IN THIS ISSUE: Perennials for Fall and Winter Interest Lakewinds - Bed & Breakfast & Garden!
 Does your Orchid need a Crackpot? Readers Q & A

Is this winter? Am I writing for the spring issue of In Leaf? The weather in Niagara has been so unseasonably mild, I'm not sure what to think. Our landscape crews worked right until December 24th this year! We had a little snow around Christmas time, but before and after that, it's been nothing but tropics north here.

‘Tis the off season for us now, but we find this a very busy and important time to prepare for the coming year: designing garden plans, finding new products, updating our website, developing our calendar of events, creating our display for Canada Blooms - which reminds me, March 13th through 17th, 2002 are the dates for this wonderful show. You'll find us at booth #908, if you want to stop and visit.

I want to thank those of you that have shared your comments for In Leaf. We continue to receive positive feedback and we appreciate all of your suggestions. Our goal is to offer timely and "botanically correct" information with every issue. Please keep your input coming, which helps with our ongoing commitment to this publication.

In this issue you'll find out more about the effects of winter on plants, exploring vines to enhance your garden, housing our feathered friends, along with holiday decorating tips from our staff gardeners (or should I say staff elves!).

All the best to you and your garden in 2002.

Michael Schmahl
Editor-In-Leaf

How does the winter weather affect the garden? Every single element plays a role in determining how much damage plants are going to experience as a result of the winter. Most often the lowest temperatures are scrutinized and blamed for real or misdirected damage. Getting away without blame, the wind also plays a significant part in causing winter damage. Also, many gardeners do not stop to consider temperatures that creep above freezing are also very damaging (particularly to broad-leaved evergreens). Winter damage can also be caused indirectly by the weather when snow load and freezing rain breaks branches. Other causes beyond the weather should also be considered. Salt spray or melting water laden with de-icing salt can cause damage to plants close to roads or walks. Knowing how winter affects the plants in your garden is the first step in the strategy to winning the battle.

The best protection from most of these winter hazards is to have a frequent blanket of new snow. A continuous snow cover will be very good help to insulate many plants (particularly those on the north side of the house, wall or building) against low temperatures, salt and ice to some extent. Since moving to a snow belt area is usually not an option, use the snow that falls wisely and encourage it to stay. Carefully shovel snow onto perennials, evergreens or shrubs that need extra protection. Build snow fences to cause blowing snow to fall on garden beds. Pile evergreen boughs and other materials that will trap the snow in crucial areas.

Most of the visible damage from winter weather is in the form of windburn. Broad-leaf evergreens like Photinia fraseri, a shrub called Christmas berry, often looks like someone placed each leaf in dry ice. Any winter weather damage is somewhat expected when this plant is growing "outside its hardiness zone" in the colder parts of Niagara. The resulting brown leaves are not unexpected as some books call it a zone 8 plant and particularly if it is not protected in any fashion. The good news is that its dormant buds are often very healthy and will open with new fresh foliage in the spring.

Usually many more evergreen plants suffer winter burn from the drying winds than any other type of garden plants. This happens because evergreen plants continue to transpire (give off moisture) during warmer winter days. The damage appears when the plant is transpiring more moisture than it can replace. The critical times for damage are when the air temperatures are above freezing and the soil is not. If the water in the soil is frozen, then plant roots cannot replenish this lost moisture and the leaves start to brown. Silver thyme (Thymus argenteus), thymeleaf cotoneaster (Cotoneaster microphyllus 'Thymifolius'), and Oregon grape (Mahonia aquifolium) often have
damage to their leaves because of this situation. The damage is not too much of a concern for plant health reasons. Many plants damaged by winter burn can be trimmed back with hedge shears to remove the burnt leaves. Often plants will grow vigorously and replace these lost parts soon in the spring. The Oregon grape and cotoneaster, in particular, will send out a new healthy set of leaves in the early spring to hide any damaged leaves.

Many other somewhat tender plants may look like they have come through the winter without damage. A nagging worry that cannot be dismissed is the concern that some winter damage may not show up during or even at the end of the winter. Many plants that look very healthy now may be suffering winter damage and might not make it through the summer. Occasionally plants will succumb to winter injuries when they are under the first big stresses of the growing season. This additional stress in itself usually does not cause major harm. Adding the stress of the first hot spell or the first major drought of the season to the invisible winter damage could be enough to kill some plants. If a plant is suspected of being damaged this winter give it some TLC in the months ahead.

Low temperatures are a very measurable figure that can be used somewhat easily to produce a plant hardiness map. These zone indicators are a quick and easy way of determining if a plant is hardy to your zone without having to use the "trial and error" method. These hardiness zones are good guidelines to stop some gardeners from gambling on the survivability of plants and committing planticide. Hardiness zones are not 100% accurate because there are limits to the types of data that are being used to create them. Weather recording stations are usually placed in an open field for accurate collection purposes. Most gardeners prefer not to spend too much time gardening in this situation. Even new neighbourhoods have buildings to give shelter. So planting a garden for a warmer zone is often done (particularly if a microclimate is present).

Microclimates play a big role in modifying the weather patterns of most gardens. Garden temperatures may be colder or warmer because of a proximity to hedges, buildings, water, or city. The closer a garden is to a city or large body of water the warmer it is (and often the more snow it receives). A change in elevation or placing a garden in a valley creates a microclimate that produces different weather patterns. Pockets of protection allow gardeners to grow plants that should not survive their area according to the information found on many hardiness zone maps. Growing "out of the zone" and fooling Mother Nature is a pastime that many gardeners like to undertake. Chances for plant survival are higher if gardeners look for protected microclimates in which to grow plants that should not normally survive.

There are more factors that affect plants than the obvious minimum lowest temperature during the winter. The duration and timing of unusually low temperatures is also a factor. Plants can survive lower temperatures if they are fully hardened off. This means that plants that go through a gradual reduction in temperature will be better able to survive than those plants that receive a sudden cold snap in the early fall. Late winter can also be hazardous to plants. Plants that are perfectly hardy during a series of minus twenty-five degree nights in mid-winter may be damaged in early spring when the temperature is only minus five. To explain this damage, it must be understood that the plant has started to come out of dormancy and has lost some of its cold hardiness. For this reason, cold temperatures in early spring that appear mild compared to the middle of winter can also do significant damage.

Plants that are under stress from improper placement are also more likely to succumb to winter injuries or death. The wrong soil type, light levels, nutrient level, pH, or water frequency all put a plant under stress and make it less resistant to low temperature and other winter weather damage.

Genetics also play a part in cold hardiness. Two plants that are the same species and that look alike may have differing degrees of winter hardiness because of a difference in genetic inheritance from their parents. Just as the survival of the fittest is the law of the animal kingdom, the same is true for plants.

It is important to realize that hardiness is based on more than weather records that tell the story of the average minimum or maximum temperatures. Soil types, exposure, rainfall, humidity, proximity to windbreaks, soil moisture, snow cover, winter sunshine, plant types and the age of plants all contribute to survival ability. Being able to understand all these factors is a valuable skill in caring for plants in the garden.

Anne Marie Van Nest is a graduate of the Niagara Parks Commission School of Horticulture, where today she is also an instructor.
Anne is a member of the Garden Writers Association of America and the garden columnist for The St. Catharines Standard.

 

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