Why planting in the autumn months is often more beneficial to plants...

Ever wondered when’s the best time of year to plant indigenous trees, shrubs and herbaceous perennials in South Africa? Many gardeners will say spring...

However, as a gardener, designer and horticulturalist with many years of practical experience, I have found that the cooler autumn months are generally far superior to springtime when planting out many types of indigenous plant. This also applies to relocating most existing indigenous trees and shrubs in the garden. If left to plant out in spring, these plants often don’t become established until the end of summer. This is especially so now with climate change a reality - summers are generally just getting hotter.

By autumn, the extreme heat of summer is normally over, as the days begin to shorten and the nights become longer and cooler. Newly planted or relocated plants will usually thrive if they are planted in the autumn months, as they will have plenty of time to establish their root systems before the onset of summer again. Autumn rain will also benefit these new or relocated plantings.

 

Dietes bicolor - Yellow wild iris

Obviously, there are some basics which should be followed, when planting and relocating during autumn: 

New plants 

•  If there is little chance of frost in winter, such as in the coastal areas, most new plants can be put in the ground during autumn. 

•  In areas which experience some frost, frost-sensitive autumn plantings should be protected if frost is looming. 
•  Frost-sensitive plants should not be planted out in autumn if they don’t normally grow in very cold, frosty climates.

Relocating existing plants 

•  If the plant is very large and well-established, some trenching around the plant (in its original position) during the previous spring and summer months will need to be done to minimise the root ball. This helps prevent the plant from experiencing any unnecessary stress when being transplanted.
• If the plant normally flowers in autumn or winter, rather wait until spring to move it.
• The notes about frost-hardiness given above also apply to relocating existing plants. 
• Prune back about 15% to 20% of existing leaf/branch material on shrubs and herbaceous perennials only, so that the plant’s energy goes into new root formation. Trees should not be pruned back unless absolutely necessary.

Plumbago auriculata - Cape leadwort

If all goes to plan, autumn plantings will be well established and growing new shoots and leaves when the sap starts to rise at the end of winter.

You may have noticed that many nurseries really only ‘stock up’ with trees and shrubs in the spring and summer months, which sometimes makes it difficult to find plants for autumn planting. If they don’t mind staying in bags for about six months, keep your spring-bought trees and shrubs until the autumn months, then plant them out and see the difference.

Scadoxus puniceus - Paintbrush lily