The annual flowers of the seedsmen are those that give their best bloom in the very year in which the seeds are sown. True annuals are those plants that complete their entire life-cycle in one season. Some of the so-called annual flowers will continue to bloom the second and third years, but the bloom is so poor and sparse after the first season that it does not pay to keep them. Some perennials may be treated as annuals by starting the seeds early; Chinese pink, pansy and snapdragon are examples.
The regular biennials may be treated practically as annuals; that is, seeds may be sown every year, and after the first year, therefore, a seasonal succession of bloom may be had. Of such are adlumia, Canterbury bell, lunaria, ipomopsis, oenothera Lamarckiana; and foxglove, valerian, and some other perennials would better be treated as biennials.
Most annuals will bloom in central New York if the seeds are sown in the open ground when the weather becomes thoroughly settled. But there are some kinds, as the late cosmos and moon-flowers, for which the northern season is commonly too short to give good bloom unless they are started very early indoors.
If flowers of any annual are wanted extra early, the seeds should be started under cover. A greenhouse is not necessary for this purpose, although best results are to be expected with such a building. The seed may be sown in boxes, and these boxes then placed in a sheltered position on the warm side of a building. At night they may be covered with boards or matting. In very cold "spells" the boxes should be brought inside. In this simple way seeds may often be started one to three weeks ahead of the time when they can be sown in the open garden. Moreover, the plants are likely to receive better care in these boxes, and therefore to grow more rapidly. Of course, if still earlier results are desired, the seed should be sown in the kitchen, hotbed, coldframe, or in a greenhouse. In starting plants ahead of the season, be careful not to use too deep boxes. The gardener's "flat" may be taken as a suggestion. Three inches of earth is sufficient, and in some cases (as when the plants are started late) half this depth is enough.
The difficulty with early sown seedlings is "drawing up," and weakness from crowding and want of light. This is most liable to occur with window-grown plants. Vigorous June-sown plants are better than such weaklings. It must be remembered that very early bloom usually means the shortening of the season at the other end; this may be remedied to some extent by making sowings at different times.
The "hardy" annuals are such as develop readily without the aid of artificial heat. They are commonly sown in May or earlier, directly in the open ground where they are to grow. Florists often sow certain kinds in the fall, and winter the young plants in coldframes. They may also be wintered under a covering of leaves or evergreen boughs. Some of the hardy annuals (as sweet pea) withstand considerable frost. The "half-hardy" and "tender" annuals are alike in that they require more warmth for their germination and growth. The tender kinds are very quickly sensitive to frost. Both these, like the hardy kinds, may be sown in the open ground, but not until the weather has become settled and warm, which for the tender kinds will not commonly be before the first of June; but the tender kinds, at least, are preferably started in the house and transplanted to their outdoor beds. Of course, these terms are wholly relative. What may be a tender annual in Massachusetts may be a hardy annual or even a perennial in Louisiana.
These terms as ordinarily used in this country refer to the northern states, or not farther south than middle Atlantic states.
Some familiar examples of hardy annuals are sweet alyssum, ageratum, calendula, calliopsis, candytuft, Centaurea Cyanus, clarkia, larkspur, gilia, California poppy, morning-glory, marigold, mignonette, nemophila, pansy, phlox, pinks, poppies, portulaca, zinnia, sweet pea, scabiosa.
Examples of half-hardy annuals are: China aster, alonsoa, balsam, petunia, ricinus, stocks, balloon-vine, martynia, salpiglossis, thunbergia, nasturtium, verbena.
Examples of tender annuals: Amarantus, celosia or coxcomb, cosmos, cotton, Lobelia Erinus, cobea, gourds, ice-plant, sensitive-plant, solanums, torenia, and such things as dahlias, caladiums, and acalypha used for bedding and subtropical effects.
Some annuals do not bear transplanting well; as poppies, bartonia, Venus' looking-glass, the dwarf convolvulus, lupinus, and malope. It is best, therefore, to sow them where they are to grow.
Some kinds (as poppies) do not bloom all summer, more especially not if allowed to produce seed. Of such kinds a second or third sowing at intervals will provide a succession. Preventing the formation of seeds prolongs their life and flowering period.
A few of the annuals thrive in partial shade or where they receive sunshine for half the day; but most of them prefer a sunny situation.
Any good garden soil is suitable for annuals. If not naturally fertile and friable, it should be made so by the application of well-rotted stable-manure or humus. The spading should be at least one foot deep. The upper six inches is then to be given a second turning to pulverize and mix it. After making the surface fine and smooth the soil should be pressed down with a board. The seed may now be sprinkled on the soil in lines or concentric circles, according to the method desired. After covering the seed, the soil should be again pressed down with a board. This promotes capillarity, by which the surface of the soil is better supplied with moisture from below. Always mark with a label the kind and position of all seed sown.
If the flowers are to be grown about the edges of the lawn, make sure that the grass roots do not run underneath them and rob them of food and moisture. It is well to run a sharp spade deep into the ground about the edges of the bed every two or three weeks for the purpose of cutting off any grass roots that may have run into the bed. If beds are made in the turf, see that they are 3 ft. or more wide, so that the grass roots will not undermine them. Against the shrub borders, this precaution may not be necessary. In fact, it is desirable that the flowers fill all the space between the overhanging branches and the sod.
It is surprising how few of the uncommon or little known annuals really have great merit for general purposes. There is nothing yet to take the place of the old-time groups, such as amaranths, zinnias, calendulas, daturas, balsams, annual pinks, candytufts, bachelor's buttons, wallflowers, larkspurs, petunias, gaillardias, snapdragons, coxcombs, lobelias, coreopsis or calliopsis, California poppies, four-o'clocks, sweet sultans, phloxes, mignonettes, scabiosas, nasturtiums, marigolds, China asters, salpiglossis, nicotianas, pansies, portulacas, castor beans, poppies, sunflowers, verbenas, stocks, alyssums, and such good old running plants as scarlet runners, sweet peas, convolvuluses, ipomeas, tall nasturtiums, balloon vines, cobeas. Of the annual vines of recent introduction, the Japanese hop has at once taken a prominent place for the covering of fences and arbors, although it has no floral beauty to recommend it.
For bold mass-displays of color in the rear parts of the grounds or along the borders, some of the coarser species are desirable. Good plants for such use are: sunflower and castor bean for the back rows; zinnias for bright effects in the scarlets and lilacs; African marigolds for brilliant yellows; nicotianas for whites. Unfortunately, we have no robust-growing annuals with good blues. Some of the larkspurs and the browallias are perhaps the nearest approach to them.
For lower-growing and less gross mass-displays, the following are good: California poppies for oranges and yellows; sweet sultans for purples, whites, and pale yellows; petunias for purples, violets, and whites; larkspurs for blues and violets; bachelor's buttons (or cornflowers) for blues; calliopsis and coreopsis and calendulas for yellows; gaillardias for red-yellows and orange-reds; China asters for many colors.
For still less robustness, good mass-displays can be made with the following: alyssums and candytufts for whites; phloxes for whites and various pinks and reds; lobelias and browallias for blues; pinks for whites and various shades of pink; stocks for whites and reds; wallflowers for brown-yellows; verbenas for many colors.
A garden of pleasant annual flowers is not complete that does not contain some of the "everlastings" or immortelles. These "paper flowers" are always interesting to children. They are not so desirable for the making of "dry bouquets" as for their value as a part of a garden. The colors are bright, the blooms hold long on the plant, and most of the kinds are very easy to grow. My favorite groups are the different kinds of xeranthemums and helichrysums. The globe amaranths, with clover-like heads (sometimes known as bachelor's buttons), are good old favorites. Rhodanthes and acrocliniums are also good and reliable.
The ornamental grasses should not be overlooked. They add a note to the flower-garden and to bouquets that is distinct and can be secured by no other plants. They are easily grown. Some of the good annual grasses are _Agrostis nebulosa,_ the brizas, _Bromus brizformis,_ the species of eragrostis and pennisetums, and _Coix Lachryma_ as a curiosity. Such good lawn grasses as arundo, pampas-grass, eulalias, and erianthus are perennials and are therefore not included in this discussion.
Some of the most reliable and easily grown annuals are given in the following lists (under the common trade names).