Winterizing the Garden
Our top tips for ensuring your plants survive all the elements that our Vancouver Island winters can throw at them.
Pruning
One of the best ways to prepare for the winter is to inspect shrubs and trees when they are young to ensure that the crotch angle is between 45 and 60 degrees. The crotch angle is the angle that the branch is attached to a limb or trunk. If the crotch angle is too small the branch is weakly attached and breakage is more likely. If the angle is too large the snow is more likely to build up on the limb and break it. Preventative pruning to promote good structure and strong branching will increase the longevity of the plant.
Tie Up Narrow, Upright Evergreens
Narrow junipers, yews, and other evergreens are extremely prone to splaying under snow load and the best way to minimize this is to tie the main leaders of the plant together using cloth. It is important to remove this cloth in the spring.
Windmill Palms (Trachycarpus fortunei)
Once established windmill palms will tolerate temperatures down to -12 degrees Celsius. Younger plants will do best with some protection when temperatures drop below -8 degrees Celsius. Windmill palms in containers are significantly less hardy because their roots are not insulated by the soil. Their roots cannot freeze.
What are the best ways to protect windmill palms from extreme temperature?
Firstly, palms are ideally planted in a protected location as they do not do well in cold desiccating winds. If extended periods of cold are forecast wrap reemay, burlap, or horticultural fleece around the trunk and foliage. The top leaves should be loosely tied up before wrapping. The top part of the plant should be protected by an impermeable lid to keep the rain out of the central stem (e.g. a tin pie plate, plastic yogurt lid, etc). Use a loose leaf mulch or straw to mulch the crown of the plant at the top of the soil.
If your palm is in a pot, the palm tree should either be moved to a frost-free location or the pot should be buried in the ground to protect the roots.
Trachycarpus fortunei is frost hardy so it will only need winter protection during prolonged periods of cold weather, not all winter long. If it is wrapped all winter long the risk of rot increases.
Marginal Plants
New Zealand Flax (Phormium sp.) - Mulch the base of the New Zealand Flax with a light mulch such as leaves or straw. During a cold snap wrap the leaves with reemay or crop cover. Remove after the cold snap has passed. Note: Phormium can die down to the ground in the winter and re-sprout from the roots in the spring.
Hebe and other marginal shrubs - If you are trying to push the limits of a shrub's growing zone you can place a wire cage around the shrub and fill it with leaves or straw.
Hardy banana (Musa bajoo) - Prune the leaves off of the plant and use them to mulch the base of the plant. Add extra leaf mulch to better insulate the crown of the plant. If you would like to keep the height of the banana, remove the leaves, but do not cut the stalk down. Place a wire cage around the stalk of the banana and fill the cage with leaves or straw.
Gunnera - Cut foliage off, turn the leaves upside down and make a tent-like structure over top of the buds.
Hardy fuchsia - Refrain from cutting back till the spring when new growth appears. Mulch the base of the plant in the fall.
Perennials
Many borderline hardy or mediterranean perennials benefit from having their foliage left on them all winter and having it cut back in spring, not fall. This includes:
Russian sage (Perovskia)
Cape fuchsia (Phygelius)
Penstemon
Lavender
For more detailed information on winterizing plants check out our other articles: