Frost, or more specifically, the alternate freezing and thawing action of frost, can destroy plant cell walls which usually affects young plants or new, unhardened, growing tips. Flowers, buds, shoots or leaves of hardened plants may also blacken or become distorted and in severe frosts the bark of woody plants can split. Damage is more likely to be seen on tender plants, particularly those what have put on growth in late autumn or early spring but can also be seen on variegated or gold leaf plants.
Always select your plants carefully and give consideration to the placement of plants that are frost tender. Avoid frost pockets where cold air might settle such as the bottom of a slope.
There are some steps you can take for your frost sensitive plants to reduce the frost damage. Spraying with Vaporgard at least 3 days before a frost will act a bit like a liquid frost cloth. Providing up to 3 months worth of protection from frost. Respray any new shoots. Of course you can also drape frost cloth over frost tender plants where feasible but remember to remove the frost cloth for the day, don't leave it sitting on your plants.
Avoid using nitrogen rich fertilisers toward the end of autumn as this encourages new growth which will not be able to harden before frosts occur.
When frost threat is over prune out any damaged growth, cutting to an undamaged side shoot or bud. Delay pruning if frost is still possible, leaving it till the weather warms up. Remember to feed your plants after pruning to encourage strong new growth.
Wairere Nursery 826 Gordonton Road, R D 1, Hamilton 3281 Ph: (07) 824 3430 Email: