Why has my tree not come into leaf this spring?

The scratch test that tells you in ten seconds whether it is alive, the species that are simply late, and the six causes of genuine spring failure.

Difficulty: beginner
Time: 30 min
Read: 5 min

Short answer

Scratch a twig with a thumbnail. Green and moist underneath means alive — be patient, because ash, oak, mulberry and walnut leaf very late. Brown and dry means dead wood, so work down the branch until you find green, and check the trunk base and roots for the cause.

Every spring people write off trees that are merely late. Species differ by six weeks or more in leafing date, and a cold or dry spring shifts everything. But a tree that is genuinely failing to leaf out usually has a root or base problem that happened months earlier, and the spring is simply when it shows.

What you'll need

A thumbnail or a knife
A spade (optional)

Step by step

Do the scratch test.Scrape a sliver of bark from a small twig with a thumbnail or knife. Green and slightly moist underneath means living tissue. Brown, dry and brittle means that twig is dead. Test in several places around the tree, high and low.
Work inwards to find where the life stops.If the twig tips are dead, test progressively further back along the branch, then on the main limbs, then on the trunk. Where the green starts is where the surviving tree begins, and that tells you how much you have lost.
Check whether the species is just late.Ash, oak, mulberry, walnut, catalpa, robinia and figs are all notably late and can be bare well into May. Mulberry in particular is proverbially the last thing in the garden to leaf. Do not condemn a tree before the end of May.
Consider the weather.A cold spring delays everything by weeks, and a late hard frost after growth has started can kill the emerging leaves — which then flush again from secondary buds a few weeks later, usually successfully.
Check the base and root flare.The most common causes of spring failure are underground or at ground level: waterlogging over winter, drought the previous summer, root damage from trenching or building work, mower and strimmer damage girdling the trunk, honey fungus, or a tie or guard left on and now constricting the stem.
Look for a constriction.Tree ties, rabbit guards, spiral protectors and labels left on a growing stem cut into it and eventually girdle it. This kills a surprising number of young trees and is entirely preventable. Check and loosen every tie and guard annually.
Dig gently and look at the roots on a young tree.On a recently planted tree, ease the soil back. Roots circling in the shape of the pot, a dry root ball inside wet surrounding soil, or planting too deep with soil over the root flare are all common and all fatal in the second or third year.
Check for a leaf-eating pest.Where leaves emerged and then vanished, look for caterpillars — winter moth, ermine moth, oak processionary in some areas. Most trees refoliate later in the summer after early defoliation and recover fully.
Wait before removing anything.A tree that has lost its buds to frost or defoliation often flushes again from dormant buds weeks later. Give it until midsummer before deciding, and remove obvious deadwood only.
Prune back to living wood once you know.Cut dead branches back to a point in sound green wood, just outside the branch collar. If a tree is dead to the base, remember it may still need consent to remove if it is protected — dead trees have exemptions but they are narrow, so check.

Tips

Newly planted trees fail in year two more often than year one, because people stop watering after the first summer. Two full summers of watering is the rule.
Half a tree leafing and half not usually means a root or trunk problem on the dead side, or a girdling injury. Look at that side specifically.
A tree that leafs late but then grows normally is not a problem. Note the date it leafed and compare next year.

Common mistakes

Removing a tree in April because it looks dead — Several common species leaf in May. The scratch test costs nothing and settles it.
Leaving ties and guards on for years — They girdle the stem as it thickens and kill the tree from a cause nobody looks for. Check annually and loosen or remove.
Feeding a tree that has failed to leaf — If the roots are damaged or waterlogged, fertiliser adds stress. Find and fix the cause first; feeding is not a resuscitation method.
Watering more when the ground is already waterlogged — Winter waterlogging is one of the commonest causes of spring failure, and more water makes it worse. Check the soil before assuming drought.

If it doesn't work

Twigs green under the bark, no leaves yet in April

Cause: Late-leafing species or a cold spring — Fix: Wait. Reassess at the end of May.

Tips dead, green wood further back

Cause: Dieback from frost, drought or stress — Fix: Prune back to sound wood, mulch, water in dry spells, and investigate the underlying stress.

Whole tree brown under the bark

Cause: Dead — usually roots or a girdling injury — Fix: Establish the cause before replanting, and do not plant the same species in the same spot.

Leaves emerged then disappeared

Cause: Caterpillar defoliation or late frost — Fix: Usually refoliates in summer. Water and mulch to support the second flush.

One side of the tree bare

Cause: Root damage or trunk injury on that side — Fix: Inspect the base and the ground on that side for trenching, compaction or mechanical damage.

Questions people ask

How do I know if my tree is dead?

Scratch the bark on several twigs and on a main limb. Green and moist underneath means alive; uniformly brown and dry throughout, including at the base, means dead. Do this before deciding anything, and repeat in late May if unsure.

Which trees leaf latest?

Ash, oak, mulberry, walnut, catalpa, robinia, fig and Indian bean tree are all late — mulberry proverbially last. Being bare in early May is normal for these.

Can a tree recover from losing all its leaves?

Usually yes, once. Trees hold reserves and refoliate from dormant buds. Repeated defoliation over several years exhausts those reserves and is much more serious.

My newly planted tree has not leafed — what went wrong?

Most often drought in the previous summer, planting too deep, a dry or circling root ball, or a tie left tight. Ease the soil back and look at the roots and the stem base before replacing it.