The theory

It seems obvious that any newly planted tree will respond well to a lovely deep hole to send its roots down into and a sturdy prop to lean against when it is first planted. The stress of being hoiked out of the nursery and tipped out of its pot is enough to cope with, surely, without having to send out delicate roots to battle through hard ground or stand up to battering winds.  

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It is often recommended that the right way to plant a tree is to dig a hole twice as deep and wide as the root ball and to anchor the tree firmly so that it doesn’t move in the planting hole and so roots won’t be damaged.  It is simply common sense.

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Except that the tree team at RHS Wisley have other ideas, as do the gardeners at Kew, and the fellows down at the Woodland Trust barely mention staking at all. So what is the truth about successful tree planting?

 

The truth

Just as when you give a shrub a hair-cut the shrub will respond by putting on a spurt of new growth from the tips of the cut branches,  so the plant roots respond by sending out a network of new roots if the root tips are rubbed off by the gentle movement of the rootball in the planting hole. Far from being damaging, this proliferation of new root growth is wonderful for the plant.

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The same stress-related growth is evident when it comes to the trunk. If the stake reaches all the way up the trunk to the canopy and is secured so firmly that the trunk never bends, that trunk will never be subject to the motion that encourages it to put on girth,  and the first time it is exposed to really strong winds or a substantial snow load it will break.

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Both roots and trunk, need to be exposed to the mechanical stresses and strains of the great outdoors in order to develop the structure and strength to cope with the conditions they will be exposed to as the tree grows.

 

The Do’s and Don’t’s of Tree Planting

Dig the planting hole only as deep as the root ball itself but twice as wide, then thoroughly rough up the base and sides of the hole so the roots can easily penetrate through the sides and base and out into the surrounding garden.

Release the tree from its pot and tease the roots out of their comfort zone; the last thing you want is a nice, tidy root ball! Any roots that are damaged, misshapen or inflexible should be pruned back to encourage new, healthy ,pliable growth. 

Plant the tree in the centre of the hole and backfill with the excavated soil. There is no need to add any soil conditioners or other materials (save that for your annuals and vegetables), but do ensure that the tree is well firmed in.  Providing a rich but restricted environment will only encourage roots to remain in the comfort of the planting hole...just what you don’t want.

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By all means replace the turf around the tree - but put it upside down. Let the tree become well established before allowing anything to grow around its base.  Grass is thirsty and hungry and your tree doesn’t really need that sort of competition when it has just been planted. Cover the area around the planting hole with 2 to 3 inches of good, rich compost mixed with well rotted manure to act as a slow release fertilizer and to keep the ground beneath nice and moist, but don’t allow the mulch to come into contact with the trunk of the tree.

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Provide a stake that is only 1/3 the height of the trunk. The purpose of the stake is only to keep the tree upright and to stop violent rocking, and no more. Any healthy nursery-grown tree should have a trunk that is strong enough to withstand strong winds, and your aim is to encourage the formation of a good sturdy trunk which will grow stronger year on year. Hammer the stake firmly into the ground, avoiding the rootball, then attach it to the tree with wire or rope threaded through a piece of old hose to protect the bark from friction damage or from the rope becoming embedded in the trunk. Allow the tree a little movement. Only leave the stake in place until the tree has established a good root system - 6 to 12 months - then remove it and let the tree get with growing all on its