Dormant spraying is an effective preventative measure to control insects and diseases in the home garden. Dormant spraying means that it is applied before leaves appear. Horticultural oils (often called dormant oils) are primarily useful for insect control. Lime sulphur will prevent many common diseases.

Dormant spray kits are readily available in garden centres and make the task of mixing and spraying rather easy. Kits usually contain a Lime Sulphur Solution and a smaller container of Dormant Oil Spray. The quantities reflect the concentration of the mixture which you will be required to make. One kit (containing 1L of Lime Sulphur and 250ml of Oil) will be enough to treat about 5 trees or 10 shrubs.

Dormant sprays control a broad spectrum of pests and are relatively safe compared to synthetic pesticides. Oils and lime sulphur are two examples of pest control products which were used prior to the development of synthetic pesticides, as early as 100 AD. Today, they are gaining in popularity in commercial horticultural operations (such as orchards) as growers look to alternatives to pesticides for pest control.

Dormant oil works by suffocating the eggs or overwintering stage of insects. Oil is considered a "contact insecticide", which means that only the insects present at the time of application will be killed by the spray. Insects which migrate to the treated plant will not be affected by oil residues. This is good news for beneficial insects such as lady bugs which generally overwinter as adults in clusters, in leaf litter or other sheltered areas.

Lime Sulphur works by killing the overwintering fungus which cause disease.

Dormant Oil and Lime Sulphur are safe to use on dormant fruit trees, roses or deciduous trees and shrubs. Evergreens may be damaged by the spray due to the reflection of the sun off the oil causing leaf burn.

The pests that can be controlled by dormant sprays include mites, aphids, pear psylla, scale, black spot and rose canker. Honeysuckle aphid and euonymous scale are two common garden pests which may be easily remedied by dormant spraying.

Select a mild day in early spring, prior to bud break, to do your spraying. The temperature is more critical for your own comfort than the effectiveness of the spray. Wet all of the branches and twigs with the oil-lime sulphur mix until it sheds drops. Lime sulphur will stain concrete and clothing so be sure to protect non-target areas which may fall in the path of the spray. Treat yourself to a decent hand sprayer, and keep it only for dormant spraying, and you will be glad you did. The $30 investment is well worth it!