Gardening: Wrap up warm for the winter

Vulnerable plants need protection as the really cold weather begins to threaten, but you don't need to spend a fortune to safeguard your outdoor favourites

"AS THE days lengthen, the cold strengthens" is a saying I remember from my childhood. Yet, like most country saws, there is a lot of truth in it. The chances are that you will not experience a prolonged period of sub-zero temperatures until the year has turned, and the days are slowly lengthening. Now, therefore, is the time to think about protecting plants growing outside which are not bone-hardy, until temperatures begin to rise in spring.

Many people believe that this is one garden task too many, and that plants must take their chance. Either they will die, in which case you can replace them with something potentially more interesting, or else they survive and you will have been justified in doing nothing. I would never subscribe to that view. There are plenty of plants upon whose survival I do not wish to gamble. Apart from anything else, I find I can never depend on easily acquiring a plant a second time round (they have a way of vanishing from view just when I go looking for them) and the cost of many plants hardly justifies such profligacy.

Most gardens contain one or two slightly tender plants, especially evergreens, which can suffer from frost or cold wind damage. Carpenteria, ceanothus, abutilon, Cytisus battandieri, myrtle, lemon- scented verbena, and Hebe speciosa are likely suspects. But there are also herbaceous plants which we do not wish to dig up each autumn and preserve inside, such as Salvia and Cosmos atrosanguineus.

The trick to wrapping up a plant in winter is to use something that will allow it to transpire without it becoming sweaty and fungus-prone, and, if possible, also to photosynthesise once dormancy comes to an end in early spring.

Bubble wrap has the advantage of being transparent, so that plants receive some light. It is best to tuck in straw or spun fleece, then attach the bubble insulation only loosely (with waterproof tape) to the wall on each side of the plant.

Bubble pack is also suitable for protecting plants in containers. The growing medium in containers freezes more easily than soil in the border, so the roots of even hardy plants in pots are vulnerable to frost.

Straw, if available, is a good insulator but an adequate alternative, which can be bought in any garden centre, is polypropylene windbreak material. For small plants, the best material is spun fleece. It is easy to get hold of, not expensive, and excellent for protecting the crowns of tender perennials, such as Salvia patens, because it can be cut to size and tied down with pegs, or secured by soil heaped on the edges. It can also be laid in more than one layer in severe weather. This is a material that many gardeners find invaluable for protecting early sowings of vegetables in the spring or late crops in the autumn, but there is no reason why it should not have a prominent place in the winter garden - especially as it is a more sympathetic material aesthetically than black polythene. It is also just the ticket, in early spring, for throwing over a small fruit tree in flower, or a vulnerable hydrangea, if frost is forecast.

It is probably a bit flimsy for very windswept places; it is easily blown away if not well secured. Last spring, after some blustery weather, I found a portion of it hanging from a climbing rose on the house, and traced it to a vegetable garden down the street. Spun fleece rarely lasts more than one season, but is so easy to handle that it takes the grind out of winter protection. And, if the winter really comes hard, that protection could be the difference between life and death. So, in the words of another saying from my childhood: "Wrap up warm or you won't feel the benefit."