There are two principal ways of growing annual and biennial flowers. The first is the method of sowing very early in the year in slight heat, hardening off gradually, and in due time planting out of doors.
The other method consists in sowing straight away in the open ground. This will, as a rule, be done in the case of hardy plants only. Most plants will perpetuate themselves in this way where allowed to do so. The Sweet William is a very successful subject when free to sow itself year after year, while, among annuals, the nasturtium, when once sown, is hard to extirpate.
A cold frame can be used for all but half-hardy subjects, but the ideal condition for culture is that of a greenhouse, with just sufficient warmth to keep the seedlings from receiving a check during nighttime.
Pans or boxes are suitable for sowing the seeds. They should be clean and dry, with potsherds placed at the bottom for drainage. Have ready some good fibrous loam, bringing it indoors a day or two before use, so that it may be in a warm and friable state.
With this will be mixed some well-decayed leaf-mould, in proportion of one-third to two-thirds of loam. The leaf-mould should be freed from worms by picking over, or by baking, if preferred. Add to the compost plenty of sharp silver sand (in proportion about 1/20), and turn the whole well over on the potting bench with a spade.
Lay some of the turfier pieces of loam, or some half-decayed leaf-mould, at the bottom of the pans, and fill up with soil, sifting the topmost layer with a fine-meshed sieve. Sow the seeds as thinly and evenly as possible, luxuriantly, and can be grown at little expense
Copyright, J. Murray Son and sift sandy soil over them, using only just enough to cover the seeds where fine. Sweet-peas may be put in an inch deep.
A splendid specimen of the China aster, a half-hardy annual that flowers
Syringe the pans lightly, and place them on the greenhouse shelf, having previously labelled each variety sown. It is best to cover them with sheets of brown paper, as the increased darkness will hasten germination.
The boxes must be examined daily and kept moist, always using a syringe in preference to a can. Pans of very fine seeds may be readily moistened by holding them in a tank, when the water will of course rise gently through the pan to the surface. Air must be given in plenty.
The time elapsing before germination takes place will vary with different seeds. As soon as the successive batches of seedlings appear, let the boxes or pans stand as close to the glass as possible, so as to avoid the seedlings becoming weakly and drawn.
When, a little later, the tiny plants can be held between the finger and thumb, other boxes must be prepared for their reception in the same way as the first.
Lift the seedlings in patches, using a wooden label to do so. A hole is made with a dibber, or piece of stick in shape like a bluntly pointed pencil, and the plants are put in up to their first leaves, pressing the soil firmly round them with the dibber and with the first finger and thumb of the left hand.
The seedlings should now be watered lightly. They should be shaded for the first few days in order to recover from the flagging which results from their shift. The earlier seedlings are transplanted the better, as a shift will often serve to arrest damping-off disease. Pull up any seen to be attacked badly. The distance at which seedlings should be set in boxes differs with the habit of the plant. The smallest should not have more than an inch of space, while for larger ones more is required, especially if they are to remain in their boxes until planted out.
As spring advances, the greenhouse should be full of nice stocky little plants. It will only be necessary to harden them off by placing the boxes in a cold frame, giving as much air as possible on all fine days. They may be stood outside the frame for a short interval before planting, their place being taken by successive batches from the greenhouse.
When the time comes for planting out, see that the soil of the beds is in a nice friable condition. If a single bed is devoted to one or more flowers, this should be deeply dug and manured previously.
If spaces in a mixed border are to be utilised, fork the ground as deeply as possible, first sprinkling a little superphosphate of lime or other suitable fertiliser.
No definite rule can be given as to the distance apart at which to put the plants, but eight inches to a foot will give a good general guide.
Many of the biennials will have been potted off and grown on separately before bringing them out of the greenhouse, and the "balls" of these plants should always be kept intact.
Small seedlings should be planted up to their lowest leaves, and all plants put in must be made firm. The plant is held lightly with the left hand, to keep it steady and upright. The soil is then firmed. Leave the soil on the surface loose but neat.
Let the plants have a good soaking of water after putting out.
Biennial plants may be raised in late summer or early autumn, to flower naturally the following year, or they may be treated as annuals by raising early in the spring in moderate heat, for flowering later in the same season.
Annuals for outdoor use, half-hardy and hardy, will, as a rule, be sown quite early in the year of flowering.
The following is a list of some of the best biennials and half-hardy annuals. Hardy annual flowers will find their place in a subsequent article.
Half-hardy annuals: Ageratum, China aster, brachycome, balsam, marguerite, carnation, diascia, dianthus, lobelia, mina lobata, French and African marigolds, nemesia, phlox drummondii, Iceland poppy, salpiglossis, schizanthus, statice, stock, tagetes, zinnia.
Biennials: Canterbury bell, campanula pyramidalis, evening primrose, linaria alpina, foxglove, East Lothian stock, wallflower, antirrhinum, Sweet William, forget-me-not.
The wallflower is a biennial that will repay attention. It flowers freely, is inexpensive, and most effective if planted in clumps or borders
Copyright, J. Murray Son