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Autumn is a great time to take stock of your garden and make improvements, or at least start planning for next year.

Even after planting a garden from scratch, some attention is required after a few years and more mature gardens may need more drastic action if they have not been maintained regularly.

In mainly perennials borders, if the border needs a big overhaul it might be best to lift all the perennials and any small shrubs, divide the perennials as necessary and start again. (They can be left in bags of moist compost in the shade for several days.) This also allows you to clear any weeds and fork in organic matter which will improve the soil, and thus plant health, before replanting. Take care that you do not damage any roots of existing shrubs and trees in the process.

Re-shaping borders

Consider whether the borders are the right shape and size. In very thin borders only one row of plants may be possible. A wider border will allow you to layer plants of different sizes, shapes, forms, textures and colours.

Equally, if you have very wide borders that you find difficult to get into, reducing the width can make the garden more manageable.

Plant renovation or removal

I believe that you shouldn’t keep a plant if you don’t like it, and of course, anything dead or diseased should be removed. However, do consider the following if you are thinking of removing trees and mature shrubs:

• They provide a habitat for wildlife, not only birds and bees, but insects, lichen and fungi - all essential parts of the ecosystem.

• They provide a wide range of other environmental benefits: carbon capture to reduce climate change, cooling of the air, preventing flooding and erosion, creating shade, and capturing dust and pollution.

 If you would like to keep the plant but its shape is a problem e.g. it is overgrown, first consider whether it can be pruned.

Many shrubs can be hard pruned almost to the ground and will regenerate e.g. Hypericum, Choisya and Laurels. Some are best done over two or three years e.g. Yew.

Some evergreens can be crown lifted, that is, the lower branches removed. This opens up the area at ground level allowing more light to planting below it and also creates structural interest.

Deciduous shrubs can be either pruned to the ground or several large branches removed each year to encourage regeneration.

Some Mediterranean plants like Lavender and Cistus do not respond to hard pruning and are best replaced.

 When doing any structural pruning it is a good idea to stand back from time to time to look at the effect, and assess which branches to remove.

 In terms of overgrown climbers, clematis, roses and honeysuckle will usually tolerate being pruned down to about 60cm.

With all plants that have been heavily pruned, feed, mulch and ensure they are watered in dry weather to stimulate new growth.

If you are not sure when and how to prune, a good reference book is the RHS Guide to Pruning. Alternatively, ask a professional for advice.

Dividing perennials

Perennials that have a dead area in the centre of the clump, or have spread outside their allotted space, or have weak flowering due to congestion can be divided. (For spreading types with fibrous roots you may not need to lift them, just insert a spade and remove the excess sections.) These can be replanted in sections to make new clumps. Avoid making them any smaller than about 10cm diameter and ensure each clump has plenty of root attached.

 

Weeding

Annual weeds can be removed using a sharp hoe on a dry day when they can be left on the surface to die or they can be picked out manually.

Perennial weeds should be dug out by hand removing all of the root if possible. For persistent weeds, if pulled regularly, they will slowly weaken and die. These could also be treated with a glyphosate-based herbicide applied onto the leaves. Follow the instructions carefully. The plants will suddenly die down after about 2-3 weeks at which time you can clear away the dead foliage and start to replant. You may need to repeat the application on difficult areas with persistent weeds. Do not allow the herbicide to touch any plant you want to keep as it may kill that too. If you do feel you need to use it, do so sparingly as there is evidence that it negatively affects wildlife and is carcinogenic to humans

New plants and planting

When thinking about what new plants to add to your border, look at what you already have and think about how you could add interest at each season, also thinking about colour, texture and form.

Ensure that you leave sufficient space to allow the plants to grow and spread.

Space between shrubs can always be filled with summer annuals to add interest and provide good groundcover in the first year or two whilst the shrubs fill out. Trailing annuals such as trailing Lobelia and Calibrachoa work well as they cover the ground but do not get tall so do not overwhelm the new shrubs.

Ongoing maintenance

It is better to regularly prune, weed and edit than waiting several years until the task is overwhelming.

Most shrubs will benefit from a light prune annually to keep them in shape and prevent them becoming overgrown and unmanageable.

Likewise, keep an eye on perennials, and lift and divide as necessary, and keep lawn edges neatly trimmed so that the edge is not lost.

An annual mulch of organic matter after the new border is planted and annually in spring will help to prevent weed growth, reduce moisture loss and improve the soil, so keeping the plants healthier.

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