First Published 7/29/2004
Hedges

On the Prairies, when we think about hedges, it’s the cotoneaster that first comes to mind. And while the cotoneaster looks great and responds well to pruning, it’s not the be-all and end-all of hedges. There are many other choices to explore.

Choosing a Hedge

If you’ve decided to plant a hedge in your yard and you want to venture beyond cotoneasters, the first question to ask yourself is whether you want an evergreen or deciduous hedge. Evergreen hedges are great for year-round greenery, while deciduous hedges provide privacy during the summer yet allow sunlight to pass through during the winter, brightening your yard and home. Of course, deciduous hedges lose their leaves in the fall, and some of their appeal goes right along with the foliage.

Formality is another important factor to consider. Do you prefer a dense hedge that can be pruned into a formal shape, or do you prefer an informal, more open, coarser growth habit? Leaf size and texture and branching ability are important for determining which plants are suitable for which purpose. The smaller-leafed and more vigorously branching plants are the best choice for formal hedges.

I chose to plant Techny cedars in my backyard for year-round green foliage. Techny cedars are a little coarser than many cedars, but they’re also tough, thick, respond well to trimming, and are not prone to insect or disease problems. They create an ideal privacy screen.

You may prefer a plant at the other end of the scale, the boxwood: not the English type, which isn’t hardy here, but the Korean boxwood (cultivars of Buxus microphylla). It’s a very slow growing evergreen hedge, very short, with small leaves rather than needles. It’s great for highlighting beds or other features in the garden, but it’s far too short for privacy screening.

Another Option

One plant you’ll be seeing more of in the future is the barberry. They’re not common in our region right now, mainly because the species types harbour wheat rust – not a great feature on the wheat-rich Prairies. Fortunately, none of the new ornamental barberry varieties available at garden centres are hosts to wheat rust, and they’re finally finding their way into Canadian gardens.

Barberries serve as outstanding specimen plants, and they also make incredible hedges, whether you’re using the rich, variegated, burgundy ‘Rose Glow’ or the bright yellow ‘Sunsation.’ Barberries do produce rather sharp barbs, so it’s prudent to wear thick gloves at pruning time.

Shade Hedges

Shady spots are always challenging, but provided the light levels aren’t too low, both the wayfaring tree Viburnum lantana and the highbush cranberry Viburnum trilobum make excellent, shade-tolerant, deciduous hedges.

The Right Frame

There are many other outstanding hedge plants available today, including pygmy caragana, dwarf lilacs, alpine currants, and many varieties of cedars. (I’ve even seen excellent hedges comprised of larch and spruce, definitely non-traditional hedge plants!) Each has its own strengths, so investigate their growth habits and foliage colours before you make your decision. Hedges are much like a framed and matted work of art; regardless of the beauty of the painting, it’s just not the same without the right frame.

First Published 5/27/2004
Non-Stop Begonias

When it comes to hanging basket plants that provide outstanding season-long colour in the shade, begonias are tough to beat – particularly the spectacular Non-Stop series.

Begonias are indigenous to Peru, Bolivia and Ecuador, and were brought to North America in the mid-1800s. To date, 1200 begonia species have been identified. Of particular interest to gardeners is the outstanding Non-Stop begonia series, Begonia x tuberhybrida, the product of years of breeding work. The Non-Stop begonia has become the quintessential plant for shade in Canadian gardens.

Flower Shower

“Non-Stop” is an excellent name for this series of begonias; they bloom continuously from spring until the first killing frost in the fall. The blooms come in a surprisingly wide variety of vibrant colours, including yellows, pinks, oranges, and reds. The flowers are also interesting in a botanical sense; begonias are monoecious, meaning they produce separate male and female flowers on the same plant. The big, showy double flowers are male, and the small, single flowers are female. The female flowers typically border the male flowers and some gardeners prune them off, the theory being that the plant will divert more energy to the male flowers. Personally, I haven’t noticed an increase in the larger, male flowers after such pruning, so I just leave the single flowers on the plant. Besides, they’re attractive in their own right.

Care & Nurture

In general, begonias are light feeders, so don’t overdo it with the fertilizer; I’ve found that a applying 20-20-20 at half the rate on the label is plenty for begonias. Watch the leaves: if they start to curl downwards, that’s an indication that you’re applying too much fertilizer.

As for watering, the non-stops are surprisingly tolerant of dry soil, but I don’t recommend letting them dry out; tolerance is one thing, performance, another. Begonias stop flowering and the foliage develops a bit of a grey hue when the soil dries out. However, they do bounce back with the return of proper irrigation.

While begonias are semi-tropical to tropical plants and therefore have no tolerance to freezing temperatures, they endure spells of cool weather remarkably well.

When it comes to sunlight, even a few hours of afternoon sun will cause the leaves to become much smaller and thicker than the same begonias grown in semi-shade.

Performance Issues

When non-stop begonias fail to establish quickly after transplanting, the problem often originates at the greenhouse. When begonias (or almost any other plants) are crowded in the greenhouse, the plants become lanky and stretched as their leaves struggle to compete for light. Stretched plants have weak, floppy stems, easily damaged by wind and more prone to insect and disease attacks.

One such disease is powdery mildew, a debilitating fungus that shows up as unattractive white spots on begonia foliage. Powdery mildew is probably the most common pest of begonias. Once it becomes established it spreads very quickly, turning leaves a ghostly white. Fortunately, the Non-Stops are more resistant to powdery mildew than many other types of begonias.

Contrary to popular belief, watering the leaves doesn’t increase the incidence of powdery mildew, which is fortunate, since it’s virtually impossible to water begonias without hitting their dense concentration of leaves. And don’t blame your neighbour if his roses have powdery mildew and your begonias suddenly “catch” it – there are many species of powdery mildew, and the species attacking his roses will not infect your begonias.

A Plant for All Season

Every year, I pick up a few potted begonias for a shady corner of my yard, and every year I think to myself that I’m going to try something different for that spot. But I keep coming back to begonias – they look great and they’re easy to maintain. And isn’t that the very definition of a great plant?

First Published 7/22/2004
Eats Shoots and Leaves

Like thousands of others, I’ve enjoyed Lynn Truss’ witty book on punctuation, Eats, Shoots and Leaves – the “zero tolerance approach to punctuation.” Her obsession with small details that have a huge impact on the bigger picture got me thinking about a comparable situation in my garden.

For the Want of a Comma

The title shows how the presence or absence of a comma can completely change the meaning of a sentence. It’s natural to say that a panda eats shoots and leaves; that’s how we expect pandas to behave. But if a panda eats, shoots and leaves, we might have some legitimate concerns over its table manners.

Truss’ title reminded me of a problem in one of my deck pots. It contains a half dozen lavateras, and a few weeks ago I noticed that some of the leaves were displaying the downward-cupping distortion that is characteristic of aphid damage. Sure enough, once I rolled the leaves back I discovered a virtual army of aphids. However, when I rolled the leaves back, an insect called a big-eyed bug and a tiny spider sensed the disturbance, quickly abandoned the leaf, and disappeared. Both creatures are predators of aphids, and were likely feeding on the pests until I disturbed them. I also noticed a tiny worm-like insect, a syrphid fly larva, yet another aphid predator. Unlike the other two predators, the larva didn’t make a run for it – but then, it had neither wings nor legs to escape.

Seeing these three beneficial insects was enough to convince me I didn’t need to take any special measures to protect my plants; I knew that the aphids wouldn’t be around too long. Sure enough, a couple of days later, all the aphids were eaten and new growth on the lavateras had replaced the damaged leaves. The syrphid fly larva was still there, but without the aphids, the leaf surface must have seemed like an inhospitable desert. Once a predator has consumed all the available prey, things look pretty bleak, and it’s time to move on to greener pastures.

Most gardeners have no idea what a syrphid fly larva looks like, or that it’s a beneficial insect. If you turned over a lavatera leaf and saw this fly, you might be tempted to lay the blame for the damage at its feet. Out would come the spray bottle, and bam – one tried, convicted and executed larva.

Full Stop

Which brings me back to Truss’ book. The syrphid fly doesn’t eat shoots and leaves; rather, it eats, shoots down the aphid population, and leaves once it’s done. Precision is important, whether you’re writing the Great Canadian Novel or simply tending to your plants.

First Published 7/15/2004
The Meaning of Fruit

You might find it somewhat disconcerting to discover that one of the most popular garden fruits, the strawberry, doesn’t actually produce any berries at all. For that matter, neither does the raspberry, nor even the Saskatoon. If you insist on having real berries in your garden, you may just have to turn to one of the most reliable producers of berries: the potato.

Bitter Harvest

Yes, given the proper environment and enough time, potato plants will flower and yield small, green, tomato-like berries. If you don’t believe it, I understand – I once had to drag a couple of close friends of mine out to the potato patch to show them the evidence.

The potato berry isn’t that well-known, mainly because most people dig up the tubers and destroy the potato plant before the berries have a chance to develop, but also because the berries, being rather poisonous, are only useful to potato breeders who collect the seed.

So why should we call this noxious fruit a true berry while denying the designation to more popular berries? It’s because a true berry is defined as a fruit with thin skin, relatively soft flesh at maturity, and typically contains more than one seed. The potato berry fits this definition, as do the fruits of peppers, grapes, eggplants, and tomatoes. (Yes, now you can add “berry” to the “fruit vs. vegetable” tomato debate.) Strawberries, raspberries and Saskatoons don’t fit this definition.

Berry Precise

So if potatoes produce berries, albeit poisonous ones, what exactly are we eating when we pop a Saskatoon or strawberry into our mouths? It all depends on how the juicy morsel was formed.

The word “fruit” is a generic term, used to describe the mature ovary or seed of a plant that is fused to other complimentary parts or structures. For example, an apple fruit – properly called a pome – has seeds surrounded by a mass of fleshy tissue, which entices animals to consume it, seeds and all, and then disperse the seed via the animals’ droppings. A pome is defined as a fleshy fruit with a papery inner structure that encloses the plant’s seed.

Even the winged “seed” of a maple is a type of fruit, called a samara, which is designed to fall from the tree, spin like a helicopter rotor, and sail away on the wind.

True Names

So if a strawberry isn’t really a berry, what is it? Technically, it’s an aggregate fruit, which means that it has hard seeds on an enlarged, fleshy receptacle, and that the fruit was formed by a bunch of pollinated flowers that combined to produce one single, aggregate fruit.

The raspberry is also an aggregate fruit. The Saskatoon, on the other hand, is a pome.

In the end, describing common fruits and berries using strictly correct terms is probably not necessary for the home gardener – in fact, it’s a little pedantic. At best, knowing that a strawberry is an aggregate fruit might win you a few points in a trivia game.

On the other hand, if you’re working on your roses in the fall and you hear passers-by saying, “Wow, those hips are huge!”, you may have preferred they use the proper name – rose pomes – just to avoid any confusion.

First Published July 8, 2004

People grow their own tomatoes for two reasons: the simple pleasure of tending the plants, and the promise of heavy yields of ripe, juicy fruit. To achieve that goal, don’t forget about pruning.

To Prune or Not to Prune
Not all tomatoes should be pruned. Indeterminate tomatoes – essentially, those that grow tall – should be pruned. Determinate, or bush-type tomatoes, should not. But why?

The division between determinate and indeterminate tomatoes is based on differences between their growth habit and vigour. Indeterminate tomatoes don’t know when to quit; if our climate was sunny and warm year-round, these tomatoes would climb up the side of your house and up onto your roof. Determinate tomatoes are just the opposite; they will remain short, bushy and roughly hemispherical regardless of the summer’s length. Or, put another way, in a mild climate, indeterminate tomatoes are actually perennials; determinate tomatoes are annuals.

There’s another important difference between the two groups of tomatoes: they produce shoots differently. Indeterminate tomato varieties begin shoot production by developing leafy branches with clusters of flowers, called trusses, on the stems between the leaf branches. This pattern repeats ad infinitum, provided the weather stays warm and sunny. Determinate tomatoes, on the other hand, begin by producing both leaf branches and flowers, but very quickly the tip of the shoot terminates in nothing but flowers. Since there is no leafy tip to carry on growing, as is the case with indeterminate tomatoes, the leafy growth stops and the leaf energy is dedicated to producing fruit (which are actually correctly called berries – and you thought the fruit vs. vegetable debate was confusing!). In effect, determinate tomatoes are self-pruning.

Indeterminate tomatoes are another story. In greenhouses, indeterminate tomatoes can reach heights of 15 to 20 feet, and if they’re not pruned, they can quickly become overgrown with foliage, at the expense of fruit. By pruning off shoots, you can devote more of the plant’s energy to fruit production.

Fortunately, pruning indeterminate tomatoes is a simple task, as long as you do it on a regular basis. All you have to do is pinch out the tiny shoots that grow between the main stem and horizontal leaf branches. That’s it! Do it weekly and you’ll never need to break out the pruners; your fingers will do the job. Just be sure not to prune out the flower clusters. In the greenhouse, we never prune the top 15 cm or so of the plants’ new growth; this keeps us from inadvertently pruning off new flower clusters or the growing point.

Pruning serves a secondary, but equally important purpose: it shores up the plant’s structural strength. I’ve seen many indeterminate tomatoes split in two because they were not pruned properly; the weight of heavy, unevenly distributed fruit-bearing shoots was simply too much for the plant to bear. A strong wind can easily snap off these heavy branches. Pruning to keep the fruit load distributed roughly evenly all around the plant will help alleviate this problem.

Determining What to Grow
Determinate tomatoes are ideal for gardeners who don’t want to cage or support viny tomatoes, but there is a downside; bush-type tomatoes tend to produce fruit that hangs down and touches the ground, which can lead to rot unless there’s a good clean mulch in place. Indeterminate tomatoes, on the other hand, have the potential to produce much more fruit, but they require staking or caging, as well as the additional work of pruning.

Both determinate and indeterminate tomatoes will provide heavy yields of ripe, juicy fruit; only you can determine which is right for your garden.

First Published 7/1/2004
Rally ‘Round the Willow

It’s Canada Day, and all over the country people are proudly displaying our national symbol, the red maple leaf.

As a gardener, I get a bit of an extra thrill from knowing that Canadians chose a plant – and a fine one, at that – to represent the nation. And while I adore the sugar maple and its leaf that adorns our flag, there is one other leaf, perhaps less inspiring, that belongs to a tree that truly represents some of Canada’s best qualities. That tree is the willow.

The Horticultural Mosaic

Modern Canada is a cultural mosaic, with dozens of indigenous and immigrant cultures creating a nation of rich diversity. Similarly, there are a surprisingly large number of willow species, many of which hybridize, crossing and mixing traits to yield new, unique willows – a horticultural mosaic, if you will. About sixty-two species of willow are native to Canada, with nearly a dozen species attaining tree size, and there are varies species indigenous to every province and territory in Canada, including some of the harshest regions of Nunavut.

Willows range in height from a metre or less for the dwarf arctic species to over 25 metres for the weeping willows. One of the tallest of the Prairie willows is the Laurel Leaf willow, which has glossy green, lance-shaped leaves that hang on to the tree tenaciously, well after virtually every other tree has dropped its leaves in the fall. The Laurel Leaf willow has another unusual feature: a strange growth habit. On older trees, the Laurel Leaf’s bark spirals up the tree, making the trunk look like a twisted piece of licorice. I’ve never found a definitive reason for this spiraling bark, although there are theories that give the credit to prevailing wind patterns. (I’m not completely convinced.)

Some species of willow look nothing like their stereotypical image. The variety ‘Polar Bear’ (Salix silicola) has very soft, furry, silvery-blue to white leaves, and its branches grow in a very contorted fashion. Few people would ever recognize this variety as a willow species, but it certainly makes a great conversation piece.

Health Care Hero

In Canada, we place great value on our health care system, and as it turns out, willows have their own role to play in human health. A chemical called salicylic acid is found in substantial quantities in willow bark. Historically, the bark was chewed by indigenous North Americans to relieve pain; eventually, the modern world caught on to the medicinal value of willow and created a synthetic version of the acid, called acetylsalicylic acid, better known as ASA, the active ingredient in aspirin. (The genus name for willow is Salix, for the acid, and the “spirin” in “aspirin” alludes to the fact that salicylic acid was also extracted from a common garden ornamental, the spirea.)

It Is…Canadian

In many ways, the willow is the perfect Canadian plant: tough enough to withstand the harshest Canadian winters, and tolerant enough that species will freely cross, resulting in a wide variety of attractive forms.

Tough, tolerant, and diverse – how quintessentially Canadian.