Head Gardeners’ tips
December 2023

The colder, darker days of December might make spending time outdoors seem less appealing but there is still beauty, comfort and joy to be found in the garden. The way the low sun backlights the peeling, flaking bark of our garden’s river birch trees, making them glow red and cinnamon, is one of the many highlights, along with the frosted seedheads of Hydrangea arborescens ‘Annabelle’, the first hints of sweet perfume from the opening flowers of Sarcococca confusa, and the emergence of carpets of hardy Cyclamen coum.

As the last of the leaves fall it’s the perfect time to review the ‘bones’ of the garden, to see the scope for development and improvement. If you’ve been eyeing up a planting opportunity on your plot now is the perfect time to plant bare root trees, hedging plants and roses. ‘Bare root’ means the plants will be supplied with no soil around their roots, they have been grown in open ground and dug up to be sent out and planted during the winter when they are dormant, which means they’re cheaper than container-grown stock and there’s often a superior choice of varieties.

One of the greatest joys in gardening, I think, is planting a maiden apple or pear tree in winter and carrying out the necessary formative pruning over the following 3-4 years to establish what is known as a ‘bush’ tree (goblet-shaped) or a restricted form like an espalier or cordon, both ideal in smaller gardens. This might sound like a dauntingly slow process but nurturing a fruit tree so it becomes strong, remains healthy and crops well is such a rewarding long-term investment – an apple tree is for life, not just for Christmas!

On deciduous shrubs and trees, you may now be able to notice dead, damaged and diseased stems that had previously been concealed under the canopy of foliage, so you’ll want to remove those with clean and sharp cutting tools. Your eye might be caught by small, bright orange raised pustules known as ‘coral spot’, which is a fungus that develops on old woody stems and isn’t anything to panic about; it usually occurs on wood that is already damaged or dead, it should be pruned out and can be minimised by following good horticultural practice whenever pruning. Going further with pruning, it’s a good time to tackle roses, fruit trees and grapevines. And remember, always clean your secateurs or pruning saw after working on a plant carrying any kind of diseased material to prevent spreading the disease.

In the greenhouse or with houseplants, it’s good practice to reduce watering as transpiration has slowed down with the shorter days, meaning compost will stay wetter for longer. If possible, it’s best to move most houseplants to rooms, shelves or windows with brighter conditions, though be careful moving anything too close to a radiator. It can help to sit houseplants on trays of gravel (or why not try something more decorative, like marbles?) with a little water to improve humidity while the central heating is cranked up. If, like me, you sowed sweet peas in autumn then they can be pinched out and moved to a cold frame so they are ready to rock early next spring. The same applies to other hardy annuals sown in autumn, move them all outside to a cold frame or against a wall where they’ll have some protection from hard frosts, to free up space in the greenhouse and reduce possible pest problems.

December is peak ‘bring the outside in’ season and this can be applied to berries, foliage and seedheads for flower arranging and wreathmaking, cutting sprigs of Sarcococca confusa for their powerful perfume, and choosing the perfect Christmas tree. If you’re buying a cut tree, it is recommended to keep it outside as long as possible, saw an inch off the base of the trunk and sit it in water. Once you bring it indoors, keep it watered and situate it as far away from any heat sources as possible. Some living spaces simply aren’t large enough to accommodate a tree but decorating a treasured houseplant, adorning some pruned off gnarly branches from the garden, or adding some miniature LED lights to an enchanted terrarium can all be done to magical effect.

Watching the birds is another firm favourite this month, so keep putting out fresh water and topping up the feeders. And to help other garden wildlife don’t overdo the tidying – skeletal herbaceous perennials that can stand up to the frosts, leaves that have fallen onto beds and borders, and piles of sticks and logs all contribute valuable habitat niches and food sources for the allies we need to predate next year’s pests.

Finally, this month I will be reflecting on another gardening year, from the cold winter into a cool spring, the early heatwave in June followed by a wet summer and mild autumn. Regardless of all the challenges and the ups and downs, I will always appreciate the generous bounty that the garden has to offer, and how fortunate it is that we are able to receive and share those gifts; it’s a wonderful gardening life.