Potted fruit

Jim Arbury describes container cultivation of some popular hardy fruits, based on techniques at RHS Garden Wisley, and suggests the best cultivars

The sight of ripening apples, peaches, pears and other hardy fruits thriving on the patio of the Enthusiast's Fruit Garden at Wisley hopefully encourages visitors to grow fruit trees in pots. Pot cultivation enables fruit to be grown wherever desired, in the best aspect. It is particularly useful to people without a garden, enabling fruit trees to be grown on paved areas and courtyards.

Many are quite ornamental, especially when in blossom. Container growing also allows less hardy fruit, such as peaches and nectarines, to be easily sheltered in winter. They can have their flowers protected from frost in a cold glasshouse, and can be moved outside again when fruits have set. Compared to open-ground growing however, pot-grown trees will not yield such a great quantity of fruits, and require more care and attention.

Cultivation of apples and pears

Place the trees in a sunny aspect, sheltered from wind (avoid places prone to wind eddying). Turn the pots regularly, especially if they are in a corner, to ensure even growth and ripening of wood and fruits.

During the growing season, watering may well be needed once or twice per day. Water copiously when the surface of the compost is dry, filling up to the rim. In winter watering will be less frequent, but never allow the compost to dry out completely.

Liquid feed weekly in spring and summer, using a recognised tomato fertiliser. Its high-potassium content will promote fruiting. About once a month alternate this with a general-purpose liquid fertiliser to ensure adequate nitrogen, because using tomato fertiliser alone can lead to a deficiency of this major nutrient. The alternative to liquid feeding is to place slow-release tablets such as Osmocote® in the compost, according to the manufacturer's instructions.

Topdress annually in spring with a layer of fresh compost, first scraping away about 5cm (2in) depth of the old growing medium. It is important to repot trees every two to three years in order to give them a refreshed environment in which to thrive. Remove loose material from the pot and cut back any thick, thong-like roots if the tree is becoming pot-bound.

Potting

Any type of outdoor container is suitable for fruit trees provided it is well drained, with a hole in its base and has a depth at least equal to the diameter. Start off with a container about 30cm (12in) in diameter - slightly larger than the rootball of the young tree.

Pot on to a larger size before trees become pot-bound. A maximum pot size of 45cm (18in) diameter is recommended - any larger and it will be difficult to move the container and to repot. Even a 45cm (18in) container needs two people to lift it. Large terracotta pots can be extremely heavy and more brittle, so plastic might be preferred.

Pot new trees at any time during the dormant winter months, making sure the graft union is above the compost surface. Pot on or repot established trees in late winter. Use a soil-based compost for stability and nutrient retention, such as John Innes potting compost No.2 or No.3. Depending on the size of container, leave a gap of 2.5-5cm (1-2in) between the compost surface and the rim of the pot, in order to allow plenty of room to apply adequate water.

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