Frost Protection - Gardening Australia (2024)

SERIES 27 Episode 14

In large parts of Australia, gardeners can expect frost on still, clear nights when the temperature drops below zero degrees Celsius. Here's how to prevent the damage.

Frost causes damage when water inside cells freezes, expands and bursts plant cells. The damage is rarely obvious until the plant thaws, because the ice holds the plant rigid.

FEATURED PLANTS

BLUE POTATO BUSH Lycianthes rantonnetii syn. Solanum rantonnetii

LEMONGRASS Cymbopogon citrates

GALANGAL Alpinia galangal

CURRY LEAF Murraya koenigii

PADDLE PLANT Cotyledon orbiculata var. macrantha

TOP FROST PROTECTION AND PREVENTION TIPS

• In the lead-up to cold weather, water tender plants with a seaweed-based solution, which will help them develop an internal resistance to frost. Seaweed solution takes about a week to take effect if you spray it on the leaves, and two to three weeks if applied to the roots
• Biodegradable frost protection sprays work by creating a protective polymer film over the leaves and stems and Sophie sprays it on upper and lower surfaces of the leaves. These sprays are called 'anti-transpirants' and also protect plants from drought, excess heat and sunburn.
• Frost protection sprays are biodegradable so should be applied monthly during cold weather - after applying seaweed solution to ensure the seaweed solution gets taken up by the plant.
• Use your microclimates to protect vulnerable plants.
• For the most special plants - like Sophie's succulent picture frame - wrap them in a protective cocoon. Any material (eg old sheets, curtains, shadecloth) will do in a pinch, there is a specialized material called 'frost cloth', 'horticultural fleece' or 'thermal control fabric'. Draping frost cloth over small shrubs and trees and securing it to the ground with bricks or such, traps heat that has collected in the soil during the day and releases it slowly at night, preventing frost formation. It can be left on for long periods, day and night, because it allows rain and about 70% of light through.