part of the season will pass with little to show in the way of color.
Annuals are also of use as a filler between shrubs set some distance apart. This permits the shrub to grow, yet prevents too stark an appearance.
The sowing of annuals, of course, depends upon the class to which they belong. The hardier flowers, such as larkspur, poppies and cornflowers, can be profitably planted in late fall. The ground preparation must be just as careful as for spring planting. Planting in fall is advantageous since it permits the flowers to get an early start the following spring. Certain other hardy annuals can be planted early in spring as soon as the ground is workable.
It is a good idea to start some of the less hardy annuals in seed pots, or in coldframes, as early as March. Otherwise, these plants cannot be set out until all danger of frost is gone.
Outdoor planting of annuals in the spring follows thorough soil preparation. The seedbed must be carefully pulverized with a rake after it has been prepared and prior to planting. Eliminate all lumps.
The seeds are sown broadcast in the patch selected and then are lightly covered with soil. The soil may be gently tamped after the covering is completed. The patch should be identified with a stake and some sort of sign.
Flower seeds are best planted near the surface. In no case should they be sown more than 1 inch deep. The seeds of larger plants which have a strong growth, such as sunflowers, can be planted in hills spaced from 2 to 4 feet apart.
Often, annuals are planted in rows. This method is used when a cutting garden is being grown. To do this, dig a shallow trench not more than 1 inch deep with a trowel, or your fingers, and then place the seed in the trench. Sow more seed than appears necessary and then trim out after the plants appear above ground. Thinning is required, in any event, for a good crop of annuals, if only to insure sufficient room for each plant.
Transplanting is a considerable shock in the life of a plant and unless it is carefully done, the plant will die. It is a good idea to expose coldframes and potted seeds to the outside air for a time before transplanting, in order to prevent shock. Slowly increase the exposure time each day. All the soil in the frame or pot should be used when transplanting.
Transplanting should be done on a cloudy, damp day, if possible. If the soil is dry, it should be watered before transplanting and then thoroughly after the plants are in the ground. If the day is sunny, some sort of shade should be provided for the newly transferred plants. As soon as the plants are established, these protective coverings can be removed.