Are your borders looking overgrown and overcrowded? If some of your stalwart shrubs and perennials have outgrown their space or simply aren’t thriving in their current position, it may be time to move them.

Ham & High: A man pushing a wheelbarrow filled with plants. PA Photo/thinkstockphotosA man pushing a wheelbarrow filled with plants. PA Photo/thinkstockphotos (Image: Archant)

The best time to transplant shrubs is while they are dormant, between late autumn and early spring. Choose a day when the ground isn’t frozen or waterlogged.

There’s always a risk when you move plants and the larger the plant, the more risk there is that you’ll lose it. But there are ways to minimise that risk.

Small herbaceous perennials and compact shrubs are relatively easy to move if you water them thoroughly and then dig them up with as much root as possible, repositioning them somewhere where there’s more room or where conditions are more favourable. Water them in well and keep them well watered during the autumn in the absence of rainfall.

Mature shrubs are harder work to move, but it’s best to do it after a bout of rain. Get a friend to help you if the shrub is extremely large.

Generally those that move most easily are the ones with fibrous roots - masses of thin roots which remain shallow in the soil. More problematic to move are those with tap roots, which are much thicker and there are fewer of them. It’s difficult to move these without breaking the roots.

First, decide where you are going to replant any large shrubs. Dig a hole slightly bigger than the root ball of soil is going to be and add organic matter to the soil as well as slow-release fertiliser.

For trauma-free transplanting of large shrubs, first make a wide circle at least 30cm from the shrub with a spade and dig a deep trench following the circle’s curve. Use a garden fork to loosen the earth around the ball of the roots, then gently fork the surplus earth from around the roots.

If the stems or branches of the shrub are unwieldy, tie them loosely with garden string so they don’t snap off or get damaged during the excavation.

Once the ball of roots has been loosened, dig your spade under the root ball as far as you can, levering gently as you go around the circle. The aim is to keep as large a root ball attached to the plant as possible.

When you feel the shrub move, tilt it to one side and slide a length of plastic sheeting or sacking underneath the root ball. Tilt the shrub the other way and manoeuvre the sacking so that it comes underneath the whole root ball, then wrap it up and tie it around the trunk securely, to minimise water loss and keep the root ball and soil intact.

Unwrap the sacking and carefully place the shrub in its original depth. There should be a distinct soil mark on the shrub, so it’s easy to gauge. Fill the hole with displaced soil, firm in gently with the ball of your foot to get rid of any air pockets and give it a good soaking.Water regularly until the plant becomes established and mulch with organic matter. Large shrubs may need support for a year or two.

Some plants react better to being moved than others. Those which are easier to move include rhododendron and azalea, hydrangea, hebe, fuchsia, Choisya ternata and forsythia.

Peonies don’t really like being relocated and it may take a couple of years before they flower again. Shrubs which don’t like being transplanted include ceanothus, berberis, holly, eucalyptus, buddleia, cotoneaster, weigela and lilac. But even if they suffer leaf fall after moving, don’t give up on them because they may come round.