Moving trees, also known as transplanting, involves digging up a tree’s root system and surrounding soil – known as a rootball – and then replanting. Key is to keep the rootball intact through careful wrapping, and moist, which stops the roots from drying out.
Transplanting Fundamentals
A tree’s root system is made up of thick, woody roots that anchor a tree into the soil and very-fine, root hairs, which absorb most of the water and nutrients. When you dig up a tree or a shrub, you’ll lose most of these root hairs regardless of how careful you are.
Root hairs will start to regenerate upon planting, but adequate coverage can take weeks, and full regeneration years. Thus a tree is temporarily deprived of water and nutrients – a event known as transplant shock.
Transplant shock can be minimised with good capture of a tree’s root system and through ensuring these roots remain hydrated. Inadequate capture or insufficient moisture can kill a tree.
Young trees regenerate faster and possess smaller root systems, so capture is easier. Older trees are significantly less likely to survive transplantation and huge trees will require specialist help. (More on this later.)
Deciduous trees are best transplanted in autumn, when a tree is dormant, and has shed its leaves. This will give time for a tree to establish its root system, before it starts to grow come spring.
As evergreen trees don’t shed their leaves and continuously lose water through their leaves, they will need time to produce new roots before the ground freezes. Thus moving trees in autumn and spring is recommended when the ground is relatively warm. You could hypothetically move a tree in a mild winter, but only if the ground remains unfrozen.
The day you decide to move your tree is important as wind and heat will dry out your rootball. Choosing an overcast, humid day is wise.
Root Pruning
Root pruning is recommended in the case of old, established trees, whereby a portion of the root system is lost in transplantation. With established trees, the roots near the trunk are primarily old, woody roots with limited absorption capabilities. Pruning such roots will lead to the growth of new feeder roots, which will grow root hairs upon transplantation.
There are two methods of root pruning: spading and trenching. The former involves making a circular cut all the way round the plant, cutting through existing roots with a spade. Trenching involves digging a trench 8-12 inches wide and 12 inches deep, and filling it with soil rich in organic matter – two parts topsoil and one part compost. It is in this trench that the plant will grow new feeder roots.
Root pruning is done well in advance of the transplantation date – sometimes up to a year. To determine its success, dig into the soil and and look for new roots.
Determining Rootball Size
The rootball is the mass formed by the roots of a plant and the soil surrounding them. In most cases, it is impossible to take the whole root system, so you simply take a portion large enough to support the tree. This is known as the rootball.
The size of a rootball is based on a tree trunk’s diameter, measured 6 inches from the ground with small trees, and 12 inches above the ground with trunks above 4 inches. Trunks can be measured with a caliper, or approximated with a ruler.
The ratio of rootball diameter to trunk diameter falls as a tree becomes larger. This is because trees require a minimal width.
For thicker trees, ratios of 10:1 and 8:1 are standard, although can be higher for mature specimens.
You need to work out the rootball’s depth and this is based off rootball diameter. As trees grow wider than they grow deep, the rootball depth doesn’t have to be as big as diameter.
While some species have the ability to suffice in compact, poorly aerated soils, there are no intrinsically deep rooted species, and every plant will adapt to its conditions. Trees will produce larger root systems in good quality soils, free of competition or man-made barriers.
Site Evaluation
Ideally, the site should match the tree’s recommended growing conditions, including light, soil pH, drainage and exposure.
As trees orient towards the sun it is worthwhile marking north on the tree’s trunk and then planting as so it faces the same way. This will allow the tree to gather resources more effectively.
Moving Day
Watering the rootball in the days leading up to the dig will preserve moisture and help keep the rootball intact. Once you have dug your rootball, carefully wrap it in natural untreated burlap, and then sew or tie to prevent cracking.
Move your rootball carefully. A cart or wheelbarrow can ease the load.
The planting hole should be dug before you dig the tree. Minimising the time the tree is out the ground is always useful, but is especially important for evergreen trees.
Give the rootball another soaking before you plant.
It is important to plant at the same depth in the new hole, if not an inch above if you believe the soil below will compress. Digging a wider hole is recommended as it will make it easier to remove the wrapping.
Any non-biodegradable wrapping, ties etc should be removed once the rootball is in the ground. Remove burlap from the sides as far down as possible.
You can then fill the sides with soil rich in organic matter. Don’t compress the soil! Compaction will retard root growth. Just check up on it to see if it needs topping up.
Make sure to mulch upon planting. This will help preserve moisture. Natural mulch shouldn’t touch the base of the trunk.
Remove any turf within the vicinity of the tree’s root system as it will compete for nutrients and water.
Has My Relocation Been a Success?
Once you have planted, all you can do is ensure the rootball remains moist. Check up on a semi-regular basis.
Evergreen trees’ leaves will often yellow and drop to reduce water consumption while it puts out new roots.
Moving Huge Trees
With some trees, you will need specialist help to move. Relocation experts use a special machine called a tree spade that pulls rootballs whole from the ground. Make sure to ask for references and information about credentials and insurance when deciding upon a specific company.
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Jorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!
His ideal afternoon would involve a long walk, before settling down for scones.
Jorge is a journeyman gardener with experience in growing crops.