Annual and Biennial Plants for Short Term
Annual and biennial plants are valuable in the garden for providing bright, colourful interest in a short space of time. This enables the owner of a newly established garden to fill large spaces between small, young shrubs, or to make use of a bed that has not yet been permanently planted.
An annual is grown from seed and is, by definition, a plant that completes its life cycle within one year. This means that during its growing season — which may be only four or five months — the plant develops from seed,, ripens fresh seed and dies.
In gardening terms, annuals generally embrace also biennial plants, sown in spring and in flower the following spring — and plants which are simply too tender to survive the British winter.
If you plan to sow or plant annuals in your garden, give a little thought to the colour and shape of the flowers, and consider whether they will complement each other and the existing plants. For instance, a shrub with soft, delicate pink flowers would be overwhelmed by a splash of stiff red salvias planted beneath its spread. On a more basic note, plan the height of flowers so that a splendid display of alyssum three or four inches high is not hidden behind towering antirrhinums two feet tall.
The Victorians were very keen on formal, carpet bedding, and we are all familiar with the massed, fruit salad effect of bedding plant layouts in parks and public gardens. Whilst these are attractive in their way, it would perhaps be a mistake to attempt to emulate them in a small, modern garden. Where a large area is to be filled with annuals, choose a colour scheme using just a small number of different plants, and avoid regimenting the plants in straight lines.
The short life of annuals can be turned to good advantage in this context, for it is possible to plant a bed of soft, delicate flowers in shades of pink, lavender, blue and white one summer, and transform it to a vibrant splash of red, orange and yellow the following year.
However, where the plants are intended to fill only a small space, it is better to use one variety rather than a busy mixture. This can be effective both in making a focal point in the overall planting scheme or continuing the colour theme of shrubs and permanent plants. White petunias can, for instance, enhance silver foliage plants whilst purple petunias follow through the darker shades of lavender or blue-grey foliage conifers.
Annuals do not only provide colour in the garden; many are suitable to grow for cut flowers. If you are a keen arranger it is worth setting aside an area for this purpose. Informal flowers with a sturdy stem are particularly useful, and favourites include sweet peas, stocks, larkspur and nigella (love-in-a-mist).
Flower arranging material can be supplied on an ‘everlasting’ basis if you grow a selection of flowers suitable for drying. These include statice, lunaria (honesty), helichrysum and poppies, which are grown for their seed heads.
The blooms should be picked when the flowers first open. Strip the leaves from the stem, tie them up in small bunches and hang them upside down in a dry, airy place. The flowers should be allowed to dry completely before use, but when they are ready will make attractive arrangements in subtle colours. Useful to have around at Christmas time, when fresh flowers are scarce, ‘ever-lasting’ flowers can also be carefully combined with candles and dried or painted leaves to make an unusual table decoration.
How to grow annuals and biennials
Annuals and biennials can be grown quite cheaply from seeds, or you can buy young bedding plants in small pots or trays from garden centres, shops and nurseries. The best buy is plants that look strong and healthy and are not yet showing colour.
These can generally be planted out as soon as they are purchased in early summer, but if the spring has been particularly late, wait until all signs of frost have passed. To remove annuals from their tray, break off each plant with a neat section ofand place in a prepared hole. Firm the soil around the plant and water well.
Annuals are not difficult to grow from seed, but they require two basically differing treatments. Some are known as hardy and can be sown directly into the soil outdoors, where they are to grow, either in spring or the previous autumn. Others are half-hardy and must be sown in the protection of a house or greenhouse in spring and transplanted into the garden in early summer.
When sowing seeds outdoors, the soil should not be soaking wet. It should, however, be quite fine and free from large stones, and should contain some organic material such as peat or vegetable compost and a little general fertiliser (too much can produce all leaves and no flowers). Tread the soil to firm, then rake the surface so that it is smooth and loose. Scatter small seeds on the soil, covering lightly with topsoil. Larger seeds, such as nasturtiums, should be planted from 1/2 to 1in deep. Lightly firm the soil.
It is important to thin the seedlings as soon as they are large enough to handle. Pull out weaker and smaller plants to allow the stronger ones sufficient space to develop properly. The distance required between plants obviously depends on their ultimate size. If you are growing flowers from seed, this information will be supplied on the seed packet.
Biennials are sown directly into the soil outdoors in late spring or early summer. It is necessary to set aside a small area as a ‘nursery’ bed, where the seedlings can be transplanted and grown on until autumn or the following spring. The young plants should then be positioned in the garden, where they are to flower. Flowers will be produced approximately twelve months after the seed was sown.
Seeds that need to be sown indoors require a seed sowing compost, available from garden shops. Seed pots or trays with smallholes should be filled with the compost and lightly firmed. Water well using a fine rose on the can. Allow to drain. Sow the seed thinly and cover with a layer of compost that is equal in thickness to the diameter of the seed. Tiny seeds, such as lobelia and begonia, do not require any covering.
Cover with glass or polythene and stand in a warm place until the seedlings germinate and show through. They should then be uncovered and transferred to a light position. When the seedlings are large enough to handle, transplant them into individual pots — peat pots are ideal — or trays, with 1-1/2in between plants. These should be filled with potting compost.
They can be planted out in the garden when all danger of frost has passed, but should first be hardened off gradually to ensure that they are fully acclimatised. This can be done by putting the plants outdoors in the daytime and taking them in at night, until the nights are a little warmer and the plants can be left out all night.
All annuals should be grown in a position that receives the maximum sunlight. In constant shade they become leggy and reluctant to flower. In autumn when they have finished flowering, the plants should be discarded and either burnt or composted.
Popular annuals and biennials include:
Alyssum. A low growing plant, up to 4in high, with white, mauve or pink flowers. Sow outdoors in April to May. Suitable to grow on a wall between stones, or as a rock plant as well as its more common use as an edging to.
Antirrhinum. The snapdragon that children love. A useful plant where height is needed, since it grows up to 30in tall, depending on variety. Flowers are red, orange, pink, yellow or white. Sow seed indoors from January to April for flowers from June to October.
Begonia semperflorens. The small, bedding begonia approximately 6in tall, with glossy leaves and tiny red, pink or white flowers. Useful for leaf colour and contrast; sow indoors in January to March for flowers from June to October.
Calendula. Known as pot marigold, calendula grows to 18in high, and flowers are cream, yellow or orange. Sow outdoors in March to May for flowers from June to September. Campanula (Canterbury bell). A biennial flower that should be sown outdoors in April to June and will flower from May to July the following year. Plants grow up to 30in tall with a mass of small, bell shaped flowers on each stem. Flowers are white, pink, blue and mauve.
Centaurea (cornflower). A hardy annual that is best sown outdoors in late August to early September for bloom the following June (can also be sown in April to May for bloom from June to September). Cornflowers are excellent for cutting, particularly the taller double varieties. Colours are blue, white and pink; tall varieties grow to 2ft high, dwarf to 9in.
Cheiranthus (wallflower). The warm, russet tones of this biennial are a familiar combination with bulbs in spring. Sow seeds out-doors in May to July to flower the following spring and summer. Plants grow 8 to 15in tall.
Eschscholzia. Known as Californian poppies, the flowers are saucer shaped and come in brilliant reds, oranges and yellows. Plants grow to approximately 12in high. Suitable for sunny, dry positions and where the soil is sandy. Sow seeds outdoors in September or March to April. Cut flowers off when dead, or seeds will spread and produce self-sown seedlings over a large area.
Helichrysum. There are two useful varieties of helichrysum. One is an annual known as straw flower, that grows up to 30in high. Seeds should be sown indoors in March or can be sown in the garden in April in warmer parts of the country. Flowers are suitable for drying.
Helichrysum lanatum is, strictly speaking, a shrub but it will not last outdoors through the winter. It is usually sold as a ‘silver leaf bedding plant, and its soft, downy leaves make an excellent contrast for brightly coloured flowers. Stems grow to 18-24in long with a tendency to curve and trail slightly.
Iberis (candytuft). An easy annual to grow. Flowers are white or shades of pink and purple and plants grow to approximately 9in high. Sow seed outdoors from March to June for summer flowering or in early autumn to bloom in late spring.
Lathyrus odoratus (sweet pea). Flowers are fragrant, come in a wide range of colours and are excellent for cutting. Sow seed outdoors in February to March. Plants grow to 7 or 8ft tall and need support from canes, twine or twiggy sticks. Distance between plants 6in.
Lobelia. A very familiar plant for edgingand borders, and in tubs, pots or hanging baskets. Plants have tiny white, blue or pinkish flowers, and trailing varieties are available. Sow seeds indoors January to April for flowers June to October.
Malcomia maritima (Virginian stock). Easy to grow for colour from spring to mid-autumn. Sow seeds outdoors in March and continue sowing right through to September for a succession of bloom. Useful to grow in crevices betweenstones. Plants grow to just 6in high.
Nicotiana. Tobacco plant is an extremely useful annual. Flowers are at their best in the evening and give off a delightful fragrance. Plant them near the house or patio to enjoy fully. A valuable plant, too, for cutting, particularly the variety with greenish yellow flowers. Sow seeds indoors in February to April for flowers July to September. Plants grow to approximately 3ft high.
Nigella. Known by the romantic name of love-in-a-mist, the soft blue flowers are surrounded by fine feathery leaves creating a hazy effect. Good for cut flowers. Sow seeds outdoors in March to April; plants grow 12-18in high.
Papaver (poppy). There are many varieties of poppy, but two most commonly grown are: Iceland poppy: Sow seeds outdoors in May to June for flowers the following year. Good for cut flowers. Grows to approximately 2ft high.
Shirley poppy: Sow outdoors in March to May for flowers June to September.
Petunia. Brightly coloured, bell shaped flowers are useful for a mass of colour approximately 12in high, and for pots and window boxes. Full sun is essential. Sow seeds indoors in March to April for flowers June to October.
Salvia. Large, bright red, conical shaped flowers with a rather stiff appearance but excellent for a splash of colour. Grows 8-18in depending on variety. Sow indoors in February to March for flowers June to September.
Tagetes erecta (African marigold). Double flowers, yellow or orange, grow up to 3in in diameter on straight stems 15 to 20in high. The effect is reminiscent of lollipops. Sow indoors in February to March and plant out in late May to June or sow outdoors in May for flowers from June to September.
Tagetes patula (French marigold). A less formal plant with smaller, single or double orange or yellow flowers. Plants grow 8 to 12in high. Sow indoors in March to April or outdoors in May for flowers from June to September.
Tropaeolum majus (nasturtium). A familiar climbing or trailing plant with red, orange or yellow flowers; large leaves can be used in salad. Grows best in full sun in soil with little or no food. Sow seeds out-doors in April to May for flowers June to October. Heights vary according to variety from 9in to 6ft.