Joe Swift, sensing a cold winterís on its way, zips round his London garden protecting some of his more exotic plants from the touch of frost
We havenít had a proper frost in central London for the last three years, which means that itís been possible to leave some of the less hardy plants outside completely unprotected through the entire winter. In fact, I know someone who even leaves their lemon tree outside all year round without the fear of damage. After having said that however, it is a risky game to play and it will only take one really harsh frost to destroy some plants completely. Other parts of the country are less fortunate and are assured a cold winter every year, but at least they can plan ahead, and it doesnít mean that you canít grow some of the less hardy plants, as long as enough caution is taken to protect them during the colder months. Whether protecting plants as a necessity or a caution it will also help to speed up new growth next spring.
Any tender plants grown in the ground should be mulched with a thick layer of organic material. Plants such as dahlias and canna lillies can be left in the ground after cutting back all the top growth to the ground. Itís a bit risky, and they will probably flower better next year if lifted and stored, but if you canít be bothered to store them itís worth leaving them in and seeing what happens. If they donít come back you will at least have learnt something.
Plants grown in pots can be moved to a more sheltered area of the garden. As they are in pots the root system may be susceptible to cold and it may be worth wrapping the container in fleece. I move my Agave americana and Dasylirion right next to the house where they are protected from cold winds. If you are lucky enough to have a greenhouse then move all your tender plants inside. If they are grown in the ground and arenít too big it may even be worth digging them up and putting them in pots so they can be over-wintered in the greenhouse or conservatory. If the conservatory is centrally heated the tender plants will probably prefer to be protected outside as the heating will be a shock to their system and dry them out too much.
Plants such as the banana Musa basjoo has a pretty hardy root system and can be grown outside. If you want to develop a nice tall trunk rather than having leaves come up at ground level it is this part of the plant that needs protection. Firstly cut off all the leaves so that youíre left with a single trunk. This trunk can then be wrapped in pretty much anything such as gardening fleece, hessian sacking, a plastic drain pipe (which will slip neatly over the top) and plastic bubble wrap as long as the main roots get enough water through the winter. In spring after the fear of any frosts has gone, unwrap the plant and it will quickly grow new leaves.
The most common tree fern Dicksonia antarctica is also the hardiest. Depending on how cold it gets where you are itís best to protect the crown, which is the growing part of the plant. The fronds make a vase shape, which is perfectly designed for catching leaves and debris from the jungle canopy in its natural environment. The leaves break down and feed the tree with vital nutrients. I put a couple of handfuls of old leaves into the top at this time of year, which also protects the top from frosts. You can lag the entire plant with bubble wrap or make an elaborate basket from chicken wire to hold straw around the entire crown (as I did for Alan Titchmarsh in his garden for the last programme in Gardeners World 2000).
The crowns of hardy palms such as the date palm Phoenix canariensis, Cordyline australis and Trachycarpus fortunei are also best protected in the colder areas. Tie the fronds up and together with string into a neat bunch to help keep the frosts out of the centre.
The more Mediterranean plants, such as olive trees and oleanders, are hardier than you may expect, and are easy to grow in this country. As a general rule theyíre tougher the older they get - not unlike us humans! Again if they are in a pot itís best to move them under the eaves of a building or nearer a protective wall. Even moving them under a tree or pergola will help keep the worst of the frosts at bay. They can also be protected by wrapping the entire plant in fleece, which may look silly in the garden, but will almost guarantee that theyíll still be here next year.
If we want to grow these exotic plants in our British gardens we canít expect them to deal with our cold, wet and windy weather without a bit of molly coddling. Iíve got a feeling this winter could turn really cold (weíve already had the wind and the wet), and the least we can do for our plants is make sure theyíve got some decent winter clothing to help keep them alive until the next time we see them in sunny spring 2001.
See also the Helping Hands workshops:
How to Prepare a Border for Winter
How to Protect Border Plants in Winter
How to Protect Shrubs and Wall Plants in Winter