Peach

About

A peach tree in a British garden will get peach leaf curl every spring unless you keep the rain off it in late winter.

The fungus, Taphrina deformans, is spread by spores in rain splash from January to May, and it infects the buds as they open. The leaves emerge red, blistered, thickened and puckered, then yellow and drop, and a tree that defoliates twice in a row is badly weakened and crops nothing.

There is no useful spray available to gardeners in Britain. The control is physical. Build a polythene shelter over a wall-trained tree from January to late May, open at the sides for air movement, so the rain never reaches the buds. That single measure is the difference between a healthy tree and an annual disaster.

The second problem is the flowering time. Peaches blossom in February, weeks before any pollinating insect is reliably flying and squarely inside the frost season. That means hand pollinating with a soft brush on warm days, and fleecing the tree whenever frost is forecast.

Given a warm south-facing wall, a rain shelter and a paintbrush, peaches crop well in southern Britain and the fruit is worth every bit of the trouble.

Nectarines are the same species with a recessive gene for smooth skin, they are slightly less hardy, and everything here applies to them.

Appearance and character

A deciduous tree reaching 3 to 5 m as a bush, and trained flat as a fan against a wall in most British gardens.

Leaves are narrow and lance-shaped, 8 to 15 cm long, glossy mid-green, finely toothed and often folded along the midrib.

Blossom opens in February and March, before the leaves, 2.5 to 3.5 cm across, deep pink to rose, borne singly or in pairs along the previous year’s wood.

Fruit ripens from July to September depending on cultivar, round, 5 to 8 cm across, with velvety skin in yellow flushed red, and yellow or white flesh around a deeply pitted stone.

Nectarines have smooth skin and are otherwise identical.

Freestone cultivars release the stone cleanly and clingstone cultivars do not.

Peaches fruit on wood made the previous summer, which governs the whole pruning approach.

Rootstocks control size. St Julien A gives a tree of 3 to 4 m, and Pixy is more dwarfing and suits a container.

‘Peregrine’ and ‘Rochester’ are the standard British outdoor cultivars, and ‘Avalon Pride’ carries useful resistance to peach leaf curl.

Where it is from

North-west China, where it has been cultivated for at least four thousand years and where the wild relatives grow.

The species name records a mistaken belief that it came from Persia, which was a staging post on its westward journey rather than its origin.

It reached the Mediterranean by Roman times and Britain by the sixteenth century, where it was grown against heated walls in the great kitchen gardens of the eighteenth and nineteenth centuries.

The Victorian walled garden is the context in which peaches were grown well in Britain, with south-facing brick walls, glass lean-tos and heating flues doing what the climate does not.

Peach has deep cultural weight in China, where the fruit symbolises longevity and immortality and appears throughout art and mythology.

Peach leaf curl has been recognised as a disease of the crop since the eighteenth century, and the copper-based sprays that once controlled it are no longer available to gardeners in Britain.

‘Avalon Pride’ was found as a chance seedling in Washington State in the 1970s and carries genuine partial resistance to leaf curl, which makes it the sensible choice for anyone unwilling to build a shelter.

How it grows

Choose a warm sheltered south or south-west facing wall. This is not a tree for an open position in most of Britain.

Plant a fan-trained tree in autumn or early spring, 20 to 25 cm out from the wall, leaning slightly towards it.

Fix horizontal wires 15 cm apart on the wall and tie the fan ribs in.

Improve the soil at planting with compost and grit, and aim for a deep free-draining slightly acid to neutral soil.

Build a rain shelter over the tree from January to late May. A polythene sheet on a simple timber frame, projecting 45 cm from the wall and open at both ends, keeps the rain off the buds and prevents peach leaf curl. Take it down at the end of May.

Hand pollinate. Peaches flower in February when almost no insects are flying. Go over the open flowers with a soft artist’s brush or a rabbit’s tail every day or two on a warm dry afternoon, transferring pollen from flower to flower.

Fleece the tree whenever frost is forecast during flowering, and remove the fleece by day so insects can reach it.

Thin the fruit in two stages. Thin first when the fruitlets are the size of a hazelnut, to 10 cm apart, and again when they are walnut sized, to 20 to 25 cm apart. This is what produces fruit worth eating rather than a heavy crop of small ones.

Water regularly and generously, since the soil at the foot of a wall is in permanent rain shadow.

Mulch every spring with compost or well-rotted manure.

Prune in spring and summer, never in winter. Prunus is susceptible to silver leaf and bacterial canker, both of which enter winter pruning wounds.

Prune on the replacement system. Peaches fruit on last summer’s wood, so each spring select a replacement shoot at the base of every fruiting shoot, remove competing shoots, and after harvest cut the shoot that has fruited back to the replacement.

Tie in the new growth as it extends.

Harvest when the fruit gives slightly to gentle pressure at the stalk end and comes away with a gentle lift and twist.

Expect a tree to crop for fifteen to twenty years.

Through the seasons

Winter is when the rain shelter goes up in January, and the tree is dormant and should not be pruned.

Spring flowers in February and March under the shelter, is hand pollinated and fleeced against frost, and pruning starts once growth begins.

Summer swells and ripens the fruit from July, and the shelter comes down at the end of May. Thinning and tying in happen now.

Autumn finishes the harvest, and the leaves fall. This is planting season.

Care difficulty

Difficult. Peaches are among the more demanding fruit in a British garden, and none of the difficulty is in the growing.

Peach leaf curl needs a physical rain shelter for five months of the year, or a resistant cultivar.

February blossom needs hand pollination and frost protection.

Pruning has to be done in the growing season on the replacement system, which is more involved than most fruit.

Watering a wall-trained tree in rain shadow is a real commitment.

The reward is fruit that is nothing like anything you can buy, from a tree that occupies a wall rather than a plot.

Watering

Water regularly and generously through the growing season, particularly from fruit set to harvest.

The strip at the foot of a wall gets almost no rain, so a wall-trained peach needs watering even in a wet summer.

A rain shelter makes the soil beneath it drier still, and the tree needs watering under it.

Give a thorough weekly soak in dry weather rather than a daily sprinkle.

Mulch every spring to conserve moisture, keeping it clear of the trunk.

Irregular watering causes split stone and fruit drop.

Warning signs, diseases and pests

Leaves emerging red, thickened, blistered and puckered in spring, then yellowing and dropping, is peach leaf curl. Pick off and burn affected leaves, feed and water the tree to help it produce a second flush, and put a rain shelter up from January next year. There is no effective spray available to gardeners in Britain, and ‘Avalon Pride’ is partially resistant.

No fruit set despite good blossom is a lack of pollination, frost, or both. Hand pollinate with a soft brush and fleece the tree when frost is forecast.

Fruit rotting on the tree with concentric rings of buff pustules is brown rot. Remove and destroy affected fruit and any mummified fruit hanging on over winter.

Silvery sheen on the foliage with a dark stain inside cut wood is silver leaf, entering pruning wounds. Prune only in the growing season.

Sunken oozing patches on the bark with gumming and dieback is bacterial canker. Cut out affected wood in summer and prune only in the growing season.

Fruit splitting at the stone end, with a hollow or split stone, is irregular watering. Water steadily.

Gum oozing from the trunk and branches is gummosis, which follows stress, damage or disease. Investigate the cause rather than treating the gum.

Red spider mite gives fine mottling and webbing under a rain shelter in hot dry conditions. Increase air movement and humidity.

Growing environment

Full sun against a warm sheltered south or south-west facing wall. An open position in Britain rarely works outside the mildest areas.

Deep, fertile, free-draining, slightly acid to neutral soil.

The tree is hardy and the February blossom is not, so frost during flowering is the limitation rather than winter cold.

Allow 3.5 to 4.5 m of wall for a fan on St Julien A rootstock.

It suits a south-facing house wall, a walled garden, a lean-to greenhouse, a conservatory or a large container on a dwarfing rootstock.

Grow it in a greenhouse or a large container moved under cover for the winter in a cold garden, which solves the leaf curl and the frost together.

Choose ‘Peregrine’ for flavour and ‘Rochester’ for reliability, and ‘Avalon Pride’ if you want partial leaf curl resistance without building a shelter.

Nectarines want a warmer position still and are best under glass in most of Britain.

Feeding

Feed in early spring with a general balanced fertiliser.

Feed again in early summer with a high-potash feed such as sulphate of potash, which supports fruiting and ripening.

Mulch every spring with compost or well-rotted manure, keeping it clear of the trunk.

Feed generously after an attack of leaf curl, which helps the tree produce a replacement flush of leaves.

Avoid high-nitrogen feeds, which produce soft growth that canker enters more easily.

Container-grown trees need liquid feeding through the growing season and repotting every two or three years.

Troubleshooting

The leaves came out red, blistered and puckered. Peach leaf curl, spread by rain splash onto the opening buds. Pick off and burn the affected leaves, feed and water the tree, and put a polythene rain shelter over it from January to late May next year.

Is there a spray for leaf curl? No effective one is available to gardeners in Britain. The control is keeping the rain off the buds from January to May, or growing the partially resistant ‘Avalon Pride’.

It flowered well and set no fruit. No pollinating insects are flying in February, and frost may have destroyed the flowers. Hand pollinate daily with a soft brush on warm afternoons, and fleece the tree when frost is forecast.

When do I prune it? In spring and summer, never in winter. Winter cuts let in silver leaf and bacterial canker. Prune on the replacement system, cutting each fruited shoot back to a new shoot after harvest.

Should I thin the fruit? Yes, in two stages. Thin to 10 cm apart at hazelnut size and to 20 to 25 cm at walnut size. Unthinned trees produce a lot of small poor fruit.

The fruit split at the stone. Irregular watering. Keep the soil evenly moist, which is harder than it sounds at the foot of a wall under a rain shelter.

Can I grow one in a pot? Yes, on Pixy rootstock in a large container, which lets you move it under cover in winter and solves the leaf curl and frost problems together.

Are nectarines different? They are the same species with smooth skin, slightly less hardy, and best under glass in most of Britain. Everything else applies equally.

Can I eat the kernel inside the stone? No. It contains amygdalin, which releases cyanide when crushed and chewed. Never crack peach stones for the kernel.