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Nursery Notes: Stress helps shrubs develop fall colour

If you want colour on your shrubs before heavy frosts come, try giving them a few weeks of drought stress at the end of August...
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Evan Davies owns Beltane Nursery at 2915 Highway 3 in Erickson.

Fall still sees a lot of folks with inquiries at the nursery. I would say that by far the greatest volume of enquiries this week went something like “What’s that bright red shrub we are seeing all over town?” To answer, it is the dwarf winged burning bush. It grows to five feet tall and perhaps six feet wide over 15 years. You can prune it anytime to keep a more compact shape. Deer will do that for you, and because you aren’t trying to have it grow any flowers there isn’t any real harm. They are fully hardy on this side of the Rockies and will grow in protected spots in Alberta if you wish.

The other day, a gentleman stopped by with a sprig of green burning bush. His concern was that his newer shrub hadn’t developed any fall colour two years in a row and he was somewhat upset. I asked him where he had it planted and if it was being well looked after. It was planted in a good garden soil and growing quite nicely in a bit of shade.

Here is the deal. Fall colour will develop on plants that are stressed out earlier than on happy plants. I like to point out that you often see bright red burning bushes on some dry corner of a front yard in town. You notice them first because they turn colour first. They went dry back in August and started to shut down for winter early. Plants that are well cared for keep growing longer into the fall.

In the past I’ve written columns on the science of why fall colour develops, so I won’t bore you with it again today. I wish only to say that the underlying colour of a plant shows through in fall when the green chlorophyll in the plant leaves begins to die off. It is wise to give a new plant a few good years of care for establishment before letting them grow on their own. In any case, if you want some colour on your shrubs before the real heavy frosts come and knock all their leaves off, try giving them a few weeks of drought stress at the end of August. Alternatively a mechanical stress, such as root pruning — chopping off up to a third of the root system with a spade — should do the trick. Chop, chop. That is some instant plant stress.

Besides the burning bush, there are many other shrubs that will give you excellent fall colour. Blueberry bushes give great colour and fruit, as well. Barberries have awesome fall colour and little thorns that make them deer proof, too. And Spireas, fothergilla, beautybush, smokebush, cotoneaster, witchhazel, sumac and vibernums of all kinds, to name a few more. There really is no end to the possibilities given the diverse range of plants that we can grow here in Creston.

Evan Davies owns Beltane Nursery at 2915 Highway 3 in Erickson.