These are plants which take one year only to complete their life-cycle, I.e. they are sown, subsequently flower, ripenand die. The well-known is a typical example. In addition certain plants which are perennial in Nature, e.g. antirrhinum and lobelia, are often treated as in gardens as they do not generally survive the winter in our climate. Annuals may be divided into two main , the hardy and half-hardy.
These are usually sown outdoors from March to early May where they are intended to flower. Many will fare quite well on thin soils, provided there is sufficient moisture during the growing period. Finelike clarkia, godetia and mignonette need only be just covered with soil but the larger , like lupins, nasturtiums and require a covering of 1 1/2to 2 in.
Thin sowings are more economical, assown too thickly need drastic thinning later. Sow in shallow drills or broadcast, although the latter method means that weeding can only be carried out by hand. A better way is to in crossing drills, I.e. drills are taken out diagonally, first in one direction then at right angles, seed being sown at the points where they cross. Directly the have gained roothold, make the first thinning, followed by a further thinning about three weeks later. Wherever possible, thinning should be undertaken in showery weather. Some annuals, especially those with tap , e.g. eschscholtzias and godetias, do not transplant well. Always remove faded blooms and seed pods to prolong the flowering period.
Many hardy annuals can be sown in August and early September (provided theis sound) where they are to flower. They are usually in bloom at least a fortnight before those sown in spring. Examples are candytuft, collinsia, cornflower, godetia, limnanthes, nemophila, nigella and phacelia. All hardy annuals may be sown outdoors at this time of year, if they can be wintered in a or frame. Hardy annuals suitable for edging include candytuft, collinsia, cornflower, eschscholtzia, dwarf godetia, phacelia, Silene, . There are numerous hardy annuals described in this Encyclopedia including some too seldom grown by amateurs, but just as easy to cultivate as the more familiar kinds. See ADONIS, ALYSSUM, ANCHUSA, CALENDULA, CANDYTUFT, CLARKIA, COLLINSIA, ECHIUM, GILIA, GODETIA, IONOPSIDIUM, LARKSPUR, LAVATERA, LEPTOSYNE, LIMNANTHES, LINARIA, LINUM, MALOPE, MALVA, MENTZELIA (BARTONIA), MIGNONETTE, NIGHT-SCENTED STOCK, NOLANA, PHACELIA, SABBATIA, SWEET SULTAN, which represent a brief selection from the familiar and unfamiliar.
These are usually sown in seed boxes or pans in a greenhouse or frame during February to April using John Innes Compost. The seedlings are pricked off into boxes when large enough to handle and subsequently hardened off in a frame before moving to their flowering positions in late May and early June. Damping off is a common trouble among half-hardy annuals and other seedlings raised in the greenhouse. It causes shrivelling of the, the plants quickly wilting or toppling over. Lack of light, overcrowding and very wet soil lead to damping off but with Cheshunt compound will prevent the trouble. It is also possible to use a thiram seed dressing on many flower seeds before (the powder being puffed directly into the seed packet) but germination of some varieties may be affected and manufacturers’ literature should be consulted beforehand.
Many half-hardy annuals can be sown outdoors in May for flowering in late summer and early autumn. Examples are balsam, kochia, nemesia and Phlox Drummondii.
The following among many other half-hardy annuals are described in this Encyclopedia: AGERATUM, ALONSOA, ARCTOTIS, COSMOS, LOBELIA, NICOTIANA, PORTULACA, PETUNIA, RUD-BECKIA, SALPIGLOSSIS, SCHIZANTHUS, TITONIA, ZINNIA.
ANNUALS (HARDY AND HALF-HARDY) FOR CUTTING.
Sweet peas are, of course, indispensable and look very well mixed withgypsophila, despite the objections sometimes raised to this mixture by hortcultural snobs! Many more annuals last equally well in water. They, incluide asters of various types, calendula, clarkias, godetia, larkspur, sweet sultan, zinnia. The ‘Everlastings’ such as helichrysum and helipterum which are used in a dried state in winter, often in conjuction with ornamental grasses, are especially valuable.
A bed or border devoted solely to annuals (including both hardy and half-hardy types) is very attractive. If the border is large (say more than 8 ft. wide) a fair number of the taller annuals such as larkspur, lavatera and sweet peas should be grown and al varieties, irrespective of height, sown in large groups to secure the blest effect. The border ought always to slope from back to front so that the dwarf-growing annuals like adonis, ageratum, alyssum, ionopsidium, nolana and phacelia are never concealed by the taller varieties. Antirrhinum, clarkia, godetia and zinnia are suitable for the middle of the border. Half-hardy annuals like ageratum, antirrhinum and lobelia can be bought as young plants from a nurseryman. Sowing in straight drills should be avoided as irregular groups (preferably circular) are decidedly more pleasing where annuals are grown by themselves, especially in a border.
ANNUALS FOR SHADY POSITIONS.
Although most annuals prefer a sunny, open, some will do tolerably well in shade. They include adonis, annuus (common sunflower), nemophila, Phlox Drum-mondii and rudbeckia.