Peter Dowdall: The switch which drives us gardeners outside has gone off once more
Butterfly bush. If you’ve grown this before, you’ll know it can become a bit of a wild beast if left to its own devices. Picture: iStock
At this time of year, you can almost feel the garden waking up. There’s a sense of movement in the air, with the days stretching out, the birds getting busier, and green shoots pushing their way through the soil.
The switch has gone off in all of us which drives us outside once more. And with that comes so much enthusiasm to get active in the garden. But be careful, no need to get over-active with the secateurs or trimmer.
Spring pruning often causes confusion, what to cut and when to cut it. The truth is, plants are a bit like people. Some are raring to go the moment there’s a hint of warmth whilst others need a bit more time before they’re ready to face the world.
And just like us, if you push them too early or cut them back too harshly before they’re ready, they can sulk. Or worse, they can suffer for a year or more. Plants that bloom later in the summer rather than in spring can generally be pruned now because they flower on stems produced in the current year, so we can safely cut them back now without losing any blooms.
One of the best examples of this is Buddleia davidii, the butterfly bush. If you’ve grown this before, you’ll know it can become a bit of a wild beast if left to its own devices. Don’t be afraid to be a bit brutal, cut it back hard, down to about 30 to 45cm from the ground. It’ll look drastic, but it will respond with vigorous new growth and reward you with a summer full of fragrant flowers that the butterflies will thank you for.
Cornus, the dogwoods we grow for their colourful winter stems, can also be cut back now. The bright reds, oranges, and yellows of their stems have been adding colour to the winter garden, but as we head into spring, they start to look tired.
These too should be cut hard, right down to a few inches above the ground in a process known as stooling. This encourages fresh new stems, which will give the best colour next winter. You could use these prunings as hardwood cuttings. Insert, pencil-thick cuttings, about 25cm long into the ground so that almost half of the cutting is in the ground and they will most likely root easily enough.
Roses are another group to tackle now, the key here is to cut back to just above an outward-facing bud, removing any dead or crossing stems. You're aiming to open up the centre of the plant to allow good air circulation, which helps reduce the risk of diseases like blackspot, rust and mildew. You can try to take cuttings from healthy, young rose stems, but spring isn’t the ideal time for propagating roses, better to wait until summer when you can take semi-ripe cuttings.
Fuchsia is another favourite that benefits from a spring cut. The hardy varieties can be cut back quite hard now, again to just above a healthy bud low on the plant. The new growth will shoot up quickly as the soil warms, and you'll get a bushier plant with more flowers.
Now, while we’re feeling enthusiastic about all this pruning, it’s important not to cut back everything, at least not yet. So why is it that some plants can be pruned now and others can’t?
It can all be made to sound quite mysterious and difficult to understand whereas, in fact, it all comes down to when the plant flowers. Plants that flower on new wood, like Buddleia, Fuchsia and Hydrangea can be cut back in spring because they’ll produce flowering stems in the same season and pruning will stimulate new growth, leading to a more floriferous display.
But those that flower on old wood such as Camellias, Rhododendrons, and Magnolias already have their flower buds formed, tucked away from last summer’s growth. If you cut them now, you're effectively removing their flowers or their chance to flower this year. You’ve got to let them do their thing first, and then can you can get busy with the pruners.
There’s also the matter of protection. Old growth on certain plants, like penstemon or salvia, acts as a buffer against late frosts. It might look untidy, but it’s doing a job. Leave these plants alone until the risk of frost has passed and new growth is clearly visible at the base.
All that being said, don’t feel you have to prune everything. Sometimes, a plant is best left to find its own shape. Pruning is as much about knowing and understanding the plant as it is about shaping it to our will.
If in doubt, observe. Watch how it grows, when it flowers, and what it responds to. Gardening is more about patience and trial and error than anything else.
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