Malus

Tree of the Week - Entry 5 - September 2026

There's a week in early September when a crab apple stops being about the blossom everyone photographed in May and starts being about the fruit. This is that week. The crabs around Cobham are doing the thing that makes people pause on the pavement: fruit fattening and blushing, weeks before the leaves give any hint that autumn is coming. It's the moment the tree looks most like itself - not the froth of May, but the quieter reveal of what all that flower was actually for.

It's also the best week of the year to choose one. Walk past a mature specimen now and you can see exactly what you're buying: fruit size, fruit colour, how heavily it's cropping, whether the birds have started on it yet. Order a bare-root crab in January and you're buying a description. Buy one now, in leaf and in fruit, and you're buying a tree you've actually met.

And with eating-apple harvest getting under way across Surrey orchards this month, it's worth remembering that half the crab apples in gardens round here aren't really there for jelly at all. They're on pollination duty for a Bramley or a Cox two gardens over - doing quiet, useful work that the eating apple's owner may never think to credit.

Beneath the soil

Here's something worth finding out for yourself, next time you're standing beside an old crab apple. What looks like a thorn on the older wood usually isn't one. On most garden crabs those short, stubby, sideways-jutting growths are spurs - compressed shoots that carry the blossom and then the fruit, year after year, rather than defending the tree against anything. Run a thumb along one carefully and you'll feel it's blunt, not sharp, and if you look in spring you'll find the flower bud sitting right on the end of it.

It's a small piece of tree architecture with a large practical consequence. Because the fruit is borne on these permanent spurs and on the previous year's wood, a crab apple pruned hard after flowering will still flower generously the following year - which is not true of trees that fruit only on new growth. It's also, quietly, the reason crab apples make such reliable orchard companions: a tree built to flower on old wood turns up for pollination duty every single spring, rain or shine, rather than sulking after a hard prune the winter before.

Nearly every crab apple sold as a garden tree is a named cultivar grafted onto a rootstock, not a tree grown on its own roots, and the rootstock is doing more work than most people realise. The all-purpose choice for most ornamental crabs is MM106 - semi-vigorous, tolerant of a wide range of soils, producing a free-standing tree of around 3-4 metres that needs staking for its first few years and then stands on its own. More vigorous rootstocks such as M25 suit a bigger, more permanent tree; dwarfing rootstocks such as M9 turn up on trained forms and cordons rather than ornamental specimens. The plant you buy is always two trees joined into one, chosen separately for what happens above ground and below it.

Below the graft union, the more interesting partnership is with soil fungi. Apple and crab apple roots form associations with arbuscular mycorrhizal fungi, and a 2018 University of Sheffield study found that inoculating young apple trees with these fungi improved phosphorus uptake and measurably increased resistance to Neonectria ditissima, the canker pathogen. The same study found that heavy standard fertiliser regimes actually suppressed fungal colonisation and root development - a useful thing to know before reaching for a feed. The practical translation: use a mycorrhizal root dip or granules at planting time, go easy on fertiliser in the first couple of seasons, and let the tree's own root-fungus partnership do some of the establishment work. Water through the first two summers, keep a mulch ring clear of the trunk, and expect staking to come off within three to five years depending on rootstock.

One genetic fact worth knowing, even if it isn't visible: Britain's own native crab, Malus sylvestris, is one of the wild ancestors woven into the parentage of the cultivated apple, alongside the Central Asian Malus sieversii that gets most of the credit. Every eating apple on a Surrey kitchen table carries a little bit of hedgerow crab somewhere back in its family tree.

Practical use

The larger-fruited cultivars - 'John Downie' above all - are the classic choice for jelly and preserves. The fruit is too tart to eat raw but cooks down into a set that needs almost no added pectin. For orchard pollination, plant one within range of eating apples with an overlapping flowering group and fruit set improves markedly; the long flowering season and heavy pollen load of a crab apple make it one of the best insurance policies a small orchard can have.

Wildlife value runs through the whole year: blossom for early bees in spring, fruit that persists into winter for blackbirds and thrushes, and - once softened by frost - a genuinely useful late food source when little else is left. Varieties with persistent, glossy fruit such as 'Red Sentinel' are also cut for winter arrangements and wreaths. The wild form, Malus sylvestris, makes a flowering, fruiting component in a mixed native hedge. And for smaller plots, narrow columnar and genuinely dwarf forms exist for every size of garden, right down to a large container.

Most garden crabs are self-fertile but crop noticeably better with a partner nearby. The fruit is not poisonous - the pips carry the same compounds as ordinary apple pips and should be removed before eating, but the cooked flesh is perfectly good. As for the birds: they will strip the fruit eventually, especially after the first frosts soften it. That's a feature, not a fault, if part of the reason for planting is wildlife.

Care and mistakes

Grow in moderately fertile, moist but well-drained soil in full sun for the best flowering and fruiting. Most will tolerate light shade without complaint.

Things to do:

• Choose a cultivar with good disease resistance from the outset - it does more good than any amount of subsequent spraying.
• Do the formative work properly in the first three to five winters: an open, balanced crown with well-spaced main branches.
• Prune lightly after flowering once the tree is established, removing crossing or crowded growth and leaving the fruiting spurs alone.
• Spread renovation of a neglected, congested tree over two or three years rather than attempting it all in one go.
• Use a mycorrhizal root treatment at planting and water through the first two summers.

Things not to do:

• Don't assume you can keep a full-sized cultivar small with secateurs alone. If space is tight, choose a columnar or genuinely dwarf form from the start.
• Don't treat annual pruning as an autopilot chore - a crab apple that has been properly formed in its early years wants very little thereafter.
• Don't reach for a heavy fertiliser feed in the first couple of seasons; it suppresses the mycorrhizal colonisation that helps the tree establish and resist canker.
• Don't overlook disease on a crab apple as its own problem only - apple scab, canker, and fireblight can all move onto nearby eating apples.

Context and companions

A crab apple sits naturally in an orchard setting, but it earns its place in a Surrey garden of almost any size. The columnar 'Bolero' from the Ballerina Series stays narrow enough for a tight plot or a large container. 'John Downie', with its white flowers and large conical red-and-yellow fruit, is the classic jelly-maker's tree and an excellent pollinator. 'Red Sentinel' carries its glossy red fruit well into December and beyond. For something less expected, Malus coronaria 'Elk River' - a hardy American sweet crab with large, highly scented single pink flowers - is the kind of tree that starts a conversation.

The Woodland Trust, writing on Malus sylvestris, notes that "this 'crabbed' appearance may have influenced its common name, 'crab apple'" - a reminder that even the name of the tree carries a small piece of observation in it, the gnarled and twisted habit of an old wild specimen left to its own devices in a hedgerow.

In a mixed planting, crab apples sit comfortably alongside other Rosaceae - rowans, hawthorns, wild cherries - and make an honest companion to any eating apple that needs a reliable pollinator within reach. They are not demanding neighbours. They ask for decent drainage, reasonable light, and the occasional clear-out of congested growth. In return they give blossom, fruit, wildlife, and - in the best varieties - a winter silhouette hung with colour long after everything else has gone bare.

Questions people actually ask

The question that comes up most reliably is whether a crab apple will pollinate an eating apple. Usually yes, provided the flowering periods overlap. Crab apples flower for longer than most eaters and are used commercially for exactly this reason - they're a dependable presence during a window when a Cox or a Bramley needs company.

People also ask about size, and this is where it's worth being honest. Many popular cultivars reach 6-10 metres with a similar spread if left to their own devices. That's fine for a paddock; it's a squeeze in a Cobham back garden. The answer isn't to buy the tree and fight it with a saw every year. The answer is to choose a columnar form such as 'Bolero', or a genuinely dwarf cultivar, from the beginning.

On pruning: formative work in the dormant season for the first few years, then light pruning after flowering once the tree is established. The timing matters because pruning before flowering removes the spurs that were about to carry blossom - and a crab apple's whole appeal, in May as much as September, depends on those spurs being left to do their job.

Come and see our crab apple selection for yourself. Cedar Nursery is in Cobham, Surrey - visit us to find a tree you've actually met, in fruit and in leaf, before you commit to planting it.

Come and stand under it. Cedar Nursery, Cobham, Surrey.