Cutting Back: Pruning for Renewal

In the Southern Hemisphere, winter has well and truly arrived. The coolest season marks the final retreat of many seasonal plants, and sun-loving flowers have well finished their last florific hurrah. In cooler climates, brightly coloured autumnal leaves have now have dropped, exposing the structure and stems of deciduous plants and trees.

Herbaceous perennials like rudbeckia, echinacea, agastache and echinops have drawn nutrients back into their root systems and their leaves, flowers and stems have died back. The garden slows down as the temperature cools, and it feels like the culmination of everything you have been learning in your garden comes to a rewarding reckoning. Each season brings a continuous supply of delights and wonders, but the cooling pause has a feeling of generosity. It is a point in time to reflect on garden lessons from previous seasons, to scheme and dream for the seasons to come. 

Pleasures from gardening practicalities

While worldly affairs and the news cycle are not in our control, there is immense satisfaction to be gleaned from the practicalities of gardening. Planting plants, potting seedlings, and mulching have immediate and tangible results. Pruning is a garden job I always find extremely satisfying.

Pruning also evokes wonder, in the ways plants respond to it. Many pruning techniques are undertaken to encourage growth and trigger renewal. Pruning techniques like tip-pruning or ‘pinching out’ encourage plants to grow with a greater density, and deadheading spent flowers encourages further flowering.

Pruning is not necessarily about controlling growth, restricting plants to our ideals and aesthetics. Pruning can also be an initiator, a call for a plant to grow more.

In garden spaces heaving with annuals, grasses and other perennials, the start of winter is a time to pick up the secateurs for a ‘cut back’. This usually refers to a large-scale prune where spent annual flowers are pulled or cut out, and perennials get a big haircut to encourage renewal when the season warms after winter.

Cutting back Herbaceous Perennials vs Evergreen Perennials

Perennials are plants with no woody growth, unlike shrubs and trees, and can grow for several years. They include plants like salvias, wahlenbergia, agastache, billy buttons, pelargoniums and grasses. There is a distinct difference in how herbaceous and evergreen perennials operate through the season. Evergreen perennials will keep their leaves year-round, while herbaceous perennials are often deciduous. This group of perennials will draw all their nutrients back into their roots and appear to ‘die back’ to the ground level when the plant is dormant, reshooting when the seasons begin to warm.
 
After herbaceous perennials have finished their summer wonder and have retreated into dormancy, the plants can be cut back close to the ground, making way for new growth. Evergreen perennials are still actively growing and won’t enter a dormancy. After the flush of spring and summer growth, there is a wonderful opportunity to give them a substantial haircut, removing anywhere between a half and a third of the foliage, depending on how fast the plant is growing, encouraging the plant to rejuvenate with new growth.
 
When pruning evergreen perennials to encourage renewal and growth, always make a slightly angled cut just above the leaf joint or node at a height you want the new growth to start from. Nodes hold shoots that will emerge and be off on their way in response to the pruning. Shape evergreen perennials into a neat mould shape for even, dense growth in spring.
 
With your technique right, it is now all a simple case of getting into it. Depending on the size of your garden, there may be a fair bit of pruning. Sometimes these tasks are a pleasure to share with garden friends for a weekend session. Keep your secateurs sharp!
 
Tarpaulins of all sizes are useful to collect and move the prunings. A cut-back may generate a big pile of prunings. These can be composted, or even mulched, and returned to the garden. Keep an eye out for weeds – you don’t want any of them in your compost or mulch pile, as there’s a chance they’ll continue to propagate through your garden.    

In extreme climates, the decaying skeletons of plants now dormant in the soil offer a layer of protection from frosts. It may be best to wait until you see signs of emerging shoots before cutting back to make way for them in the coming spring.  
 
In warmer locations, winter can be a great time to cut back before planting, in order to see the garden from different perspectives.
 
A note on sculptural seedheads – some plants are just as beautiful as when in flower (if not more so) during their graceful decline in the garden. A cutback does not need to be one big chop, in one go. You can make creative decisions regarding the plants you cut back first, and the ones you keep for a bit longer to enjoy their decaying beauty.  
 

When to cut back

If cutting back has exposed the soil of your garden, consider planning to lay a layer of thick mulch soon after, to reduce the opportunity for weeds or unwanted self-seeding plants or ‘volunteers’ to emerge in thought the garden.  

Pruning evergreen and deciduous shrubs and trees

 
Pruning is a rejuvenating and guiding force in the garden for all types of plants. While we can encourage more density in the foliage and flowers by pruning evergreen perennials, this is also true for shrubs and trees (both evergreen and deciduous). Pruning encourages the plant to respond with growth. The same technique always applies: cut with a sharp, clean tool just above the node or leaf joint of the plant to encourage sprouting. Always cut on an angle, so moisture drains from the wound.
 
It can often be easiest to prune deciduous trees and shrubs during cooler months when the skeletons of the stems and structure of the plant are revealed. However, I tend to do it at the end of winter, right before the plant takes off in spring. Light pruning or tip pruning of young trees and shrubs will encourage more stems, and greater density of growth, as the plants mature.
 
There are so many creative opportunities for sculpting shrubs and trees. It is not necessarily just hedging and forming balls or flat planes of growth. Pruning can showcase a plant. For example, stunning bark and luminous multi-stemmed trunks can be revealed by ‘lifting the canopy’ – pruning off lower branches at the trunk of a tree or large shrub.
 
When working with thicker stems, a sharp Japanese saw or loppers will be far more effective for clean cuts. Remember, if pruning off an entire branch or entire stem, always get as close to the trunk or base as possible for a clean cut. 

Plants always find a way

Pruning and cutting back is a technique that can be used creatively to rejuvenate and guide your garden, season after season. But it is not essential. It is up to you, as the gardener, to decide how much or how little you prune. Shrubs and trees will grow into their natural forms. Evergreen perennials will continue to grow, but perhaps with slower and more elongated growth. The dead stems and foliage of the dormant herbaceous perennials will decompose over time, and their new shoots will push through.
 
Cutting back lets light in, both physically and metaphorically. Gardeners are able to see clearer, to observe, pause, and take the garden in. To see what is happening – what plants have been lost and which ones are thriving. I find it important to see the garden with a bit more clarity after a big prune, to observe it with hope and anticipation for the seasons to come.