Annuals And Biennials For Window Boxes And Other Containers

Annuals are ideal for containers of all kinds, but particularly window boxes, jardinieres, strawberry jars, patio pots and tubs. Many remain in flower for weeks — even months — their gay colours brightening sombre spots and masking dull features.

Where window boxes are used they must always be securely fastened and ideally should be 1 in. wider than the sill and have wedges pushed under the front edges so that they tip slightly backwards. Drainage holes are not essential if plenty of drainage material (crocks covered with rough peat) is placed in the bottom and they are carefully watered. Loose liners are the ideal for as each crop of flowers becomes shabby these can be lifted out and changed in minutes by previously prepared replacements.

Window boxes can also be fastened to brackets secured to boundary walls, which affords interest and provides more space and colour in very small gardens. Arrange these at different levels for a more artistic effect.

Annuals And Biennials For Window Boxes And Other Containers

Hanging baskets have many uses. They can be hung from rafters in sun lounges, pergola arches and over doorways or the flat-backed kinds may be fixed to house walls. These again must be very secure and lined with moss or green plastic sheeting (with a few holes pierced round the sides about 1 in. up from the base to avoid waterlogging after storms) to conserve moisture in dry weather.

Tubs full of annuals, urns and pots can be stood about in various situations or a strawberry pot used to mask an obvious and inconveniently sited manhole cover. Stand terracotta strawberry pots in large saucers and fill these with water daily. This is the best method of watering. The polyester and glassfibre types should not be filled too full as these have no drainage holes and being non-porous have to be watered from the top. Feed all container plants occasionally — foliar sprays are ideal in summer — and change the soil annually.

F, hybrid varieties (first cross seed) are preferable in some instances but not invariably, as the larger flowers produced can suffer in storms and windy situations.


Alyssum maritimum, now more correctly Lobularia maritima, is the familiar sweet alyssum so popular for edging window boxes, borders and beds or for growing in pavement crevices. Strictly a perennial, it is invariably grown as a hardy annual and flowers continuously from June until October. Growing 6 to 9 in. high, it has tufts of small pointed leaves and racemes of white, honey-scented little flowers. Varieties with pink and violet flowers are available. Seed can be sown where the plants are to flower in spring or raised earlier under glass and after hardening off planted outside towards the end of May. Germination takes about five days.


Bellis perennis is the English daisy, a perennial which has produced a number of fine double varieties. These come true from seed when treated as annuals or biennials. The flowers are large and showy on 5 to 6-in, stems, the colours white, pink or red and the simple oval leaves ground hugging. Seed is sown in June, when they are treated as biennials, in a nursery plot outside and, after thinning and growing on, the young plants are set in their flowering positions in early autumn. They can also be raised under glass, by sowing seed in June or July and transferring the seedlings — by stages — to 4-in. pots. Daisies like rich, moist soil and flower out of doors from May to July. They can be

used in beds as well as containers, or as carpets in light shade beneath trees, or grown as cut flowers.


Dwarf bedding dahlias are often treated as annuals and make useful container plants with a flowering season extending from June until frosts cut them in early autumn. Seed production does away with the chore of overwintering the tubers and the results are reasonably predictable and true to type. Treat them as half-hardy annuals and pinch out the growing tips when the plants are 3 to 4 in. high to induce a bushy habit. The seedlings should be separately potted and when weather conditions allow may be turned out and planted. They need full sun and rich soil, with plenty of water, and the occasional feed in the growing season. The most suitable races for container work are such kinds as the double Dwarf Early Bird Mixture or Unwin’s Dwarf Mixture; both in bright colours and about 12 in. tall. If singles are sought any of the Coltness types, such as Sparkle Mixed, are ideal although they are taller (15 to 18 in.).


Lathyrus odoratus is the sweet pea, a much-loved flower with a delightful colour range and exquisite scent. Whilst most sweet peas are more suitable for the cut flower bed or mixed border, there are dwarf strains well adapted for use in window boxes and other containers. They include the American Knee-Hi which grows around 2 ft. and needs no staking. Each flower stem carries five to seven blooms, the colours are as varied as their taller counterparts. The Little Sweetheart varieties are still more compact, being a mere 8 in. high in various colours. For cultivation details see p. 116.


Limnanthes douglasii is the meadow foam or fried egg plant, a delightful little Californian, whose white, yellow-centred, saucer-shaped flowers seem irresistible to bees. Seed should be sown where the plants are to flower in autumn or spring. Germination takes about three weeks, when the young plants should be thinned to 3 or 4 in. This is a beautiful little plant for early summer ,flowering, when it dies down and can be replaced if required. In the garden enough self-set seedlings come up each spring to maintain the stock. The height is 9 to 12 in.


Chrysanthemum parthenium is more likely

to be found in seed catalogues under Matricaria eximia than its proper name, for which reason it is included here. The type, a British perennial with small white daisy flowers and aromatic deeply cut foliage, is not worth growing, but the double-flowered varieties with branching stems and many ball-like heads are really arresting and stand well in containers. Typical sorts are Silver Ball, Golden Ball, and Lemon Ball, all 9 to 12 in. high with fin. Blooms, and there is a golden-foliaged form aureum, which makes an attractive background for blue flowers.


Stocks make good container plants if they can be sited away from strong winds which can snap the stems unless these are individually staked. They appreciate deep, rich, moist soil and given this thrive in full sun or partial shade. There are three main groups, all derived from Matthiola incana; the Brompton or Queen stocks which are treated as biennials, seed being sown outside in June or July and then put out in their flowering positions the following September (or April in exposed areas); ten week stocks, which are grown as half-hardy annuals and planted out in May from spring-sown seed under glass, and intermediate or East Lothian stocks, which can be grown as biennials or alternatively as annuals for autumn flowering.

In all cases the colour range is varied, from white and apricot to rose, lilac, carmine, mauve, purple and light blue. Since those with double flowers are the showiest always purchase seed from a reliable grower stocking good strains and check the seedlings before growing these on or pricking out. It is the light green foliaged seedlings with long leaves which produce double flowers — the dark green, short-foliaged ones are most likely to be single. Although seed deteriorates with keeping, the most persistent of life and able to survive are also doubles. Incidentally the germination of stocks takes about ten days.

In addition to their usefulness in containers, stocks merit a place amongst mixed bedding as well as for cut flowers or pot work indoors. Their rich scent, silvery foliage and long spikes of flowers commend them to most gardeners, so plant them in positions where these can be enjoyed, such as close to the house or near sitting out areas in the garden.


Petunias are among the most desirable container plants for they are cheap and easy to raise and flower all summer. They have showy, trumpet-shaped flowers and entire, rough, rather stocky stems and leaves. If the stems become leggy, the flowering shoots can be cut back to young growths farther back along the stems. These soon take over and throw up fresh flowers. This operation can be repeated several times in a season if one feeds the plants in between times. The F, hybrids and doubles are more showy when grown as pot plants or in protected situations, but wind can damage the brittle stems, so that the smaller singles are often more useful in window boxes and hanging baskets.

A strawberry pot filled with pink, mauve and blue petunias makes a magnificent ‘all round’ feature for summer and the leaves and flowers completely hide the pot in a few weeks.

Petunias should be treated as half-hardy annuals, the seed germinating in about fourteen days and, like stocks, the smaller seedlings are the ones which produce double or most brightly coloured flowers. A light rich soil suits them best, with plenty of water during the growing season. They are highly susceptible to frost and do not take kindly to drought.

For winter bloomers, seed can be sown in a cold frame in June or July, the seedlings potted on and stopped when about 4 in. high to induce bushiness and brought under glass, temperature 55 to 60°F. (13 to 16°C.), in September or October.


Salvia splendens is the scarlet sage, a beautiful Brazilian with spikes of fiery red, sage-like flowers and equally vivid bracts on branching 2 to 3-ft. Stems and smooth, oval, pointed leaves. For window boxes Dwarf Gem (9 in.) or Fireball (12 to 15 in.) are ideal. There are also white and dull purple varieties, but these are less arresting than the scarlets.

Although perennial the plants should be treated as half-hardy annuals. The seed germinates in eight days and seedlings should have the tops pinched out when 3 to 4 in. high. They require light but rich soil with plenty of moisture and full sun.


Dwarf nasturtiums (Tropaeolum majus) make good container plants for sun or light shade as they bloom continuously all summer with variously coloured, helmet-shaped flowers and round silvery leaves. Seedsmen recognize and offer various races, particularly the varieties nanum, Tom Thumb and the lovely climbing Gleam Hybrids. These have double flowers of orange, primrose, scarlet, pink or salmon, some with dark foliage and another called Alaska has cream-splashed variegated leaves.

The climbing Gleam Hybrids can also be trained up trellises behind window boxes or in tubs to disguise dustbins and similar ugly features. Blackfly may attack the plants, but soon succumb to derris spray.

Nasturtium seed germinates in about ten days and can either be sown where it is to flower or grown under glass and put outside when there is no more risk of frost. The flowers are faintly scented and the crushed foliage has a pungent smell. Both flowers and leaves can be eaten in salads and the seeds used as a substitute for capers.

Other plants to try in containers are the trailing lobelia, silver-edged centaureas, wallflowers, polyanthus and forget-me-nots and poppies, ageratum, calendulas and calceolarias.

Sorry, comments are closed for this post.