ARTICLES
Introduction
Planting
Colour
Springtime
Tulips
Catalogues
Seeds
Books
Weeds
Articles - Springtime
Hardiness zones
The weather has been so weird this winter that I've been thinking about what, or even if, we should be concerned about hardiness zones. It may be old news to many gardeners but others find this a confusing subject. And no wonder -- some plants are allocated to different zones in different places. You get the feeling that it's pretty arbitrary in a lot of cases.
Let's start with a rough definition: A hardiness zone is an area with similar average low temperatures and number of frost-free days. There are certain plants that grow well within its range. Each garden, depending on how protected it is, usually has many different zones of hardiness within its confines. The kind of soil, moisture, weather patterns of the area all make a difference.
There are two hardiness zone maps you might see in catalogues. The Canadian zone map is divided into cold and warm sections of any given zone (a and b respectively); factors such as altitude, wind and precipitation have been taken into consideration. The other is the American zone map (there are several but the USDA is seen and quoted most often). The legions of Canadian nurseries who buy their stock from the US would like zones to be consistent continent-wide. But the defenders of the Canadian map can get apoplectic on the subject -- they feel our map is more useful. You and I get caught in between.
I've pushed lots of plants beyond their listed zone in my garden and most gardeners do this whether they are aware of it or not when they experiment with new plants. A shrub may languish and then about Year Four bounce into life because it has become acclimatized to its site.
This is true for most woody plants -- the trees, shrubs, vines or anything with obvious woody stems. Most herbaceous perennials (the plants that disappear all winter) will be protected by snow cover or deep mulches in areas where there's a freeze-thaw cycle that may expose them to brutal weather. Quite often you can just ignore the zone designation of these plants unless you're trying to grow a Z8 perennial in Z3 and clearly you'll need an annual replacement.
For instance, two brilliant catalogues arrived this week: The Plant Farm from Salt Spring Island, BC and Lost Horizons from Acton, Ont. I was going crazy with excitement when I saw Plant Farm's Z6 plants I was sure I could never grow listed. That is until I read that these were actually USDA numbers. Add a zone and you get closer to reality. I still won't be able to grow Corylopsis spicata, Lonicera nitida 'Baggesen's Gold' and Stipa tenuissima. Even so I'm tempted to give them a try. This is clearly an adventurous nursery.
Lost Horizons is located in Acton, Ont in an area with little reliable snow cover, and subject to freeze-thaw cycles as are most of us in Southern Ontario. They grow and trial plants under difficult circumstance which makes them extremely hardy. And quite reasonably its owner, Larry Davidson, says they are just "general guidelines." He has 400 new plants this year and I'm ready to toss a bunch of old ones just for the pleasure of trying some of them. Have a look at the amazing pulmonarias, lobelias and primulas he's chosen. This is such a literate read.
And about that weird weather: well there's nothing much we can do about it. If you have mulch you can spread it around the bulbs that are coming up much too early and hope that it keeps the soil temperature even. Apart from that, pray for an early spring so all those buds won't get blasted.
I highly recommend both these catalogues: Lost Horizons, RR#1, Acton, Ont. L7J 2L7; The Plant Farm, 177 Vesuvius Bay Rd., Salt Spring Island, B.C. V8K 1K3, $2.
Coming up next week is the marvellous Canada Blooms show at the new Metro Toronto Convention Centre. This show was a smash hit last year and it promises to be even better this year since it will not only be larger and more lavish, it will also be accessible by public transportation. Shuttle buses run from Union and St. Andrew's Station; there's parking on Queen's Quay with a shuttle every 20 minutes. The show runs from March 11th to 15th, 10 a.m. to 10 p.m. (To 6 p.m. on the 15th). Tickets available at the door $10 / $9 and kids 10 and under, free; 2 day passes $15. Call 416-593-0223 or 1-800-730-1020 for more details.
Copyright Marjorie Harris, 2005
CONTACT MARJORIE HARRIS
link to native plant nurseries & info Evergreen