Gardening in Containers

There are, of course, many other reasons why the popularity of this form of gardening is growing. Garden centres now offer a much bigger range of attractive tubs, pots, troughs, hanging baskets, vertical garden kits and window boxes, and an even greater variety of plants to grow in them.

Moreover, there are new, efficient potting mixtures these days which greatly reduce the chances of failure, and plant breeders have developed plants more suitable for tub culture. However, the two outstanding advantages of gardening in containers are that they are portable and that almost any plant can be grown in them – flowering annuals, bulbs, ferns, creepers, herbs, shrubs and trees. There are even specially bred compact forms of fruiting plants for confined space.

Situation and Potting Mix

To be a successful container gardener you must choose the right plant for your situation. Balconies are often windy, so anything you plant should be able to stand up to the breezes. The amount of sunlight is very important and will also influence your choice of plants. Sun-loving plants – which includes vegetables – need at least four to five hours of sunlight each day to grow successfully, so check the amount of sunshine before spending money on plants that may not be suitable. Containers must have free drainage, otherwise, your plants will drown. Most pots and tubs have one or several drainage holes 1–2 cm in diameter.

Ordinary garden soil is unsuitable for pot culture because it does not drain well and tends to set hard. Plant up with a potting mix as they are open, porous mixes which have the added advantage of being free from weed seeds, soil pests and plant diseases. For a top-quality potting mix, try Yates Premium Potting Mix. For plants that need a specialised growing media, specialty potting mixes are also available, like Yates Thrive Orchid Potting Mix and Yates Thrive Cacti & Succulent Potting Mix.

When potting up most plants, don’t be tempted to put a small plant into a large pot with the idea of saving yourself some work. Plants do not thrive in over-large containers – some even prefer to be crowded. It is best to move a plant into a slightly larger pot when the previous one fills with roots.

Watering and Feeding

Whatever you decide to grow in your pots, remember that container-grown plants have a restricted root system and cannot forage for moisture as they would do in the open garden. On hot summer days, daily watering may be needed – perhaps twice a day if the plants are in full sunlight. Always water deeply and thoroughly – not just a sprinkle. Use a water-breaker or a watering wand rather than a hose nozzle. A water-breaker delivers a large volume of water gently onto the potting mix and causes minimum disturbance. When potting, leave a margin between the soil level and the rim of the container. When watering, fill this space slowly with water until it weeps out of the drainage holes. A mulch of grass clippings, compost, coarse gravel, pebbles or pine bark helps to reduce evaporation and cools the surface soil. Good drainage and frequent watering can also mean loss of plant nutrients. Regular, small amounts of fertiliser are needed to keep plants growing strongly.

Always apply fertilisers to moist soil to avoid burning young roots. A liquid fertiliser, like Yates Thrive Natural Fish & Seaweed+ Plant Food Concentrate, is suitable for regular liquid feeds. Slow acting fertilisers, like Yates Dynamic Lifter Organic Plant Food or controlled release fertilisers like the Yates Acticote range are also suitable to provide nutrients over a long period. Whatever fertiliser you choose, always use it according to the manufacturer’s directions. Too much fertiliser for potted plants can be disastrous, especially if the mix becomes dry. 

Pests and Diseases

Container-grown plants are not immune to attack by pests and diseases. Grubs, bugs, blights and mildews must always be guarded against. A few plants on a balcony can often be kept clear of caterpillars, snails and other leaf-eating pests by picking them off by hand or spraying with low-toxic insect sprays that are suitable for controlling pests of potted and indoor plants. Yates Nature's Way Organic Citrus, Vegie & Ornamental Spray Ready to Use is ideal to control most bugs on edible and ornamental plants. A few pellets of Yates Blitzem Slug & Snail Pellets around the base of potted plants will help control snails and slugs.

Favourite Shrubs for Tubs

• Camellias and azaleas with all-year-round foliage and exquisite flowers in season make excellent tub specimens. They do best in partial shade or filtered sunlight. They prefer an acidic potting mix, so proprietary mixes that are marked as being suitable for azaleas and camellias are the best choice for growing these plants successfully. Growing these acid-loving plants in tubs is a good solution if your garden soil is alkaline, which it may well be in some districts.
• Hydrangeas make magnificent tub plants for shady situations, although they do look rather bare in winter. They give a wonderful flower display in summer and can be brought indoors when flowering. Flower colour depends on whether the mix is acid or alkaline – blue in acid soil, pink in alkaline. If you want your hydrangeas to be a particular colour, grow them in a tub and treat the mix accordingly.  
• Fuchsias – and there are dozens of varieties – are dependable flowering shrubs for tubs, pots or hanging baskets in cool and temperate climates. Flowers in white, pink, red and purple are produced over a long period.
• Gardenias, with handsome glossy leaves and waxy, white, fragrant flowers, make good tub specimens. Gardenias prefer full sun or half sun in a warm, sheltered spot. In the right position (especially in warm climates) some varieties of gardenias will flower from spring to autumn.
• Daphne is another neat, evergreen shrub with exquisitely perfumed pink, red or mauve flowers in late winter and spring. Plants need good drainage and are often more reliable in a large pot or tub than in the open garden. They prefer morning sun but shade for the rest of the day.
• Geraniums will provide a bright patch of colour on a sunny terrace or patio. Grow them in tubs, large pots or window boxes; with plenty of sun they will flower from early spring to late autumn. The ivy-leaf trailing varieties are ideal for hanging baskets.
• Bougainvillaea is another sun-lover, especially for warm, northern climates, and dwarf varieties are now readily available. These are best for containers and give a magnificent, long-lasting display of flower bracts.
• Citrus trees are both ornamental and useful tub plants for outdoor living areas. The smaller citrus trees like cumquats and limes are easy to grow in tubs, but potted lemons, oranges and mandarins may need pruning to keep them within bounds. Choose citrus grafted onto dwarfing rootstocks.
• Japanese bamboo, also known as nandina, with its lacy foliage, makes a good container plant and can be kept in bounds by pruning. True bamboo, which belongs to the grass family, gives a great vertical contrast effect, but only dwarf varieties up to 2–3 m tall should be chosen.

Roses

Roses do well in tubs and pots and they are easy to grow, though obviously the miniature varieties and small floribundas will perform best. They are not fussy about climate and can withstand hot summers as well as freezing winters – provided you don’t let the container dry out. Full-sized roses need a pot at least 50cm or more in diameter to allow room for the roots to develop properly. Fertilise with slow acting fertiliser, like Yates Thrive Rose & Flower Granular Plant Food in early spring, as new growth begins, and again in early autumn.

Your display will last longer if you keep removing dead flower heads to encourage the formation of new buds. Don't allow rose hips (fruits) to develop because they drain energy from the plant and inhibit the growth of more flowers.