Window Boxes

For the town dweller who would like to have a garden but lacks the space, a window-box provides a solution and the opportunity to indulge in some of the pleasures of gardening while being spared many of its problems. Window-box gardening is a compromise between the indoor pot plant and the outdoor garden border, but it still requires skill and care to bring plants to perfection. This is an instructive and entertaining form of gardening, resulting in a gay and colourful adornment for a house.-


The size and shape of the windows, the dimension of the sills, and the architectural style of the house itself will determine the type of window-box to use. Though available with handles, window-boxes are best regarded as a permanent fixture.

Red cedar, teak, oak and elm are the best woods for window-boxes, in that order, while other suitable materials are concrete, cement, artificial stone, metal or plastic. An artificial stone box can be quite effective, especially if the outer face is moulded to accord with the design of the house front, and some metal ones are most decorative as well as practical.

Before painting any of these surfaces, apply an initial coat of sealing or priming paint. Make sure that the material is quite dry and free from dust before painting. Wooden boxes require three coats of paint a year and the inside of the box should be treated with a preservative like green Cuprinol: about 3/4 pt. Will be sufficient for a box 3 ft. long and 9 in. deep. This is harmless to plant-roots once it has dried, and will give good protection for at least three or four years.

Better still, line the box with light metal or zinc, which will both prolong the life of the wood and retain moisture in the soil.

Stone and concrete boxes are generally available in standard patterns, from 2 to 4 ft. long, about 8 in. deep, 7-1/2 in. wide at the base and slightly wider at the top.


Place blocks of wood under the window-box to keep it clear of the sill and fix the box securely by driving wedges between the ends of the box and the side walls, or, better still, by attaching it with hooks to eyelets in the window frame.

If the box is hung under the window-sill or fixed on a wall, use stout wall-brackets attached to the wall by Rawl-plugs and 2-in. screws.

As an additional safeguard, a chain can be placed round the front of the box and fixed to hooks in the wall.

Use heavy-gauge galvanized straps to attach a box to a balcony railing, allowing one strap for each foot of box. If set on top of a brick wall or balcony, anchor the box with steel dowel pins set in the brickwork, again allowing one pin to every foot of box.


When the box is in position, spread a 2-in. layer of crocks in the bottom, placing one large piece over each drainage hole. Add a few pieces of charcoal to keep the soil sweet, and a layer of sphagnum moss, with some chopped turves and leaves. Then fill the box with really good soil, planting at the same time and finishing with the soil level and about l in. from the top.

Although a good compost can be made from a mixture of three parts loam, one part peat and one part sharp sand, all put through a fine sieve, it is easier, if a little more expensive, to use John Innes potting compost No. 2, which is available from horticultural sundriesmen. Never economize on the soil-filling for window-boxes.

Plant bulbs and other spring-flowering plants in September or October. When these have finished flowering they can immediately be replaced by summer-flowering plants.

When arranging the plants, make sure that the effect will be bright without being garish by aiming for harmonious effects rather than contrasts. Grey foliage always makes an effective foil for colour.


Since a window-box has only a limited soil capacity, is exposed to wind and sun, and often sheltered from rain by overhanging eaves and other projections, it tends to dry out rather quickly. Regular watering is therefore necessary. Although the exact frequency of watering depends on the aspect and position, a good soaking every three or four days, preferably in the evening, is generally sufficient to keep the soil moist. Do not flood the box. A dose of weak liquid manure once a fortnight during the summer is a good stimulant to growth. Always water before feeding, as liquid feed is harmful when applied to dry soil.

Stir the soil between the plants occasionally with a pointed stick or old kitchen fork to prevent the formation of a hard crust. When the plants are removed at the end of every spring and summer season, fork over the compost lightly, and give a dressing of fine bone meal or general fertilizer.

If possible, change the soil completely during the winter.


showing favoured aspects :

Ageratum, blue, June to September, south and west.

Alyssum, yellow or white, April and May, all except north.

Antirrhinum, usually yellow or red or pink, sometimes two-coloured, June to October, all except north.

Arabis, white, or pink, purple-blue, March to August, all except north.

Aubrieta, lilac to purple, April and May, all.

Auricula, multi-coloured, various combinations, March to May, all.

Begonia, white, pink, scarlet or yellow, July to September, all except north.

Bellis perennis (double daisy), white, pink or red, May and June, all.

Calceolaria, yellow, often marked with red or purple, June to September, south and west.

Calendula, orange or yellow, June onward, all except north.

Campanula carpatica, blue, June to August, south and west.

Canna, usually yellow and/or red, May to August, south and west.

Celosia cristata, dark red, June to September, south and west.

Centaurea nwschata (sweet sultan), white, yellow or purple, June to September, all except north. China aster, various, August to October, south and west.

Chionodoxa, blue, pink or white, March and April, all.

Chrysanthemum (pompon and Korean), various, August and September, all except north.

Coleus, white, blue, purple, October, south and west.

Convolvulus tricolor, blue, pink or white, July to September, south and west.

Crocus, usually white, blue, yellow, orange or purple, February to April, all.

Dahlia (single bedding varieties), usually scarlet or yellow, August and September, all except north.

Dianthus, usually red, pink or white, July to September, south and west. Fuchsia, reds, pinks and purple, July to September, south and west.

Gazania, yellow or orange, June to August, south and west.

Geranium, usually white, pink, red, purple or blue, June to August, all.

Heliotrope, blue or white, May to September, south and west.

Hyacinth, various, usually pink, white, blue or yellow, March and April, all except north.

Kochia, green or red, July and August, south and west.

Lobelia, blue or red, May to September, all.

Lysimachia nummularia (creeping Jenny), bright yellow, June to August, all.

Marguerite, white or yellow, June to August, all except north.

Mesembryanthemum, white, yellow, pink, red or purple, June to August, south and west.

Mignonette, white, June to September, all except north.

Myosotis palustris (forget-me-not), blue, white or pink, May and June, all.

Narcissus, white or yellow, March to May, all.

Nemesia, yellow, white, violet, red or blue, July to September, south and west.

Pansy, various, mixed, March to May, all.

Pelargonium, pink, red, purple, white, June to August, all except north.

Petunia, various, July to September, south and west.

Phlox drummondii, red or mauve, July onward, south and west.

Polyanthus, various, from white to deep purple, March to May, all.

Primrose, yellow, March and April, all.

Rose (miniature varieties), various, June to September, all.

Salvia Blaze of Fire, scarlet, July, south and west. S. patens, blue, September, south and west.

Saxifraga umbrosa (London pride), pink, May and June, all.

Scilla, blue or purple, March to May, all. Stock, white, pink, red or purple, July to September, all except north.

Sweet William, various, often two-coloured, May and June, all except north.

Tagetes, yellow or orange, July and August, all except north.

Tropaeohim majus (nasturtium), white, yellow, orange, red or purple, June to September, all except north.

Tulip, various, often yellow, pink, red or white, April and May, all except north.

Verbena hybrida, blue, purple, pink, red, yellow, or white, June to October, south and west.

Viola, usually white or purple, February to April, all.

Wallflower, white, red, yellow, orange or pink, April and May, all except north. Wallflower,

Siberian, orange, April to June, south and east. Zinnia, yellow, red, pink or purple, July to October, south and west.

Greenhouse plants such as calceolarias, cinerarias, and certain primulas including P. malacoides and P. sinensis, as well as dwarf Japanese azaleas, may be planted out in window-boxes in early May, just before they flower.

This practice cannot be relied upon to produce a display, however, as late frosts may damage the plants.


The following plants can be used to frame the window and its window-box:

Clematis jackmannii

C. Mme. Le Coultre

C. Nelly Moser

C. Royal Velours

Hedera helix (variegated forms)

Ipomoea (morning glory)

Jasminum nudiflorum lemicera japonica aureo-reliculata

Sweet pea

Vitis henryana

V. vinifera purpurea


In hospitable conditions, wallflowers planted out in the autumn will remain green throughout the winter. The only thoroughly reliable plants for a window-box in winter, however, are dwarf evergreen shrubs. Even these are not completely satisfactory, for few people can afford to discard these fairly expensive plants at the end of the winter; on the other hand, if they remain in the window-box, some of the spring and summer flower display will have to be sacrificed.

It is possible to compromise by mixing such spring bulbs as crocus, grape hyacinth, scilla, daffodil and tulip, with a few dwarf evergreen shrubs. These could include box, dwarf juniper and dwarf chamaecyparis. Erica cornea produces an excellent flowering display in late winter and early spring, especially the varieties King George, Vivelli, Springwood White, and Springwood Pink. Santolina chamaecyparissus (syn. S. incana) and S. neapolitana will thrive if facing south or west.


A window-box can combine beauty with utility if planted with a few herbs. They are not difficult to grow, and although less showy than bedding plants, they are nevertheless quite decorative.

Grow parsley from spring-sown seed, as well as lemon and common thyme, chives, mint and marjoram. The blue flowers of borage look most attractive hanging over the side of the box; balm and bergamot like moisture and a little shade.

16. February 2012 by Dave Pinkney
Categories: Featured Articles, Garden Management, Gardening Calendar | Tags: , , , | Comments Off on Window Boxes


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