In recent years there has been a great surge of interest in growing plants in boxes, pots, hanging baskets and other containers, with some houses and commercial premises a mass of flowers from May to October. Modern commercial buildings are often designed with integral planting in boxes and on balconies, usually of shrubs, climbers and other perennial species. ‘Green roofs’ can include all sorts of planting from mosses, succulents and turfs, through to elaborate roof gardens. See Building Green, Johnston, Jacklyn and newton, John (London Ecology Unit).
There are many books available on all aspects of container gardening, along with a wide range of containers and accessories, and keen gardeners will need little prompting to experiment with all sorts of planting ideas. For beginner gardeners, it’s best to start with reliable summer annuals or spring bulbs. Many annuals will attract bees and other insects, as well as providing flowering colour. To avoid too much expense, various recycled containers can be used, and many plants can be grown from seed. It’s easier to produce a colourful and satisfying display during the summer, rather than try to keep containers going year- round. During the winter, the containers themselves together with the dying foliage, though not particularly attractive, can provide cover for a range of ‘mini-beasts’, amphibians or small mammals.
Containers
Anything that is reasonably sturdy and waterproof can be used, provided there is drainage at the bottom. Any plastic container, from ice-cream container upwards can be used. Make holes in the bottom with a skewer heated in a flame, or for thicker containers, with a drill. Cut-down jerricans or other containers are very durable, but wash out carefully to remove traces of chemicals. Plastic containers can be painted as required. Old paint tins or other metal containers are also suitable. Old sinks, chimney pots, water tanks and other scrap building materials can be used. Containers made out of scrap wood can be lined with thick plastic to retain water and prolong the life of the wood. In addition, bubble plastic can be used as an insulating liner to protect roots from frost damage.
Generally the larger the container the better, but be prepared for the amount of compost which will be needed to fill it. Expanded polystyrene can be used as a bottom layer to improve drainage without increasing the weight.A container about the volume of a large bucket is reasonable for the average person to move. Any larger than this, and you will need to fill the container in situ. Supports for containers, and fixings for hanging containers must be sufficient to take the weight. Remember that you must have access for daily watering in summer for most types of planting, or otherwise fit an automatic watering system, available from large garden centres.
Compost
Avoid buying peat-based composts, because of the destruction of natural habitat caused by the peat industry.
For bulbs or annuals, coir or other peat-free substitutes are suitable. For long-term planting of shrubs or climbers, a soil-based ‘John Innes No. 3’ compost is essential. Ordinary garden soil is not usually suitable for any container planting, and will only give disappointing results because it will harden to a solid mass, uninviting to plant roots. Home-made compost from a compost heap may be suitable. It is likely to contain a lot of weed seeds, but most of these can be prevented from germinating by covering with a top layer, about 50mm deep, of sterile commercial compost.
Planting
A huge range of plants are available from March onwards for planting in containers. Protect from late frosts as necessary. Purchasing plants is expensive, and you will usually want to grow at least some from seed. For beginners, the following is suggested.
Start with easy to grow annuals, which can be sown into small pots or margarine containers of compost, put in a plastic bag and germinated indoors. Grow them on by a sunny window until they are big enough to plant out into the containers. Alternatively, they can be sown directly into the container, although frequent care will still be needed. Large seeded annuals such as pot marigold (Calendula), nasturtium and sunflower are the easiest to grow. Other suitable species include cornflowers, godetia, poppy, Virginian stock, candytuft, corn cockle, love-in-a-mist (Nigella) and poached egg plant (Limnanthes douglasii). If you have a sunny porch or conservatory, it’s possible to germinate other species from February onwards in seed trays or pots, for planting out. These ‘half-hardy annual’ species such as alyssum, antirrhinum, tobacco plant, heliotrope and many others are colourful and attractive to insects. However, raising them successfully requires light, warmth and daily care, and if you don’t have suitable facilities it’s best to buy them as ‘bedding plants’ in April or May. For straightforward colour, geraniums, busy lizzies and petunias are the best, but these must be sown very early in the spring and then grown on in a greenhouse.
Care
Hanging baskets and small containers will need watering once a day in hot weather. Remove dead flowers during the summer to encourage further flowering, and then leave the final seed heads to provide bird and small mammal food during autumn and winter.
Regular feeding will encourage stronger growth and more flowers. Slow-release granules or sticks, inserted into the container at planting, are an easy but rather expensive method. Weekly feeding with a dissolved powder feed is cheaper and more effective. Organic feeds can be made from nettles and other composted plants, but are rather smelly to store and use.
When the plants die down in autumn, you can either simply leave the containers where they are until spring to provide cover for ‘mini-beasts’, or clear them away if tidiness is important. Small containers will be a mass of roots, and should simply be tipped out onto a compost heap. With large containers, dig away all the rooted layer in spring, and top up with fresh compost.
For spring flowers, plant daffodils, tulips, primroses, pansies or similar in autumn.
Herbaceous perennials, rockery plants and herbs can be grown in containers for two or three years, by which time they will need dividing or repotting. They don’t provide such a long flowering season as annuals, but the flowers are often attractive to bees and butterflies, and the foliage is attractive. One small plant of an herbaceous perennial will grow to fill a pot and can be divided to make many new plants. Ice plant (Sedum spectabile), cat-mint, dwarf Michaelmas daisies, lady’s mantle (Alchemilla mollis) and dwarf golden rod are recommended as a start.
With suitable containers, good composts, feeding and care, almost any type of plant can be grown in a container, including vegetables, herbs, fruit, shrubs, climbers and small trees. Gardening is a great interest and therapy for many people, and container gardening brings it within the reach of those without a plot of ground.
