Perfect trees in containers

POTTED ORCHARD: Ballerina apples, left, and a nectarine tree.
POTTED ORCHARD: Ballerina apples, left, and a nectarine tree.

If space is limited, growing fruit in containers may be an option.

And with careful selection, it's possible to grow a range of fruit trees, including apples, apricots, pears, peaches, nectarines and berries such as blueberries and strawberries. The trick is to source dwarf or compact trees and the right pot for the job.

Many new releases are now grown on dwarfing rootstock, which allows urban gardeners to grow fruit trees in their backyards or in containers. Check the label before buying to ensure you're getting what you want. For example, an apple tree may be grafted on to various rootstocks. You'll see the cultivar name, with the rootstock printed beside it, such as ‘Ariane', M.9.

M.9 is a dwarf apple rootstock, as is M.26. Both grow between two metres and 3m high.

MM106 is a semi-dwarf apple rootstock, growing about 4.5m high, while M.27 is a super dwarf apple rootstock, often used for apple stepovers (espaliered at knee level so that you can literally step over it). Then we get to the taller growing trees. ‘Northern Spy' grows 3-5m high and is particularly suited to heavy clay soils. M.798 grows 4-6m high. So it's the trees with the dwarfing rootstock that you would look for.

In recent years ‘Ballerina' columnar apple trees have become popular. They grow vertically. They have no side stems, bearing their fruit on short spurs close to the trunk. If a side branch does appear, it's easy enough to prune it out.

Fully mature, these plants may grow up to 4m high (that's when planted in the garden), but because they only reach 30cm across, they're perfect for containers or planted out in small gardens.

A compact citrus tree might be grafted on to a dwarfing rootstock such as ‘Flying Dragon' and a pear on to the dwarfing rootstock ‘Quince C', so this is what you should look for. Any fig tree, on the other hand, grows well in a container. Fig trees don't mind, and in some cases grow and produce better, when their roots are restricted.

Look for a compact nectarine such as ‘Flavourzee', ‘Garden Delight' or ‘Nectar Babe'. The latter two have a low chilling requirement, making them ideal for warmer areas, though they grow well in all parts of the country.

Last year I planted the new-release nectarine ‘Mabel', which is also suitable for all areas of the country. It's truly unique with its ornamental red leaves and looks heavenly in the garden. It grows to about 3.5m, though in a container the plant would grow slightly shorter.

There are several dwarf peaches to choose from, including the self- fertile ‘Pixzee', the pink-blossomed ‘Honey Babe', rosy-red blossomed ‘Rose Chiffon', and the freestone varieties, ‘Bonanza' and ‘Garden Lady'.

And in the apricot range, there's the super compact ‘Aprigold' (grows up to 1.8m) and ‘Golden Glow' (1.5m) - or choose a double grafted dwarf form where both varieties have been grafted on to the same tree.

There are nut trees too that are suitable for growing in containers. The ‘Garden Prince' almond is a dwarf form with pretty soft pink blossoms followed by medium-sized nuts. It's self-fertile and grows up to 2.5-3m high.

As for containers, plastic pots are better than clay pots. Clay ones dry out much faster. One of the key factors for success with container-grown trees is to keep them well-watered and a plastic container retains moisture better.

Clay pots are also much heavier, and as fruit trees are best repotted every two to three years, a lightweight pot, such as plastic, is much more manageable.

A third reason to use plastic pots is because clay pots, being porous, frequently build up salt deposits on their surfaces. As the salts from fertilisers dissolve in water they move about the clay. When the pot dries they form a crusty layer on the surface. You can see this easily when the surface turns white. You can, of course, wash the salts off when you're repotting (soak in 250ml of vinegar to 750ml of water), though that's just one more job to do.

Another point against porous pots is that they can harbour diseases over winter or even when in storage. Soak pots overnight with a solution of 250ml bleach to 4 litres water.

When it comes to size, the pot doesn't have to be enormous. Dwarf trees can initially be planted in containers about 45cm in diameter, but they will need repotting after two to three years. Repot into a container that's one size up. Do this until you have a pot that's about 60cm in diameter. After that, root-prune every second year, replacing 30 per cent of the potting mix at the same time, using a good-quality potting mix that contains slow-release fertiliser and water retaining crystals. If it doesn't contain the latter, add it in yourself. Since you're only replacing 30 per cent of the potting mix, a monthly liquid feed is ideal too.

By picking the right tree and pot, it's easy to grow a small containerised orchard.

Just don't forget to water. Trees in containers need more water than those in the ground.

The Southland Times