How does frost actually damage plants

A. In freezing temperatures - generally accepted as 32oC and below - water inside the plant freeze and expand which can eventually rupture the cell wall. The effects can vary from causing 'burning' the tips of a few leaves (turning them brown and thin at the tips), to do so much internal damage to the structure of the plant it dies altogether.

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A.� Hard persistent frosts that stay around for days or even weeks, like the infamous freeze of 1986-87, can be fatal even to plants generally considered hardy (cold resistant).

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However, during an average winter it is not necessarily the hardest frosts during mid and late winter that cause the problems but the early and late ones. Early frosts, which typically arrive from late September to early November depending on whereabouts in Britain you live, are a worry because they can effectively catch plants unawares. Although many plants naturally adapt to colder temperatures during autumn and early winter an early frost can hit them before they are fully ready.

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A.� Look out for signs of blackening or withering of previously healthy shoots. With larger of well-established plants the signs of damage are often found on the extremities such as brown areas on the leaves and shooting tips of buds.

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A.� Cold air sinks, so generally low-lying areas like the bottom of valleys are prone to heavier frosts than higher ground. Within the garden itself walls and fences can trap the cold air behind them creating localised frost pockets.

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A. To protect freestanding shrubs wrap them in horticultural fleece, making sure to secure it all the way round to prevent it being blown away. Bubblewrap or even an old blanket will do as a temporary measure, but shouldn't be left on for long periods as they prevent the plant from breathing.

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Wall trained shrubs and tender climbers can be protected in the same way, perhaps with a layer of insulating material like straw.

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