Winters can be very long and very cold in many northern gardening regions. Preparation for this period is vital in maintaining the survival and health of our landscape plants. This process, which can last for up to five months in some areas, is started in mid-August and can continue until the first snow flakes fall.

By late summer, the days are getting short, the sun is less intense and nights are cool and frosts can occur at any time. The plants begin their preparation for winter, as they store food reserves in the roots.

Grass, for instance, will survive better without fertilizing with high nitrogen products past mid-August. Nitrogen feeds green leaves, and at this point in the season, the plant is storing food.

By leaving the grass slightly longer with those last few cuts, you allow greater leaf surface area for production of the food, as well as increasing its ability to trap and hold snow.

A good snow cover ensures optimum conditions for survival through the harshest winters. Measurements taken at ground level under six inches of snow indicate soil temperatures to be just slightly below freezing.

To ensure that perennials, bulbs, trees and shrubs survive winter, first and foremost, purchase hardy plants. Check with your Growise Centre for the "climatic zone" in which you live. Ask for plants hardy to this region.

Removal of dead plant material helps protect plants from insects and disease that may overwinter. It is however advisable to leave plant stalks at least twelve inches long to trap snow. This is especially important in exposed areas.

Pruning is better left until early spring to avoid frost damage to cut areas. Often late winter thaws create spring-like conditions for a short time followed by a resumption of winter weather. During this time, plants may begin to come out of dormancy. They begin active growth, only to be plunged back into the deep freeze.

High plant losses are experienced during these thaws. Mulching in fall reduces rapid changes in soil temperature during thaws, keeping plants dormant until spring comes.

Also during early spring, many evergreen trees and shrubs can begin active growth, before the ground is thawed. The plant is unable to draw moisture from the frozen ground. As a result, top growth dries out. Browning of the needles and needle drop occurs.

Water evergreens deeply in fall and place "tents" of burlap or canvas around the tree but not touching the foliage. Usually they are supported by wooden stakes. These allow air flow around the branches, but reduce the drying effects of wind and reflected sun.

In areas prone to rodent (mice, rabbits) damage in winter, wrap deciduous tree trunks with a protective covering in fall. A light coloured wrap will also reflect strong rays from the sun and snow. Some trees are susceptible to "sunburn".

Many bulbs are planted in fall for spring blooming. Selections are best in early fall but be sure to choose hardy bulbs for your area. Size of the bulbs, and how cold your region gets during winter, dictates how deep they are planted. Tulips, for example, are planted four to six inches deep, while smaller muscari are two or three inches deep. Container-grown perennials can be planted up till early fall. They need some time to establish some roots in their new location. Water well and regularly until frosts kill the top growth, but don't saturate the soil. A mulch around the base of the plant will also give more protection to the roots.

Some tender roses will need extra protection to survive northern winters. Prune back stems to six inches long and cover with soil or mulch.