Growing in containers

Gardening on balconies

A few considerations
Pots and containers
Maximising your growing area
Choosing plants
Planting
Aftercare

A few considerations

Most balconies offer little protection from the elements, lacking the screens and buffers provided by trees, shrubs, hedges and fences in ground level gardens. Strong winds, and the air turbulence often created between tall buildings can cause havoc in high-level gardens.

Various types of trellis or netting can be used as wind-breaks to make the balcony more pleasant to sit out on and to provide support for climbing plants. Choose a strong net in the smallest mesh size available, as the larger the mesh the less effective it is as a wind-break. Resist the temptation to build a solid barrier which could cause severe air turbulence and damage the plants almost as badly as direct wind. Remember too, to fix the netting securely, especially if you intend growing plants up it. The extra wind resistance produced by the foliage could make your wind-break into a 'sail' which could rip off if not firmly fitted.

Sunlight could be restricted on a balcony, in some cases with sunlight only striking the balcony from one side. To increase the light intensity and to provide a more even distribution of light, paint the walls on all sides of the balcony matt white. This will also set off the plants to excellent effect.

If your balcony is overshadowed by the balcony above, grow the sun-loving plants such as geraniums, nasturtiums, tomatoes and peppers at the front, and place shade tolerant ones such as foxglove, rhododendron, ivy, periwinkle and fern nearer the back wall.

It is unlikely that you will want to transport too many tons of soil up to your aerial garden, but it might be an idea to seek advice on the amount of weight your balcony can take and keep a close eye on the materials used for containers and the quantity and type of compost used. (Soil-less composts are lighter than soil-based ones, but dry out more quickly).

Pots and containers

The most suitable size for a pot or container depends on the space available and the plants you want to grow. The main disadvantages in using small containers are that they dry out quickly and the nutrients in the compost are soon used up. Some plants, such as stonecrops and houseleeks, grow quite happily in small pockets of soil and seem no worse for frequent drying out, but these are exceptions. Most plants soon die if allowed to become completely dry, or at best become more prone to attack by pests and diseases. Large containers have the disadvantage of weight. The choice of container material is important, with concrete, reconstituted stone and cast-iron being among the heaviest of those readily available, and among the dearest to buy.

Plastic and fibreglass are cheaper and lighter, and are also available in the greatest varieties of shapes and colours. Being impermeable, soil dries out more slowly in these as well. However, there is more danger of waterlogging in an impermeable container - a disadvantage shared by metal or glazed pottery - especially if they catch drips from the balcony above. A less permanent, but very light choice could be found among a range of polystyrene containers. For a mellow, traditional look without too much weight, wood or terracotta is probably best.

Whatever the material or size, all containers must have drainage holes in the bottom so that excess water can escape, and the soil does not remain too wet for too long. Most plant containers have these holes when you buy them but some only have marks indicating where they should be made. Make sure that the holes are big enough, and with all large vessels it is a good idea to put in some pebbles or crocks before the compost. This is particularly important if you use John Innes compost or grow perennial plants in the same pot year after year. Dripping water can be a nuisance to the people on the balcony beneath, so use saucers under your pots wherever you can, and never place pots where they can be knocked or blown into the street below.

Maximising your growing area

Climbing plants can be planted in pots and containers on the balcony floor and will cover a support quite quicklv to produce a vertical garden. Ivies and honeysuckles are happy in shade and will do well next to a wall, even under a deep overhang. Nasturtiums, sweet peas, morning glory, runner beans and some types of culinary pea will give rapid growth for just one season.

The walls of your balcony can also be put to good effect with wall-baskets and strong shelves to support flower pots. Make sure that they are firmly attached, using screws and rawlplugs rather than masonry nails. These raised containers are suitable for trailing bedding plants such as geraniums, petunias and lobelia, or for the smaller fruiting (cherry) tomatoes. Gourds, peas and french beans can also do remarkably well in these containers if they get enough fight. Traditional hanging baskets can be effectively planted too, providing spectacular curtains of colour, until well into the autumn. Fix the hanging baskets onto a pulley system for ease of maintenance.

The railings of the balcony can act as extremely useful supports for climbing plants. A row of troughs or 'grow-bags' along their base will provide sufficient growing medium for an excellent crop of tomatoes or ridge (outdoor) cucumbers. Peas and runner beans will also do well in this position, as will a vast array of sun-loving flowering plants.

Choosing plants

When buying plants choose only those which are strong-growing and bushy. Do not be tempted to buy those offered for sale too early in the year as they will be killed by cold winds or have their tender leaves torn to shreds. It is unwise to plant half-hardy material before May unless the balcony is very sheltered. It is worth the extra expense of buying perennial bedding plants such as geraniums and dahlias which have been grown singly in pots. Inspect perennial plants such as climbers to ensure that they are not damaged or diseased, and have no pests on them.

Planting

If a plant with dry compost around its roots is planted out even into moist surroundings the chances are that the compost will always remain dry and the plant will not grow as it should. Always water or soak your plants before planting them into a larger container.
Make the hole in the compost large enough to take the roots of the plant easily. Allow the roots room to spread out comfortably.
When filling the hole, shake the plant gently up and down so that the compost falls between the roots. Firm the compost with your knuckles so that the wind doesn't rock the plant about. Try to keep the plants at the same level as they were in their boxes or pots, as a change in soil level could cause the stems to rot. When planting has been completed, water the plants thoroughly using a fine rose on your watering can. This will not only moisten the compost but will settle the plants in.
One way of achieving a succession of colour in the containers is to fill them with moist peat and then plunge the plants, still in their pots, into this. As the flowers fade or the plants die the pots can be removed and replaced with others.

Aftercare

The function of a flower is to produce fruit and seeds. In order to prolong the flowering period of decorative plants, dead-heading is an essential regular activity. Weeding should not be a problem if sterilised compost is used, but 'feeding' the plants with correctly diluted liquid fertiliser will be necessary from six weeks after planting.

It is normally necessary to feed plants in containers once or twice a week once established. Watering may well be necessary every day in the summer months. The best time to water is in the evening so that the plants will have the benefit of the water all night before the sun dries them out again. Perennial plants, including shrubs will also need watering during the winter. If plant pots are resting on saucers, make sure that they are not standing in water for long periods, as this can kill roots by restricting oxygen availability.