Challenge the hardiness of your plants!
In this article we briefly explain what you can do to grow plants with a higher hardiness zone-indication than the one that applies for your garden. In this way you can grow a wider selection en enjoy more plants in your garden. Plants with a lower Zone-indication should have no growing problems in your garden, unless other factors in that micro-climate affect it. For this reason we also explain a little bit more about what factors can affect planth growth.
When you buy plants, shrubs or trees often the term 'Zone' can be found on the tag that accompanies your purchase. In most cases this zone refers to the USDA-Hardiness Zoning, which (only) takes the average minimum temperatures a region will encounter. It gives you an indication if this plant can withstand the climate in your area. In Southwestern Ontario those zonings range roughly from 5a-4a in the Toronto-area / below Highway 401 (=warmer) to 4b (=colder) in the Dundalk Region, because of the altitude of that area.
There are several factors beyond pure temperatures that go into whether a plant or flower will grow and thrive in a particular region. Other important things in addition to temperature affecting plant growth are:
• heat;
• rainfall;
• frost;
• sunlight & length of day;
• altitude;
• soil types;
• day time temperatures;
• micro-environments;
• other factors, such as nutrient levels and availibility.
Within every climate zone there are small weather environments unique to your area. Even in your own back yard there can be multiple 'micro-environments' depending on:
• shade or sun;
• soil drainage (wet all the time or dry);
• soil type and condition (pH level, hard, composted, or others);
• soil cover (mulch / snow);
• shelter from the wind by windbreaks, hedges or buildings;
• hills or ridges (frost pockets);
• access to water or rain.
Refering to hardiness / the lower temperatures, avoiding winter damage to your plants is where the challenge is for your higher zoned plants. You can help to overwinter those plants by:
• Selecting appropriately hardy plants by considering the hardiness zone and their location and make use or create 'micro-climates' (see below) in your garden;
• Allow plants to harden in the fall before cold weather begins. Do not stimulate new growth by applying excessive nitrogen or pruning in early autumn. Plants that are diseased or deficient in nutrients are more susceptible to winter injury than healthy ones. Corrective measures should be taken in time so they won’t affect coldacclimation;
• Water plants during late summer and autumn to prevent them from entering the winter under drought stress. Drought predisposes plants to winter injury and cankers;
• Avoid low spots that can create frost pockets and sites that can have rapid changes in temperatures. Flowers and leaf buds can be damaged when they are prematurely stimulated to open by warm days, and then subjected to freezing temperatures at night
• Pack potted plants close together and cover them with a translucent plastic sheet that does not touch plants. Mulch or mound soil around pots and balled and burlapped plants to insulate the roots;
• Protect plants in exposed locations by wrapping burlap (no plastic!) or building a lathe structure around them.
In addition to the natural 'micro-climates' you can artificially create these. Some examples to do this are:
• plant shade trees;
• plant windbreaks, hedges;
• putting in large rocks;
• adding a garden pond;
• use of covers like mulch;
• burlap shrubs and trees during wintertime;
• and many other gardening actions to alter your area;
• use of special plant nutrients or additives (affecting pH);
USDA Hardiness Zones and Average Annual Minimum Temperature Range
|
  |