Annuals And Biennials

Seed is Nature’s usual means of increasing plant life and it is also the simplest method for the gardener when it comes to raising annual, biennal and, in some instances, perennial flowering plants. Gardens of modern houses tend to get smaller and smaller, due to the high cost of land, therefore the thing to do is to grow only the best plants and to grow them well. Inferior seed takes just as much time to sow and grow, the results will never be first-rate and the saving of a few pence is false economy. Only the best is good enough for the experienced gardener, as he knows from years of trial and error.

Flower seeds, in common with vegetable and other crops, are bred with great care and the plant breeder maintains a stud-book in which h keeps the parentage of hybrid plants in the same manner as with race horses, pedigree dogs and the like. All this takes time and costs money, but the results are far superior to plants pollinated haphazardly by bees and other insects.

Vast numbers of plants are raised from seeds but as far as flowers are concerned they are known as hardy annual, half-hardy annual, biennial and perennial.Hardy Annuals

Hardy Annuals

A hardy annual is a plant that is raised from seed, flowers, and dies a natural death within the four seasons. Given favourable weather a seed crop is harvested from such plants. However seed crops fail, or may be poor in some years, and it may take the seed grower a couple of years or longer to build up an adequate supply.

Half-hardy annuals

These are usually raised from seed sown under glass and the seedlings planted out where they are to flower when the danger of frost is past. Or some half-hardy annuals may be sown in the open ground in late spring to provide a late display. Flowering will continue until the autumn frost cuts down.the plants.


A biennial is sown one year, produces its flowers and dies the following year. Some biennials, the wallflower for instance, may prove to be short-lived perennials in some gardens, and the same applies to some half-hardy annuals, such as the antirrhinum, in a mild winter.


A perennial is a plant of any kind that lives for more than two years. It may be perennial in a greenhouse, others grown in the open are known as hardy perennials.

F, Hybrids Seed catalogues list many recent introductions as F, hybrids. This is the plant breeder’s abbreviated way of recording that the seed is the result of a controlled cross of two known parent plants, or to the scientist, the first filial generation. Such seed produces plants of superior vigour and uniformity and often the flowers are of more intense colour and larger than ordinary hybrid seedlings. It is, however, a long and expensive process to obtain such seed, therefore it costs more per packet. Also the complicated breeding programme has to be repeated, as seed saved from F, hybrids grown in the garden, would prove far from reliable.


Hardy Annuals

Seed of hardy annuals may be sown in the open ground where it is to flower; it is as easy as that. The main requirements are an open sunny position and a well-drained soil. Obviously the condition of the soil will be reflected in the quality of the flowers produced and to get the best results the ground should be forked over a few days before sowing and, where the soil is poor, work in bonemeal to a depth of 2 or 3 in. and at the rate of about 2 OZ. To the square yard. This is a fairly slow-acting fertilizer that will provide nourishment as the roots get down to it. Fresh manure is not a good thing for annuals as it encourages much soft leaf growth and not flowers.

Before sowing rake the soil level, removing large stones and hard lumps of earth. Most flower seed is small and does need a reasonably fine surface soil in which to germinate. Sow the seed broadcast or in drills and in any case sow thinly for germination of annual flower seed is usually good. This will reduce the wasteful job of thinning. Pelleted seeds make small seeds much easier to handle and thin sowing is easily achieved. This means that the seedlings will have sufficient space to grow without the check caused by thinning or transplanting.

Do not attempt to sow seed when the soil is wet and sticky, be patient and wait until it dries out. Seed sowing is controlled by the weather not by the calendar. If cloches are available these should be placed over the ground where the seed is to be sown and will not only keep the soil from being saturated, but will help to warm the seed bed and thus assist germination when the sowing is done. After the seed has been sown cover it lightly with soil and water with a can fitted with a fine rose. Water it just sufficiently to make the surface soil moist and if cloches are being used these should be replaced to cover the seed bed. Lithe ends of the cloches are closed with sheets of glass or by some other means marauding birds will be deterred.

Cloches are certainly useful to assist germination and protect tiny seedlings from heavy rain, but they must be used with discretion. It is all too easy to leave them over a seed bed until the soil has baked hard and any seed that has germinated is cremated by the hot sun before the seedlings have had a chance to make an adequate root system.

This can happen even without cloches during a hot, dry spell and in such conditions small seedlings may be shaded by small branches of evergreens, or some other means.

Where thinning of seedlings is necessary this should be done when they are about 2- 3 in. high and a final thinning should leave sufficient space for the plants to develop. After each thinning water the seedlings to settle the soil around the plants. The seedlings that have been removed may be planted elsewhere in the garden, but this is not successful with all annuals. As a rough guide to thinning the distance between each plant should be about three-quarters of the plant’s ultimate height; e.g. plants which will grow 1 ft. tall should be thinned to 9 in. apart.

Half-hardy Annuals

Many plants which we call half-hardy annuals are natives of much warmer lands where frost is unknown or a rare occurrence. Some are perennial in their native conditions. We must, therefore, encourage such seed to germinate with the aid of artificial heat in a greenhouse or frame as our conditions in February and March are too chilly in the open. Where the sowing is not done until April there should be sufficient heat from the sun to germinate the seed in an unheated greenhouse or frame. Some half-hardy annuals may be sown in the open in May or early June where they are to flower. These will, of course, not flower until late in the summer but are useful in prolonging the display after the plants raised under glass have finished flowering.

Seed of half-hardy annuals is sown in pots or boxes containing seed compost which is readily obtained these days in polythene bags at garden centres. It is moist and ready for use, which saves considerable time. Fill the container to within about in. of the top and press the compost down evenly and fairly firmly which is best done with a flat piece of board.

Sow the seed sparsely, then sprinkle a fine covering of compost over the seed and cover the container with a piece of glass, and a sheet of brown paper as shading. The compost should not require watering at this stage as it only needs to be moist. Remove the glass daily, wiping off the condensed moisture and reverse the glass when you replace it. When the seed germinates remove the glass and paper and put the container in full light in the greenhouse or frame.

When the seedlings are large enough to handle, that is usually by the time they have developed two pairs of leaves, lift them carefully by levering up the soil with a dibber and prick them out into another box, spacing them about 2 in. apart. Plant them firmly and water them into the compost. Keep them growing steadily under glass until the beginning of May. Then, if the weather is reasonably mild, stand the boxes in the open for a week or so to harden the plants before they are planted out where they are to flower. If the boxes have been in a frame it is a simple matter of just removing the frame light for this hardening-off process. Be sure that the boxes are standing level, and on a firm base, otherwise some plants may lack water. Give the boxes a good watering an hour or two before transplanting the seedlings so that they can be removed from the boxes with plenty of moist soil attached to their roots. Water them again when they are planted out.

Among the half-hardy annuals which may be sown direct in the open where they are to flower are aster, cosmos, African and French marigolds, mignonette and zinnia. The last two resent transplanting and germinate better when the soil is made firm after sowing. May or early June is the time to sow half-hardy annuals in the open in a sunny position and in well-drained soil.


Seed of biennial plants may be sown straight into a seed bed in the open ground in June, July or August. As the soil is warm germination is not delayed, provided the seed bed is kept moist. Another method is to sow in drills in a cold frame in March or April, or where only a small quantity of plants is required, to sow in pots or boxes in a cold frame or cold greenhouse. With the frame light in position there should be sufficient warmth to encourage germination. Artificial heat is unnecessary for seeds of hardy plants, in fact, it is not usually desirable.

Whichever method is used, sow thinly and do not make the common mistake of covering the seed with too much soil. As a general rule cover the seed with its own depth of soil. Nature just scatters it on the surface and lets the rain wash it in, but Nature is very wasteful, and sows with abandon.

Where the seed is sown in a cold frame leave some ventilation or the frame may get too hot. Some shading on the glass will also reduce the need for frequent watering and the same applies to seed sown in pots in a cold greenhouse which should be covered with brown paper or newspaper until the seed germinates. These are small points which make all the difference between failure and success. Biennials are sown one year and flower and produce seed the next, which completes their life cycle. Some will perpetuate themselves by self-sown seedlings, for instance, foxglove, forget-me-not, mullein, hollyhock, among many others.

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