March fruit trees: correct planting depth at the graft union

When you plant an apple, cherry or apricot tree in the garden in March, you usually think about feed, choosing the right cultivar and watering. Hardly anyone pays attention to a tiny area on the trunk that decides whether the tree survives, flowers well and later carries a worthwhile crop. Yet this is precisely the spot that is far too often buried under soil - with consequences you typically only notice once the tree is already struggling.

The most common planting mistake: set too deep and slowly suffocated

Why “well-intended” planting can quickly turn fatal

Many gardeners like to push a young tree extra deep into the ground. The reasoning sounds sensible: a deeper position means more stability and better protection from wind and weather. So soil is heaped up, firmly trodden down, and sometimes a small mound is even built right against the trunk.

In practice, that method acts like a suffocating cushion. The base of the trunk needs oxygen and air movement. If soil completely surrounds it, moisture is trapped, the bark stays wet for long periods, and the tree cannot “breathe” at this sensitive point.

"If you bury the base of the trunk, you take away the fruit tree’s air - and often its chance of flowering and cropping."

Damp soil against the trunk: a fungus haven instead of dream fruit

Trunk bark is made for open air, not for life under wet soil. If it remains constantly damp, what’s known as maceration begins: the tissue softens, becomes vulnerable, and gives fungi and rot an easy way in.

Below the surface, the trunk gradually decays. From the outside the tree may still look more or less normal at first, but internally the supply system starts to fail. The transport channels clog, and sap reaches buds and young shoots only poorly. The result is weak growth, few flowers, and little or no fruit.

The crucial zone: how to recognise the graft union

Key reference points: the root collar and the graft swelling

Almost all nursery fruit trees are grafted. In other words, a desired cultivar - for example a particular apple - is joined to a tougher rootstock. This “join” on the trunk is the critical point that must never end up below soil level.

Two areas are important:

• Root collar: the transition between roots and trunk, right at ground level.
• Graft union: usually a few centimetres above, visible as a thickening, small bump, scar, or slight kink in the wood.

If you look closely at the tree, you can almost always find this area without difficulty. It looks like a healed scar - and that scar plays a major role in vigour, willingness to flower and resistance to disease.

Why this “scar” drives flowers and fruit

At the graft union, the chosen cultivar meets the rootstock, which is often selected for strong root growth, frost hardiness or more restrained size. That combination is what makes modern fruit trees suitable for gardens at all.

If this zone is covered with soil, something deceptive happens: the cultivar tries to form its own roots so it can separate from the rootstock. That takes a great deal of energy. The tree pours its strength into emergency measures instead of forming flower buds.

"If the graft union ends up under soil, the tree forgets flowering and fights to survive."

The advantages of the carefully selected rootstock are then lost: less resilience, a later start to cropping, and weaker blossom. In the worst case, the tree can fail completely.

How to plant properly in March: the golden height rule

The ideal position: keep the graft union clearly above soil level

When planting, there is a straightforward rule of thumb: the graft union must sit 5 to 10 centimetres above the finished soil level. The root collar should be just above the soil surface - never beneath it.

Proceed like this:

• Dig the planting hole deep enough that the roots can sit comfortably without bending.
• Shape a small, firm mound of soil at the bottom of the hole and spread the roots over it.
• Hold the tree so the graft union is clearly above the surrounding ground level.
• Backfill and gently firm the soil, without burying the base of the trunk.

This raised position keeps the sensitive area dry and well ventilated. Sun and air can reach the scar, and fungi and rot have a much harder time.

A trick to stop the tree sinking later

Freshly loosened soil contains a lot of air and settles over the following weeks and months. As it does, the tree can slip down unnoticed - and eventually the graft union ends up sitting in damp soil after all.

A simple trick prevents this: when planting, lay a cane or stick across the planting hole. Position the trunk so the graft union sits level with the underside of the stick or slightly above it. Only then do you backfill. This visible reference point helps stop the tree from settling too deep.

If the tree is already suffering: warning signs of being “buried alive”

Clear symptoms in spring

A fruit tree planted too deep tends to show distress gradually. Many gardeners read the signs as a “poor variety” or a “bad year”, when in fact the tree is asking for help.

Warning signs include:

• Shoots stay short and thin, with very little annual growth.
• Leaves yellow early or remain small and pale.
• Buds swell but do not open, or they dry out.
• In spring the tree looks generally “frozen”, while others have already started into growth.

If this combination appears, it’s worth checking the base of the trunk. If there is a mound of soil that reaches well above the root collar, this mistake is often the cause.

Rescue action: expose the trunk base again

Once you spot the problem, there is only one real remedy: free the base of the trunk. Use your hands or a small trowel to carefully pull soil away from around the trunk.

"The aim of the rescue is a shallow basin around the trunk, with the graft union and root collar back in open air."

Care is essential. Surface roots must not be cut, and the bark must not be damaged. If you proceed gently, you give the tree a second chance. Over the following years the root system can recover, and the willingness to flower usually returns.

Checklist for long-term healthy fruit trees

What to check as you backfill the planting hole

When you fill in the soil for the final time, it pays to take a quick look at these points:

• Graft union visible and at least a hand’s breadth above the soil.
• No mound of soil right against the trunk that traps moisture.
• Create a watering rim so water runs to the roots slightly further out, not directly onto the trunk.
• Firm the soil with light pressure only - don’t compact it like concrete.

Working this way supports the tree’s natural structure instead of fighting it. The root area remains active, the trunk bark stays dry, and flower buds receive a steady supply of nutrients.

Why correct planting depth achieves more than feed and special compost

Many gardeners spend money on expensive composts and fertilisers while the real make-or-break factor is just a few centimetres of height at the trunk. A fruit tree set at the right depth often needs less feeding, copes better with dry spells, and produces its first crops sooner.

In a sense, the graft union is the fruit tree’s “control centre”. It influences vigour, the start of flowering and cropping behaviour. Cover it up and you interfere with that system; leave it exposed and you fully benefit from the work nurseries and breeders have already put in.

Especially in small gardens where every square metre matters, the difference between a wrongly planted tree and a correctly planted one can decide whether you are carrying baskets of apples after five years - or still standing puzzled in front of a sparsely flowering crown.

Checking the trunk takes only a few seconds, but it can prevent years of frustration. Anyone planting this spring - or looking critically at older trees and exposing the base if needed - quietly but very effectively lays the foundation for an orchard that crops well for many seasons.