Your gardening work for the weekend

Often trees and shrubs need to be replaced with new landscaping, for example when building an extension. Rather than throwing these plants away, it is often possible to move them. The older and larger the plant, the more difficult it is to move them.

On the other hand, Capability Brown and his contemporaries were known to have dug up mature oak trees and dragged them with a team of horses to a new location, replanted them, shored them up, and – remarkably – they survived. The modern equivalent, the tree spade – a giant shovel mounted on a vehicle – is only feasible in very large gardens. If you have builders, beware of excavator drivers – they usually overestimate their skill at replanting trees.

Digging up and moving a mature Mahonia gracilipes (Photo: Neil Hepworth/RHS)

Trees and shrubs planted less than five years ago have limited root balls and can be dug up and replanted relatively easily. Roses, magnolias and some leguminous shrubs lack fibrous roots and are difficult to replant unless recently planted and usually need to be replaced.

Conifers are best transplanted now, before winter, or in the spring – although when soil conditions permit and the garden is sheltered from winds, they can be moved in winter. Windy conditions quickly dry out uplifted conifers. It is best to move deciduous plants after they have dropped their leaves and before the leaves burst in the spring, whenever the soil is dry enough. In any case, keep the roots wrapped once lifted and before planting so they don’t dry out.

Preparation makes a big difference – bare-rooted trees or plugged shrubs dug into the nursery ground are “trimmed” at regular intervals during their multi-year growth period, which, by breaking the main roots , induces fibrous root masses that help the plant survive transplanting. In gardens, it is ideal to start the winter by digging a narrow trench around the plant, cutting off all the roots and filling the trench with soil mixed with sand and compost.

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The following year, the plant will have developed new roots and will be in a much better position to move on. It is not necessary to prune more than usual, it is often enough to remove broken or dead shoots before moving. In practice, this is the exception where a year of preparation is possible, but even without preparation satisfactory results are possible.

The soil should now be moist enough to move the plants without watering first, but water well the day before if in doubt. It is best to tie the branches before digging the plant to facilitate access and limit breakage. The ideal is to move as large a root mass as possible, but realistically the weight of the tree, roots and soil limits what can be done even if – as advised – several people help with this .

Transplanting a large box tree (Photo: Tim Sandall/RHS)

Explore the ground with a spade and pitchfork to assess where the roots are, then dig down to get a good-sized root ball that can be handled by available hands. This involves digging trenches around the plant and then digging. Before you start digging, and once you know the approximate size of any root ball, dig the new planting hole, about 50cm wider than the planned root ball to minimize the time between lifting and replanting. The new planting hole should be forked slightly to loosen the sides, but not the base.

Use an old saw to cut through any thick roots that are resistant to the spade. Use poles or lengths of wood to act as ramps and levers to extract the root ball from the hole, ideally by slipping a burlap or tarp under the plant which can be lifted by the corners (tie a knot here if necessary ). Once lifted, wrap the root ball and carefully slide/carry the plant to its new position.

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Adjust the depth of the planting hole so that the plant is planted at the same depth as it was when it was lifted. Firm the soil as you fill in around the newly positioned plant, spreading the roots evenly without packing the soil down, but making sure there is good soil in contact with the root ball all around. Once replanted, stake as needed as the plant will now lack stability and wobbly plants will not root well.

Uprooted plants can be held or moved by vehicle if necessary as long as they are well wrapped. They can also be containerized if necessary using a coarse free-draft bark-based potting mix.

Watering will be necessary during post-planting drought and all summer for the first two years. Mulching, spring feeding, and careful weed control will also help the plant survive.

Terri S. Tomasini