First published June 21, 2007

The dictionary defines pruning as “The removal of dead or living parts from a plant.” I think the definition should be expanded to include “A task often avoided by gardeners because of the anxiety its mere contemplation causes.”

I’m not sure why so many people are mortified by the idea of pruning trees or shrubs, but I would hazard that it’s linked to a healthy fear of killing or horribly mutilating one’s favourite plant. The key to conquering this fear?—I’d say a deep breath and a good understanding of the process is a great place to start.

Baby steps
Pruning can involve anything from a simple snip of a rose shoot to the Cirque de Soleil-like aerobatics of certified arborists. The main principle, however, is relatively simple: remove some of a tree or shrub’s tissue as a means of guiding its architecture. Unfortunately (but not surprisingly), most of us aren’t so great at guiding architecture. Instead, we tend to ignore it until it gets really bad—bad to the point where we feel there’s nothing to lose; bad to the point where we overcome our fear, grab the pruners and start indiscriminately cutting. So what’s the solution?

I always start with two recommendations: begin pruning early in the life of your trees and shrubs, and always remember to remove the least amount of growth possible. When you prune lightly and regularly, you remove a relatively small amount of energy (carbohydrates and other compounds stored in leaves and branches) from the plant. Removing a large proportion of a tree or shrub’s growth will cause a serious strain on its resources and can take the plant years to recover from (if you’re lucky). That’s why the rule is never to remove more than about 20 per cent of a tree or shrub’s live growth in a single season. Of course, an exception can be made when a tree has been damaged in a storm or by disease—then removal of more than 20 per cent of the plant’s growth may be a necessary evil.

Timing is everything
Timing is another aspect of pruning that causes much consternation. When is the right time to prune? Well, it depends. When it comes to broken, diseased, dying or dead branches, it’s always open season. And if a low hanging branch beans you in the head every time you mow the grass, then, by all means, remove it, too. Just remember that there is only one way to make a proper pruning cut on a tree, and that’s done by leaving a 1-cm “collar” on the trunk where the branch was. No long stubs. No cuts flush to the trunk.

As for figuring out when to prune spring-flowering shrubs and when to prune summer-flowering shrubs, there’s a fairly easy rule to remember: if you want maximum flower production, prune spring-blooming shrubs in early summer, and prune summer-blooming shrubs in early spring. For example, lilacs and flowering plums bloom in spring (prior to June 20th) and should be pruned shortly after they finish blooming so that next year’s flowerbuds have time to form during the summer. Shrub roses, on the other hand, should be pruned in early spring because the flowers are formed on the shoots that develop during the spring. I would have to say though that the best thing about this rule is that even if you get mixed up and prune the wrong plant at the wrong time, you won’t ruin its health—you’ll just be forced to enjoy its foliage rather than its flowers.

That really is all there is to understand about the basics of pruning…well, that and one more thing: in an attempt to control disease and pest problems, various regions across the country have banned pruning during certain times of the year. On the Prairies, American elms are not to be pruned from April until October because of the threat of Dutch elm disease. In fact, it’s actually illegal to prune Americans elms during the restricted time. Hmmm, going to jail for pruning an elm…maybe that fear of pruning is warranted after all.

Enjoy Gardening!

Powdery mildew is Jim’s least favorite plant problem and he gives you some background information on how to deal with it.
Quicktime
WMV

Hits & Misses: The good child & stephanotis soup
Question of the Week: Why are my white peonies blooming pale pink this year?
The Business: In the hot or the cold seat

According to Flower Tech magazine, officials are planning on beautifying the city of Beijing for the upcoming Olympic games by creating a “floral belt.” Apparently, some thirty million pots of flowers will adorn the streets and Olympic venues during the games. Hmmm…if it took one person 10 seconds to water a pot, that one individual would have to work non-stop for over nine years to water every pot just once! And that’s without any time allotted for resting. No thank you.

Hits & Misses
Hit: The Good Child
It looks like the ‘Endless Summer’ hydrangea in our show garden is going to be full of blooms this summer. For the past several years, it has produced a wonderful display of foliage but has failed to generate a single flower. Naturally, I threatened to pull the plant out this year if it had one more flowerless summer, and the nearest that I can figure is that it heard me. It’s good to know at least someone’s listening.

Hydrangeas are among the showiest summer-flowering shrubs and have huge flowerheads that last for up to three months.

Miss: Stephanotis Soup
We had a couple of stephanotis plants arrive this past week with a few mealy bugs on them. Normally, when we find bugs in our shipments, we just send them back to the supplier, but this time I decided to experiment with a hot water treatment I read about in one of my horticultural research publications. What we did was dip the entire plants into 49 C water for two minutes to see if it would kill the mealy bugs without harming the stephanotis. The results were bittersweet: the mealy bugs were destroyed, but so were the plants. Of course, in all fairness to the research article that inspired this experiment, there was never any mention of trials on stephanotis. I’m almost positive that means I have only myself to blame for the pot of stephanotis soup that I seem to have made.

Question of the Week
Why are my white peonies blooming pale pink this year?
Plant pigments are responsible for flower colours and can be affected by factors such as day and night temperatures, soil pH and moisture. In the case of your peonies, what’s likely happened is that the recent spate of cool, cloudy and showery weather has shifted the pigmentation toward the pink spectrum. Unfortunately, there really isn’t anything you can do to “correct” it other than hope for better weather this time text year—sun and warmth favours bright, white flowers.

Never add manure to the soil when preparing a planting hole for a peony; it will result in weak, spindly growth.

The Business
In the hot or the cold seat
Garden ornamentation is nothing new, but it does seem to be enjoying a surge of popularity. The result of this interest is some truly unique pieces. One that caught my eye was a beautiful set of lawn furniture that was made entirely from large boulders that were carved to fit the human form. They looked really impressive, but I couldn’t help wonder about the comfort level of this furniture given rock’s propensity for either being frying hot or stone cold.

Did You Know?
The voodoo lily (Sauromatum guttatum) can increase its temperature by 14C to volatilize pungent floral odours that will attract insect pollinators.

“In gardens, beauty is a by-product. The main business is sex and death.”
–Sam Llewelyn

3 cups tricolour fusili pasta
4 Roma tomatoes
1/4 cup olive oil
24 to 30 baby zucchini, sliced lengthwise
10 large basil leaves, chopped
1 1/2 cups heavy cream
salt and black pepper to taste
2 tbsp. flat-leaf parsley, chopped
1/3 cup grated Parmesan cheese

Cook the pasta according to package directions. Set aside but keep warm. Blanch the tomatoes by plunging them in boiling water for 1 minute, then cooling in cold water. Remove the peel and seeds, then chop coarsely. Heat the oil in a large saucepan over medium-high heat. The oil must be hot. Add the sliced zucchini and cook until the zucchini begins to turn golden-brown. Add the garlic, tomatoes, and basil leaves; pour the cream over the ingredients. Makes 4-6 servings
Shake the pan to mix the ingredients; season with salt and pepper. Cook for 1-2 minutes. Spoon sauce over the tricolour pasta, sprinkle with parsley and Parmesan cheese, and serve hot.

Recipes courtesy of Zucchini: You never have enough

first published June 14, 2007

The Day of the Triffids by John Wyndham was my favorite “plant” book back in high school. Like most teenage boys, I was quick to agree that looking at petunias couldn’t hold a candle to reading about alien plants capable of uprooting themselves and chasing down humans for lunch.

Good plant, Bad plant
I’ve always thought The Day of the Triffids was a great work of science fiction, but I like to imagine that Wyndham’s inspiration for writing about earth-invading alien plants might have been based on the battles gardeners wage against their own triffid-like plants—real-life aggressors that include plants like mint (Mentha), goutweed (Aegopodium podagraria), lily of the valley (Convallaria majalis), Himalayan impatiens (Impatiens glandulifera), horseradish (Armoracia rusticana, syn. Cochlearia armoracia) and bellflower (Campanula latifolia var. macrantha). Anyone who’s planted one of these pillagers in the wrong spot probably wouldn’t need much convincing to believe that certain plants are capable of sprouting legs.

The thing about some of our more aggressive spreading perennials is that we expect them to have split personalities. We want them to be tough invaders when we plant them in the most inhospitable spots in our yards, and then we want them to abruptly stop spreading when they hit the periphery of the area we allocated for them. Naturally, we become frustrated as we watch them march on relentlessly against our wishes, transforming from pretty ornamentals to vulgar weeds. So how do we deal with good plants that go bad? Well, a good place to start is by understanding two important things, the first being each plant’s modus operandi—how it becomes invasive.

Understanding how to deal with an invasive plant means understanding that plant’s habits. Himalayan impatiens, for example, spread entirely by seed, so preventing them from setting seed (by cutting them back after they bloom) will keep them from becoming the equivalent of bad houseguests who won’t leave after long after they’ve worn out their welcome. Raspberries have their own sneaky habit of shooting up sprouts from dormant rootbuds, particularly after canes are severely pruned. Others, like bellflowers, grow upright until their creeping stolons hit your lawn, then surreptitiously begin to creep through the grass blades, forming turf-penetrating roots at each leaf node.

The second thing to remember about aggressive plants is never to tempt them. Just as the most resolute dieter will succumb to rich, moist chocolate cake, so too will plants like goutweed be unable to resist a bare patch of rich, moist soil in close proximity to where it was transplanted. Physical barriers like sidewalks and deep edging will effectively imprison invasive spreaders, but attempting to halt their spread by hacking them back just seems to make them more angry and determined. The fact is, the only additional ingredient needed to transform an aggressive ornamental into a weed is opportunity.

Goutweed (Aegopodium podagraria) is great plant for spots where nothing seems to grow, as long as you keep it contained.

Solitary confinement
So what can we do to enjoy these plants long term? Well, one solution is to grow them in their own little prisons…er…I mean, containers. A colleague of mine has had great success planting oversized pots of goutweed and countersinking them in her flowerbeds. This method gives her the look she wants without the worry. If you want to give this method a try, know that you’ll have to be fairly faithful about watering—because there’s a barrier between the perennial’s roots and the groundwater, it’s easy for the soil in the container to dry out. Oh!—just one word to the wise: some plants simply refuse to have their enthusiasm contained. When my colleague tried containing her avaricious mint plants in buried pots, the mint roots grew out the drainage holes and found their way into her garden soil. Hmmm…perhaps mint is just another name for triffid.

Hits & Misses: Delphiniums & stray spray
Question of the Week: What are the black, nut-like clusters on my mayday?
Science & Technology: Ladybug! Ladybug! Fly away home

There are many plants and decorative accents that can be added to patio containers to make them both beautiful and unique. And I have recently acquired one “decorative accent” that I’m pretty sure is quite unusual. It’s not a plant or a bobble, but rather a bird of prey called the Northern Goshawk. It has a nest somewhere in the neighbourhood and has taken a liking to perching on the brim of one my large flowerpots and scanning the area for potential prey. Ever since I was a kid, I loved studying birds of prey, so watching this wonderful bird up-close has been a rare treat. On the flipside, the local squirrel population seems to have taken a bit of a dive as late…a fair trade, in my opinion.

Hits & Misses
Hit: Delphiniums
The ‘Early Blue” Guardian delphiniums that we transplanted three to a pot are just starting to bloom in the most beautiful shade of iridescent blue. The tall flower spikes on delphiniums always make a bold, dramatic statement at the back of borders and are great for bringing indoors as cutflowers. Best of all, this variety doesn’t require staking and will bloom the first season without fertilization!

Delphiniums prefer rich soil, so work your flowerbed deeply before planting, and add lots of compost, well-rotted manure or peat moss.

Miss: Stray Spray
I’m starting to see a lot of misses brought in by customers when it comes to tomatoes—misses, that is, in the sense of missing one’s weeds with the herbicide and hitting the tomatoes instead. Tomatoes are particularly sensitive to 2,4-D, which is one of the main ingredients in lawn weed killers. So if you don’t have a particularly steady hand and you’re not big on the idea of replanting, give the tomato patch a wide berth when spraying.

Question of the Week
What are the black, nut-like clusters on my mayday?
Your tree has likely been stricken with a serious plant disease called black knot of cherry. When the trees are at the fruiting stage, the disease seems to billow out of branches. The only solution is to prune out the affected branches well below the knot. Just be sure to seal the pruned branches in a plastic garbage bag and to clean your pruning tools between cuts with a bleach solution to prevent spreading this disease. This is an especially important step because black knot affects all members of the genus Prunus—cherry, mayday, plum, etc. I recommend a cleaning solution containing one-part bleach to nine-parts water. Bleach is corrosive to tools, so never let them sit in the solution for any length of time.

The fallen berries from maydays can be messy, so avoid planting them near patios and driveways.

Science & Technology
Ladybug! Ladybug! Fly away home
Ladybugs are great for eating the aphids in our yards, but they have a tendency to fly away to look for greener pastures of tastier aphids. This, however, may be about to change. Entomologist are attempting to breed wingless ladybugs. The idea is that the wingless ladybugs will linger longer on your plants and do a better job of cleaning up your garden’s aphid population. I don’t doubt that the ladybugs will be happy to sit around and feast all day, but I’m guessing they won’t be so happy about being wingless when predators pay them a visit. Perhaps that old nursery rhyme will have to change to “Ladybug! Ladybug! Walk away really quickly.”

Did You Know?
You can rent bees! Some farmers rent bees colonies to increase pollination and fruit yields.

“Plant on a whim. Lay the footpath where your heart says it should be.
Change things because you feel like it. Garden for the love of it.”
–Lindley Karstens

2 cloves garlic, minced
5ml oil
1 small onion, sliced
3 sliced green tomatoes
1 ripe tomato, cut into wedges
5ml basil
1ml salt
0.5ml pepper
0.5ml sugar

Place wok directly on lava rock in gas barbeque. Over medium heat, sauté garlic in oil for one minute. Add onion and green tomatoes and stir-fry until vegetables are tender, about 5 minutes. Add ripe tomato and seasonings; heat through, about 2 minutes. Serves 4.
Note: halved cherry tomatoes may be substituted for the ripe tomato.

Recipe Courtesy of: Blue Flame Kitchen
and Lois Hole’s Tomato Favorites

first published June 7, 2007

The one thing I really miss about childhood is the simplicity. To my juvenile way of thinking, all flowers were just pretty blossoms visited by nectar-loving bees that spread pollen from one flower to another in order to produce seeds. The pollination story was simple and elegant and, unfortunately, too perfect to be true.

When we see apples, plums and pear trees in full, glorious bloom, we can’t help but envision our kitchen counters lined with bowls of homegrown fruit. But before that can happen, we must first win the pollination battle—a battle against bad weather, bugs, drought and hungry animals. Even when those enemies are defeated, there’s still the issue of the right type of pollen finding its way to the right flower parts. Without this critical step, even the most robust of plants will fail to yield a single fruit.

The topic of pollination can be daunting, so it helps to break fruit-bearing plants into three categories: varieties that self-pollinate, varieties that require cross-pollination, and—just to keep things confusing—varieties that don’t require pollination but that will fruit better with it.

Tomatoes are almost entirely self-pollinated, requiring little more than a bit of wind or the occasional visit by a bee to produce a nice crop. Even in our windless greenhouses, the task of helping the pollination process along wasn’t complicated. We’d just vibrate the tomato flower stems (trusses) with something that resembled an electric toothbrush to ensure that we’d have a high percentage of fruit set—quite a simple affair.

Sour cherries (‘Evans’ and ‘Carmine Jewel’ are two popular varieties) are another group of self-pollinating plants that do just fine on their own, but other common fruiting plants, like apples, need viable pollen delivered directly to their doorsteps by a process called cross-pollination. For example, an apple like ‘Goodland’ needs pollen from an apple variety like ‘Norkent’ before fruit will develop. Both are considered pollinizers, a.k.a. plants capable of providing good quality pollen that leads to viable seed production. Typically, it’s various species of bees (pollinators) that unintentionally take on the arduous task of moving the sticky pollen from plant to plant.

Now if you want to step it up a notch in the wonderful world of pollination biology, you need look no further than the plum family. Plums and cherries (not the sour cherries) are supposed to require cross-pollination to produce fruit. That’s what I learned, and that’s what the books say, but I’ve had people swear up and down that some members of the plum family (‘Nanking’ cherries, in particular) are completely self-pollinating. Adding to the controversy, research out of the University of Saskatchewan shows that most of the plum varieties touted as being suitable pollinizers have rather sterile pollen and that it’s only wild plums that possess pollen with the necessary vigor to pollinate. So, shy of getting a Ph.D. in pollination biology, what’s a gardener to do?

Well, until more rigorous scientific research is available, my recommendation is simple: take the shotgun approach. Do everything you can to encourage visits by bees and other pollinating insects, regardless of whether or not your fruiting plants are self- or cross-pollinators—it can do nothing but increase your odds of producing more fruit. Plant different varieties of related fruiting plants and glance over your fence to see if there are compatible plants in your neighbours’ yards. If neither of these are options, seek out friends or family who will give you a few branch cuttings of compatible plants that are in bloom, place the branches in water-filled jars and hang them from the trees you want pollinated. Bees will fly from the flowers in the jar to the flowers on your tree, increasing the odds of successful pollination.

Pollen really is fascinating stuff. It’s not a good mate for some flowers, a perfect mate for others and, on occasion, needs to be shaken up a bit to do its job. Hmmm…sounds like members of another species I know.

Jim shows you a few things you need to do to keep your containers looking good throughout the season.
Quicktime
WMV

Hits & Misses: Potunias & Mother Nature
Question of the Week: Why isn’t my lilac blooming?
Science & Technology: Chondrostereum purpureum

A lot of people are feeling a bit creeped out lately thanks to an invasion of hungry caterpillars called inchworms or loopers. These worms have voracious appetites and can leave a tree looking tattered, at best, or virtually denuded, at worst. They also have the rather unpleasant habit of dangling from silk threads, landing on our clothes and hitching rides into our homes. Well, the good news is we won’t have to worry about caterpillars accessorizing our outfits or chewing on our trees for much longer—soon they will focus on dropping to the soil to pupate before re-emerging as moths in the late summer or fall. However, if that doesn’t bring you any peace of mind or you need to take steps to keep this pest under control, look for a product that contains a bacterium called Bacillus thuringiensis. It’s effective and, most importantly, will not harm beneficial predatory insects.

One final word of advice to the squeamish: avoid renting the sci-fi movie Invasion of the Body Snatchers—a story about cankerworms that encase sleeping humans in cocoons probably won’t amuse you at this time of the year.

Hits & Misses
Hit: Potunias
Hats off to the plant breeders at Dummen! They’ve bred a variety of petunias specifically for containers and pots, and I’m quite impressed with them. They are called potunias (huge surprise!) and produce a mass of both purple and pink flowers on compact plants. We’re currently potting up a bunch of them for the Grand Prix car race in Edmonton and are really happy with how they look. High-performance vehicles meet high-performance plants!—sounds like a perfect fit.

Miss: Mother Nature
The downpour that accompanied the near tornado-like weather in the St. Albert area last week was the heaviest I have ever experienced at the greenhouse. Our gutters, which rarely fail us, were unable to handle the torrential rain, and water gushed out of every spot where it could find the slightest opening. Luckily, other than the odd washed-out flat of pansies and a few hail marks on some delphiniums and petunias, damage was minimal.

Question of the Week
Why isn’t my lilac blooming?
A few culprits could be at work here, the first two being the age and location of your lilac: lilacs that are very young or growing in a spot with too little sun (lilacs need a minimum of six hours of direct sunlight each day to set flowerbuds) won’t bloom. Then again, it could just be that it’s all your fault…that is, you may have inadvertently cut off this year’s flowerbuds last year. Lilac flowers should be pruned only after the flowers fade and turn brown and should never be cut back too severely; otherwise you risk removing the buds for the next season’s blooms. Over-fertilizing with nitrogen can also prevent lilacs from blooming…which would likely be your fault, too. Live and learn!

It takes most lilacs up to six years to reach their peak blooming potential.

Science & Technology
Chondrostereum purpureum
The Pest Management Regulatory Agency here in Canada recently approved the use of Chondrostereum purpureum PFC 2139. You’re probably thinking that’s great!—now what the heck is it? Well, first some backstory. C. purpureum is a fungus that causes a disease called silver leaf. It attacks a variety of weakened trees and shrubs, leaving a leaden sheen on their leaves, thus the name silver leaf. In the forestry industry, elimination of trees that send up suckers after being cut down is an important management tool. This is where C. purpureum fits in. Because C. purpureum is naturally occurring and safe for an expert to use, it can be spread on the stumps of certain tree species to cause them to die and decay fairly rapidly. It doesn’t invade healthy plants so it doesn’t pose any great risk to desirable plants. A win-win situation.

Did You Know?
In the language of flowers, lemon balm symbolizes sympathy.

Quote
“Plants are like people: they’re all different and a little bit strange.”
–John Kehoe