Crab Apple Trees: The Most Useful Small Tree You Can Plant

A crab apple is the most useful small tree you can plant in a cool, wet climate, because it does four jobs at once. It pollinates every apple tree within bee range, it flowers for weeks in April for the bees, it holds small sour fruit into winter for the thrushes and fieldfares, and that same fruit makes the clearest, sharpest jelly in the cupboard. It stays under 6 or 8 m, grows in almost any soil, and is one of the cheapest trees we sell. This guide covers what a crab apple is, how to choose one, planting it bare-root, the little care it needs, and the jelly. It is written for Ireland and holds across the UK and northern Europe, where the crab apple is native too.

Short on time? A bare-root crab apple tree planted between November and March will flower in its second spring and start pollinating your apples the same year.

What a Crab Apple Is

The wild crab apple (Malus sylvestris) is a native tree of Irish and British hedgerows and woodland edges, with pink-white blossom in late April and hard, sour, yellow-green apples the size of a walnut in autumn. It is one of the ancestors of the orchard apple, which arrived in Europe from central Asia and crossed with the local crab along the way, and it is the tree that most apple rootstocks were once raised from. "Crab" is an old word for sour or crabbed, and the fruit lives up to it: a raw crab apple is too astringent for anyone, and that astringency is exactly what the kitchen wants.

The ornamental crab apples in gardens are mostly hybrids of the wild tree with Asian species, bred over the last 150 years for bigger flowers, coloured leaves and fruit in yellow, orange, red and purple that hangs on the bare branches into winter. Some of those are as good for jelly as the wild one and better for pollination, because they flower for longer. Both kinds are worth planting; which one depends on the job.

Four Jobs in One Tree

Pollination. Apples are self-incompatible: a tree cannot set fruit with its own pollen and needs a different variety flowering at the same time. A crab apple flowers for three or four weeks, longer than most eating apples, produces pollen in quantity, and is compatible with nearly every apple variety. That is why commercial orchards plant crab apples at the ends of the rows, and why a single crab apple in a garden lets one apple tree crop where it would otherwise flower and drop. Our apple trees guide explains why apples never come true and always need a partner.

Bees. The blossom is a heavy source of nectar and pollen at the moment in April when bumblebee queens are founding nests and honeybee colonies are building up. A crab apple in flower hums.

Birds. The fruit of the wild crab and of varieties such as Red Sentinel and Evereste hangs on the tree until January or February. Blackbirds, thrushes, fieldfares and redwings strip it in the hungriest weeks of the year, and the tree feeds the caterpillars of several moths in summer. It is one of the best single trees for wildlife in a small garden, alongside the hazel and the elder in our guide to edible hedge plants.

Jelly. Crab apples are so high in pectin that their jelly sets itself, and the flavour is sharper and cleaner than cooking apple. A mature tree gives 10 to 20 kg of fruit, which is a year's jelly from a single October afternoon.

Choosing a Crab Apple

For a hedge, a windbreak, a wildlife corner or a pollinator for a field orchard, the wild crab apple is the right tree: native, tough, self-reliant, and sold cheaply as a bare-root whip. For a garden tree where you also want colour and a longer show, the named varieties earn their price. John Downie has large orange-red fruit and is the classic jelly variety, with a neat conical shape for a small garden. Golden Hornet carries yellow fruit in quantity and is a famous pollinator. Evereste is compact, disease resistant, and holds red-orange fruit deep into winter. Red Sentinel keeps glossy red fruit until spring. Harry Baker has pink flowers and purple-red fruit for a darker jelly.

Size depends on variety and rootstock. The wild tree reaches 6 to 8 m over decades; named varieties on garden rootstocks sit at 4 to 5 m and can be kept smaller. Our crab apple is sold as a young bare-root tree; ask us which type is in stock this season if a particular fruit colour matters to you. Whichever you choose, one tree is enough, because crab apples are self-fertile.

Crab Apple Quick Facts

• Latin name: Malus sylvestris (wild crab); garden varieties are Malus hybrids

• Hardiness: fully hardy, well below minus 20 °C

• Pollination: self-fertile; pollinates most apple varieties

• Position: full sun or light shade; tolerates wind

• Soil: any reasonable soil including clay, as long as it is not waterlogged

• Size: 4 to 8 m depending on variety and rootstock

• Planting: bare-root November to March

• Flowers: late April to May, for three to four weeks

• Fruit: September to October, hanging into winter on many varieties

• Pruning: minimal, in winter

Step 1: Choose the Spot

A crab apple is not fussy. It wants sun for the best blossom and fruit, tolerates part shade and wind, and grows in heavy clay, thin chalk and ordinary garden soil as long as water does not stand in winter. Give it 3 to 4 m of space, or plant it as part of a mixed hedge at 1 m spacing where it will be cut and stay shrubby. For pollinating apples, plant it within 20 m of them; closer is better, and in the same block of trees is ideal.

Step 2: Plant Bare-Root in Winter

Plant between November and March on a day when the soil is neither frozen nor saturated. Dig a hole wide enough to spread the roots flat and only as deep as they are, set the tree at the soil mark on its stem (or with the graft union 5 to 10 cm above the ground on a grafted variety), backfill with the soil you dug out, firm with your heel and water once. Stake a tree over 1 m tall on the windward side for two years. Mulch a 1 m circle and keep it free of grass for three years. No fertiliser in the hole. Our guide to planting a fruit tree has the full method.

Step 3: The First Years

Water in dry spells through the first two summers and leave it alone otherwise. A crab apple usually flowers in its second or third spring and fruits lightly the same year, with a full crop by year five. Fit a guard if rabbits, hares or deer visit; the bark of a young apple is a favourite.

Step 4: Prune Lightly, in Winter

Crab apples need almost no pruning and look worse for too much. In winter, between December and February, remove dead, damaged and crossing branches and anything growing into the centre, and that is all. Shape a young tree in its first three winters by shortening the main shoots by a third to build a strong framework, then stop. Never prune a crab apple in summer if you can avoid it, and never hard; it responds with water shoots that carry no flowers.

Step 5: Harvest

Pick from late September into October, when the fruit comes away with a twist and the first ones are starting to drop. For jelly, pick when fully coloured but still firm, because that is when the pectin is highest. Leave a share on the tree for the birds, and on the long-hanging varieties leave most of it, since that winter fruit is the point.

Crab Apple Jelly

Wash 2 kg of crab apples, cut out any bad bits but leave skins, cores and stalks, and put them in a large pan with water to just cover. Simmer for 25 to 30 minutes until the fruit collapses. Pour the lot into a jelly bag or a muslin-lined sieve over a bowl and leave it to drip overnight; squeezing makes the jelly cloudy. Measure the juice, add 450 g of sugar for every 600 ml, bring to a rolling boil and boil hard for 8 to 12 minutes until a drop on a cold plate wrinkles when pushed. Skim, pot into hot sterilised jars, and seal. It sets rose-pink to amber depending on the variety, and goes with roast pork, lamb, cheese and hot buttered toast in equal measure.

Troubleshooting Crab Apples

Black or brown spots on leaves and fruit. Apple scab, worst in a wet summer. Rake up fallen leaves, prune for air, and choose a resistant variety such as Evereste for a new tree. The fruit is still fine for jelly.

Sunken, cracked bark on a branch. Canker. Cut the branch back to clean wood in winter and burn it.

White fluff in the bark crevices. Woolly aphid. Scrub it off with a stiff brush in spring; established trees shrug it off.

Blossom but no fruit. Frost on the flowers, or the tree is still young. Crab apples are self-fertile, so a partner is not the problem.

FAQ: Crab Apple Trees

Will a crab apple pollinate my apple tree? Almost certainly. Crab apples produce heavy pollen over a three or four week flowering period that overlaps with nearly every apple variety, which is why orchards use them as universal pollinators. Plant it within 20 m of the apple, and closer if you can.

Are crab apples edible? Yes, cooked. Raw crab apples are too sour and astringent to eat, but they make excellent jelly, fruit cheese, chutney and verjuice, and a few can be dropped into any apple pie or jam to help it set. The fruit of ornamental varieties is edible in the same way; none is poisonous.

How big does a crab apple tree get? The wild crab apple reaches 6 to 8 m over many decades. Named garden varieties on standard rootstocks usually sit at 4 to 5 m, and compact types such as Evereste can be kept to 3 or 4 m. All of them can be grown in a hedge and cut annually.

When does a crab apple tree fruit? From its second or third year after planting, with a full crop by year five. The fruit ripens from late September into October. On the wild tree and on varieties such as Red Sentinel and Evereste it then hangs on the bare branches into January or February for the birds.

Does a crab apple need a pollinator itself? No. Crab apples are self-fertile and one tree sets fruit on its own. It is other apples that need the crab apple, not the other way round.

Planting a Crab Apple This Winter

Earthling Plants grows crab apples at our nursery in Co. Wicklow and ships them bare-root through the dormant season to Ireland, the UK and the EU. If you are planting an apple this winter, plant the crab apple beside it and both will crop. If you are planting a hedge, put one every few metres. The rest of the trees we recommend for a cool climate are in our guide to the best fruit trees, and the crab apple's place in a boundary is in the edible hedge guide.

Related reading: The best fruit trees to grow in Ireland · Plant a fruit tree like a pro · The best plants for an edible hedge