Save your garden from frostbite

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7 • POSTED ON March 13, 2005
Save your garden from frostbite
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Every Tuesday on OttawaStart, local gardener René Trim offers tips, tricks, and tools for gardening in Ottawa. This week, René talks about how to save your plants from winter damage.

One of the frustrations gardeners have to endure is spending money on a plant and pampering it all through the season, only to find out in spring that the poor thing went "missing in action” during the winter. Although it is just one of those things that happen and there is no 100% reliable solution for it, there are a few things we can do to prevent most of the winter damage.

Firstly, make sure you know how hardy a plant is before you buy it. Most hardiness zone maps place us in zone 5A with places such as Cornwall and Brockville. However, Ottawa is much closer to zone 4B - which is colder than 5A - than either of these towns. On top of that, the vicinity of a large body of water such as Lake Ontario generally has a moderating effect on the cold. Technically, we are in the same boat but chances are that a plant that survives in Cornwall will not make it through an Ottawa winter.

Secondly, make sure your plants are protected. Hard frost and wind are your plants' worst enemies, which is the reason that experienced gardeners rely on materials such as burlap to help protect the more upright of their green friends (conifers, rose bushes, etc.). Other products are available – last fall I saw something that went by the wonderful name of “Better than Burlap” – but burlap is a good and economical choice. For plants that grow closer to the soil (and remember: the lower, the colder) a cozy coating of snow – a wonderful insulator – does wonders but unfortunately, we cannot always count on snow to be there for us.

A good way to help avoid problems is to cover the base of the plant with a layer of mulch (compost is great for this purpose) in the fall. Straw or gathered autumn leaves are good too. Also, forget about tidiness and don"t cut your plants back in the fall. No one will be interested in “inspecting your garden” when it’s 25 below and besides, what is there to see? By leaving whatever is left of the leaves on a plant, you help protect them from the harshest of conditions.

Thirdly, if you have plants that you know are “iffy” in our winters, give them a sheltered spot (up against the house wall or next to a fence) rather than an exposed one. It’s all about the microclimate...

A microclimate is nothing more than the climate of a small area, such as your garden. Microclimates can vary over very short distances due to variations in the site’s topography. A simple example: the southern side of your garden will receive more direct – warming - sunlight than the northern side. As a result, the snow will have melted there, while in shaded areas it is still on the ground. By the same token, a wall, a tree or even a rock can make a difference to the temperature. Rock, concrete or brick collect heat from the sun during the day and slowly release it at night. Don’t get me wrong - it is not a 10 degree difference, but it can be enough to help your tender plants make it through the winter.

In my own garden, I have planted the plants that are “borderline hardy” close to the deck, thus providing them with a little windbreak (as mentioned above, wind is one of your plants’ worst enemies). It has not proven to be 100% effective but so far, out of seven tender specimens I have only lost two over the past four winters. One of them was an Eremurus robustus (big bucks!) and to be quite honest, I am still mightily bummed that – despite all my precautions - it didn’t make it. I guess it goes to show that even professional gardeners have their share of failures every now and again…

One of gardeners’ – as well as fruit growers’ – worst nightmares is a late spring frost. Just when the new shoots have appeared and you think you’re alright, frost strikes and kills off the new growth overnight. If you hear there is frost in the forecast – even if it’s only two or three degrees – place cardboard boxes overtop your plants. A fancier way is to use cloches but I assume not everyone will have those handy and a cardboard box works just as well. Empty cola bottles, cut in half can also double as a cloche. When there’s frost, there’s no wind, so don’t fret too much over them being blown away by the wind.

Now, for something completely different; what do you think of my beautiful Abutilon?

Those of you, who read my columns last year, may recall the Abutilon was “plant of the week” in August. It is not hardy at all in our climate, so I grow it outside in a pot during the summer season. Towards mid-fall I, literally, haul it indoors where it spends the winter in the dining room (one of the brightest and warmest rooms in the house, facing south). The transition between outdoor and indoor life is always somewhat rough on the plant; it tends to drop part of its leaves and it is advisable to give it a light pruning. After about a month, it will start to recover which is clearly demonstrated in the picture below, taken on February 22. As you can see, it is merrily blooming away, giving the dining room the feel of a patio in mid-July.

(Yeah, I know; I get a little carried away, but by now aren’t we all craving the feel of a patio in mid-July?)

Next week we will be looking into ways to improve your garden’s soil.

Until then, instead of my usual “happy gardening” let’s say” happy garden planning”!

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About René
René Trim was educated and trained in The Netherlands, before moving to Canada in 2000. After studying the differences in climate and season faced by Ontario gardeners he established Trim Garden Design and Rescue in May 2002. A gardener since the 1980’s, he has a wealth of knowledge and experience, a vast library of reference materials from which to draw answers to various garden situations as well as an enthusiastic and professional staff.