SELECTION OF MATERIAL

A. USE OF ZONES

To help you select the proper varieties for your area, many people have devised systems of indicating zones based on climatic factors. Everybody, it seems, has their own idea of how to represent and allocate these zones. Different government authorities have devised their own zone maps. Horticultural authors, not satisfied with these, often devise their own system. To show how mixed up the present systems become, Beaverlodge, Alberta is in zone 2b on the Agriculture Canada map of plant hardiness zones; and 5b on the Alberta Agriculture map, devised by the W.C.S.H. This means that you must keep track of what system the catalogue or book is using when it mentions the recommended zones and translate this to suit the system you are using.

In 1967, the federal government collected meteorlogical data from 108 stations across Canada. This data included the winter low temperatures, the frost free periods, summer and winter rainfall, summer high temperatures, snow depth and wind speed. A complex formula was used to obtain a numerical value for each area. Based on these numerical values, the stations were designated as being in a zone ranging from 0 to 9, which were further subdivided into A and B groupings. A map was drawn up to indicate the approximate extent of these zones and is available from Agriculture Canada.

The Prairie Provinces have another system of zones. In 1953, the Western Canadian Society for Horticulture published a zone map for the prairies based on the length of the growing season, average precipitation and the temperature range. This map is used in the Alberta Horticultural guide which is available through Alberta Agriculture. The zones on this map do not relate to the federal map in any way at all.

The zone map used by the U.S. Department of Agriculture covers a portion of Canada and is used in most American publications. Because Alaska was not included in the zone map, Alan C. Epps, Natural Resources and Land Use Planning Specialist with the University of Alaska, devised his own zone map based on the same criteria. His system is used in many publications for Alaska.

Some of the Atlantic Provinces have also devised their own zone map for their area.

Now, to add to the confusion, many nurseries do not use any zone system to aid their customers in their selections. Some, such as McFayden, invent their own system to confuse the buyer even more. Those catalogues, such as Sheridan Nurseries, who do include the Agriculture Canada zone map, do not print the entire map. They tend to think that the north is unsuitable for growing plant material and omit this area to save space in their publication. They do not realize that the northwest area of Alberta and British Columbia are farming areas and quite suitable for a wide variety of plant material. This area includes the cities of Grande Prairie, Fort St. John, and Prince Rupert, as well as their surrounding towns and villages. This is a fairly large population of potential buyers that most publications overlook. Note: part of this problem has changed since this was written.

One problem arises when selecting plant material using the zones. Many people feel, because of inherent genes, that if one plant of a specific specie or cultivar survives in a zone area, that all plants of that same specie or cultivar will also survive. In St. Paul, Minnesota, in tests using Cornus stolonifera (Red Osier Dogwood) it was shown that this was not true. These dogwoods were collected from widespread locations in North America and grown in one location in St. Paul. All became hardy enough to withstand the winter temperatures, eventually, but plants native to milder climates were often partially killed back by the fall and winter frosts. They did not acclimatize soon or fast enough. Thus it can be shown that if the plant material is propagated in a climatic area similar to that of the purchaser, it will have a better chance to acclimatize and suffer less kill back. This may not be important for shrubs, but for trees, the damage could permanently mar the natural form of the plant. One should always attempt to select plant material from a source with a similar climate, if possible. Often, though, you have no choice as local nurseries do not always propagate their own stock but buy it from a wholesale nursery located in a more favourable zone. If more northern nurseries began propagating a wider variety of plant material, this problem would be overcome.

B. USE OF BOTANICAL NAMES

Another aid to the selection of plant material is through the use of the botanical names of the plants. There is no standard in regards to the common name of a plant. There are several plants that go by the same common name. The Flowering Plum is a good example. Prunus triloba and Prunus triloba 'Multiplex' are two plants listed as Flowering Plums in the catalogues. They are both hardy in zone 2. Prunus glandulosa and P.G. 'Sinensis' are two flowering plums hardy in zone 5. Without the botanical name, the customer does not know which to buy for his zone.

C. USING GARDENING BOOKS AND PUBLICATIONS

When selecting plants for the landscape or orchard, many people turn to gardening magazines and encyclopedias. Most of these were written with the American market in mind. Even those written for Canada only briefly touch on the northern areas and their specific problems. There was considerable literature put out by Agriculture Canada on the north in the past but most of this literature is either no longer in print or mentions varieties that are not available today. Many times it is impossible to obtain information regarding specific problems of the north. Government publications should be updated and reissued to provide the northern gardener with the information he requires. Some excellent books have been written by people who live and garden in the north, but they do not have a wide distribution. Much of the data in them was obtained from both government research and personal experience. A listing of some of the publications will be included in the Appendix.

D. USE OF NORTHERN VARIETIES AND CULTIVARS

There are many vegetables developed for northern conditions. From Alberta came the Sub Arctic series of tomatoes, Limelight beans, and Earligold melons. From Manitoba came the Prairie Pride and Ping Pong tomatoes, Harper Hybrid melon, Early Arctic corn, Morden Early cucumber, Supersweet peas, as well as the Pee Wee, Little League, Junior and Morden Midget cabbages. A cooperative program between the provinces resulted in the Starfire tomato and the Far North melon. From Alaska came the Alaska Frostless and Alaska Red potatoes. These two potatoes have frost resistent tops and deep tuberization that requires no hilling. A problem in the north caused by the extra long daylight hours has been the bolting of spinach and beets. Boltardy beets and Marathon spinach are not subject to this premature seed production.

There has been much research to develop hardier cultivars of trees, shrubs and flowers for the landscape, as well as hardy fruit trees for the orchard. The list of these is too extensive to include but include many plants developed or selected at Morden, Manitoba; Brooks, Alberta; and Ottawa, Ontario.

E. USE OF EARLY MATURING SEED VARIETIES

When selecting seeds for the garden, one has a slight advantage over the landscaper. Many catalogues list the days to maturity of the different varieties. This gives an approximate idea of the length of time required to mature this particular variety but this can be varied by several other factors, including the length of day. By comparing the different varieties with one you already grow, you can get a fairly accurate picture of whether your season is long enough to grow the others. A more accurate way of measuring time to maturity is using Growing Degree Days. This is the number of heat units or growing degree days and is based on the fact that plants must have a certain amount of heat to make any growth. Sunlight alone cannot ensure growth and therefore maturity of the plant. Most cool season plants require more than 42°F (5.6°C) to grow. This figure is used as a base and is subtracted from the mean temperature for the day to give the growing degree days. The amount of growing degree days (Heat Maturity Constant or HMC) is not available for all varieties as yet but will provide a guideline in selecting varieties when the data is known. An accumulation of 1,000 growing degree days is considered the basic necessity for dependable production of frost hardy vegetables. An example of the benefit of knowing and using the HMC can be shown easily. Ottawa Ontario has only 138 frost free days but more than 2,000 growing degree days. Sidney B.C., on the other hand, has 230 frost free days but only 1,900 degree days. This accounts for why sun loving plants such as corn prefer Ottawa despite the shorter season.

F. CHOOSING PLANTS IN REGARDS TO THEIR CULTURAL NEEDS

Plant material for the north should be chosen carefully. Plants that are very tolerant of adverse conditions will survive well but many plants have explicit needs in regards to exposure, soil type and pH, water requirements, and winter protection. Plants must be chosen taking into consideration all factors of the site, the type of care you will be able to provide them, the desired effect, the cost of providing for their requirements, etc. Some plants, such as cherries, are very susceptible to sunscald and other winter damage caused by exposure to the harsh winter sun and reflection of the sun off the snow. These plants must be given extra protection in the form of wraps, screens, or by planting on the north or east side of a shelter. Other trees need shelter from the north and west winds. It is no use planting material that requires winter protection if you have no intention to provide it. You will be throwing your money away. Do not choose a plant just because your neighbour grows one. By using references, you will find just the right plant for your needs. A flowering cherry may not be hardy in your area, but there are many flowering crabs that rival the spring beauty of the cherry.

G. THE USE OF NATIVE MATERIALS

In zones 1 and 0, quite often the only plant material available is native plants. Native trees and shrubs will make good landscape material if moved when young and given proper training and care. Judicious pruning and fertilization can improve the appearance of a wild tree considerably. Some "imported" material will survive in these extreme northern areas. For instance, in Yellowknife (zone 0), Prunus padus (Mayday Tree), Flowering Crabs, Mountainash, and Weeping Birch have been grown successfully. Shrubs such as Ural False Spirea, Potentilla, Cotoneaster, Caragana, Lilacs and Mockorange have been grown in zone 0, when given reasonable care.

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This page by Pat
updated August 18, 2000

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