What to do in the garden in December
Winter gardening videos
How to overwinter tender plants and how to overwinter seeds so they are good for the next year
Prevent Wind Rock in Roses
Wind rock can be a problem for roses, especially for the taller varieties. Strong winter winds can cause the rose to shift about in the wind, which creates a gap between the stem and the soil. This gap can get bigger as the plant moves about in the wind, which allows water in around the stem, and then to freeze. It is possible to reduce the plant's vulnerability to "wind rock" by pruning the stems down by around a third. Only prune roses during a mild spell, otherwise it is possible the frost may damage the growth bud below the cut and cause die back of the stem.
Prune climbing roses
Besides dealing with "wind rock" if there is a mild spell you can prune climbing roses. Shorten side shoots by two-thirds and remove old branches which should create new growth from the base in the spring. Tieing in horizontal branches will further protect it against the wind.
Prevent water butts freezing
If there is a prolonged spell of low temperatures and freezing weather, it is possible for the water in a water butt to freeze, and this expansion will cause the plastic to fracture as in the image left. I took this image, and it is exactly what happened in my garden during a spell of very bad weather. To avoid costly repairs, drain your water butt if severe weather is predicted.
Protect non hardy plants
Non-hardy plants require winter protection; follow this link for an explanation of Frosty Hardy.
To ensure winter survival, it is best to bring the plants in under glass, or at least to the shelter of a wall and raise the container so it is off the ground by inserting feet or raising on bricks. If overwintering outside, it is important to wrap the container with something insulating, bubble wrap, Hessian, or old jumpers and if it's going to be freezing, cover the plant with a fleece. It is equally important to remove the fleece when the cold spell finishes to ensure the plant gets plenty of air circulation.
Plants covered all winter, or covered up for too much often get damp, which can cause rot.
Many plants which are not fully hardy will survive in an unheated greenhouse provided it is dry. Winter wet and dampness, which causes botrytis, will damage or kill a plant. It is important to keep borderline hardy plants dry.
Weed Borders and Thin out Forget-me-nots
Winter can be a good time for weeding. I often find that by summer's end, I've lost the battle against the weeds, especially because lush plants hide them until it's time to clear the borders. After a frost is a good time to weed; the ground yields the weeds more easily.
It is good to look forward to Spring and Forget-me-nots (latin name Myosotis) often get a bad press as a zealous self seeding cottage plant. Bad press or not, forget-me-nots can offer much welcomed early spring colour and look fantastic with spring bedding and in a natural setting alongside a stream in a semi wild patch.
For the best spring display of Forget-me-nots, during a mild winter spell, thin out the plants. Forget-me-nots do self seed a lot, and if they are growing too close together, they are prone to mildew which can spread to adjoining plants. One year I didn't thin them out, and they overcrowded other plants, and damaged a clump of Hellebores. It really is important for the health of the forget-me-nots and the surrounding plants that you thin them out in late autumn or early winter.
Prevent Damage to lawns
It's true that walking on the frost frozen grass can cause damage. When frozen, the leaves become brittle, and will not yield to pressure, which means when trodden on, they snap and break. The image shows the damage from walking on the grass; brown marks where the grass is damaged look unsightly in the spring, and the damage makes that patch more susceptible to disease.
Given how hard it is to create a decent lawn it's worth resisting walking on it during the very cold weather.
Watch out for snow damage to shrubs
It is a good tip to knock snow off shrubs when there has been a heavy snowfall. I used to think this advice represented an abundance of caution, making gardening work for work's sake, until we had a bad winter with heavy snow and it badly damaged several shrubs. All shrubs are at risk, but those with the more open crowns are most at risk. What happens is the snow piles into the open centre of the shrub, which forces the branches out until they snap. Also, the snow weighs down the branches, freezes them to the ground, bending branches over until they snap.
Heavy snow will snap the branches of even mature shrubs. If this happens, all you can do is prune the shrub, but it may never regain its shape if severely damaged. A good tip for snowy weather: get out there as soon as you can with a soft broom and brush snow off the tops and loosed branches tied down by snow which will save the shrub, and money if you have to replace it.
I photographed this Elaeagnus in my garden; snow damage devastated it, and I had to prune and cut away many branches. The sheer weight of the snow had bent the branches. Some touched the ground and held down by the snow, and more snow. Finally, the branches snapped, even mature branches, leaving me with no choice but to cut them off completely; snow pruning a novel experience. Snow is far more destructive than it seems. The short video below shows the effects of snow and how to deal with it to avoid problems.
Hellebore black spot
Hellebores can look unsightly with black spot. It is fine to cut off old leaves from Helleborus, which produce flowers from ground level, to expose the flowers and remove the leaves infected with leaf spot. It is best not to compost the removed leaves because of the black spot infection.
Hellebores are a lovely late winter and early spring flowering plant which are easy to grow and will tolerate some shade.
Tips on growing Helleborus and images of many varieties of Hellebore and some "before and after" images showing how much of the Hellebore leaves you can safely remove.