Space Invaders

Over 800 alien plant species have invaded Canada, more than 400 in Ontario alone. Most recently, kudzu vine, bane of the southeastern United States, has made its way northwards and in 2009 slipped across the border near Leamington.  Fortunately, it was soon spotted and is being closely monitored. Other pesky invaders are already well established here in meadows and woodlands, beside trails and waterways, and quite possibly in your own backyard.

According to Stephen Murphy, Professor and Chair of the Department of Environment and Resource Studies, University of Waterloo, garlic mustard is number one on his list of most troublesome plants in this region. Challenging garlic mustard for top place is common buckthorn followed by dog strangling vine, Japanese knotweed, and dame’s rocket (Hesperis matronalis). Dame’s rocket is often referred to as wild phlox — yes, that plant with the lovely purple and mauve flowers. Yet it’s a serious menace, posturing as a native flower in a beautification project while quietly intruding into woodlots, overwhelming early spring ephemerals.

Garlic mustard (Alliaria petiolata), meanwhile, may sound like a perfect condiment, and has been called poor man’s mustard, but it’s a prolific self seeder, and is unthreatened by the insects and fungi that keep it under control in its native habitat — Europe, Asia, and parts of Africa. Deer rarely eat it but can aid its spread by disturbing the soil, creating optimum conditions for further regeneration. Garlic mustard also has a negative allelopathic effect by producing chemicals that suppress soil organisms required for optimum growth of native plants like blue cohosh, trout lily, and bloodroot. Even our beloved trillium faces eviction. “Garlic mustard overwhelms these smaller understorey plants,” says Professor Murphy, “while buckthorn moves in on the overstorey plants.”

Common buckthorn (Rhamnus cathartica) can grow to a height of two to three meters or more. It produces berry-like fruit that is eaten by animals and birds, particularly starlings. In return, these helpful critters carry out a handy seeding program by making deposits far from the source, resulting in new colonies. Like many invasive plants, it was originally introduced as an ornamental plant, often used as a hedge or windbreak. It’s one of the first plants to leaf out in spring, forming a dense canopy leaving seedlings of native plants and trees in the dark.

Almost as troublesome is the ominous sounding dog strangling vine (Cynanchum rossicum). If you’re regularly kept awake by a hound from hell, a dog strangling weed may not sound like a bad idea to you. It’s an herbaceous perennial twining vine that forms a loose, ropy canopy, choking out competing vegetation. I’m not aware of dogs actually meeting their demise due to this plant, but I might be concerned if Rover vanished into a patch with a magazine or Sudoku puzzle. DSV has become the number one problem for Joshua Shea, Natural Area Coordinator with the City of Kitchener. “It’s widespread, particularly in the Huron Natural Area,” he says.

A member of the milkweed family, DSV doesn’t have any natural enemies as it does in its native Europe, but monarch butterflies are attracted to it. This concerns environmentalist Sean James, a graduate of the Niagara Parks School of Horticulture and expert on invasive plants. “The monarchs lay their eggs on the plant, but the plant doesn’t support the development of the larvae. Regrettably, this has an impact on the number of butterflies.”

Even if the DSV is physically removed, it readily re-roots (picture the scene in "The Sorcerer's Apprentice" where the broomstick chopped up by Mickey Mouse becomes an army of brooms). Nothing appears to have a permanently damaging effect on this plant as it even tolerates burning and resists herbicides.

Perhaps the most aggressive invasive plant is the dreaded Japanese knotweed (Fallopia japonica). It, too, was introduced as an ornamental plant back in the nineteenth century, and has since made tremendous headway in its quest to take over the world. If it appears in your garden, moving may be the only option as it is notoriously difficult to eradicate. By the time it’s stuck its head above ground — even through asphalt or concrete, vigorous roots are already spreading laterally as far as ten meters and up to three meters deep — try digging that up! Leave behind the tiniest fragment and it will sprout a new plant, while parts of the stem will produce shoots and roots within days when dropped into soil or even floated in water.

The above plants cause the greatest problems, but there are many garden plants that given the opportunity will make a break for freedom. They may appear innocuous; I mean, who could be concerned about the delightfully fragrant lily of the valley, periwinkle with its cute blue flowers, or goutweed, the oh so efficient ground cover. They may be acceptable, even useful — if restrained by concrete, but given the chance they’ll take over flowerbeds or whole gardens and potentially create rifts in an otherwise peaceful neighborhood.

These sneaky plants recognize no boundary and will quickly overrun or crowd out native plants. “It’s important for the municipality to monitor for early detection,” says Josh Shea, “particularly the border between private gardens and parks or wilderness areas.”

Although there are limits on the use of herbicides, particularly in private gardens, digging and removing as much as possible of the plant then stifling it with a black plastic cover for as long as a year or more can be effective.

While there may not be easy solutions to deal with invasive plants, there has been success with Purple loosestrife, the plant once feared would colonize every wetland in the province. It has been brought under reasonable control thanks to the release in the late 1980s of a pair of leaf eating beetles, but only after extensive research was done to ensure the helpful bugs would not move on to native plants.

This may be viable solution for other problem plants, and research is underway but it takes years of study and sufficient funding to ensure there would be no unexpected consequences. “Unfortunately,” says Professor Murphy “although the Canadian Food Inspection Agency, for instance, has some control at airports, there is no one stop organization for control of invasive weeds. Municipalities, however, do a reasonable job with the funding they have.”

Although there is no monitoring of invasive species at the regional level, most local municipalities usually have a weed inspector on staff. Some municipalities enlist volunteers to help track and monitor invasive species in natural areas or assist in labour intensive eradication programs. While vigilante groups can also be helpful, it is important that they be aware of property issues and have an expert on hand to aid in identification.

Meanwhile, homeowners need to be vigilant and persistent if they are to eliminate invasive plants from the garden, or avoid inadvertently introducing invasive plants. The Ontario Invasive Plants Council offers a useful “Grow Me Instead” guide at http://www.ontarioinvasiveplants.ca/ while Ontario’s Invading Species Awareness Program recommends the following strategies:

Learn how to properly identify Japanese Knotweed and how to effectively manage invasive plants on your property.

Avoid using invasive plants in gardens and landscaping.

Purchase non-invasive plants from reputable suppliers. When gardening, consider the use of native plants which provide habitat and food sources for wildlife.

Do not dispose of invasive plants in the compost pile – discard them in the regular garbage or check with your municipality for disposal information.

When hiking, prevent the spread of invasive plants and seeds by staying on trails and keeping pets on a leash.

But why care, you may ask, as long as natural areas look more or less greenish? Unfortunately, when the biodiversity of ecosystems is disrupted or destroyed by invasive species, there are long term effects and often unexpected consequences. Besides removing a food source for birds and animals, alien plants harbour pests and disease that threaten agricultural crops. Ontario Ministry of Resources estimates that every year, invasive plants cost the agriculture and forest industries in Canada about $7.3 billion.

And besides, this is our home and native plant land . . . so please stand on guard.

Winter Seed Sowing

I’m going to sow seeds outdoors, this week — really. If you’re imagining me pushing a snow shovel across the veggie garden to get to the soil, forget it. I won’t be in the garden as most of the process takes place indoors.

I’ll be winter sowing, and compared to growing seedlings indoors or under lights, it’s less finicky and costs almost nothing. Winter sowing produces tough, sturdy plants, unlike the weak-kneed specimens grown on a windowsill. You can start tomorrow or anytime over the next couple of months.

Most annuals and familiar perennials, and cool season vegetables can be winter sown, but you won’t have any luck with tender plants or exotic species. A good choice are plants that are referred to as hardy, or come with instructions to direct sow outside in fall or in early spring. These are plants that would normally cast their seed in fall, and then sprout up the moment conditions are right. Sure, in the garden many may be considered weeds, however in my garden they’re more likely to be popular garden plants that I grew the previous year. I look on these as free plants — or grandchildren.

When we grow plants indoors, some seeds come with instructions for special treatment that simulates what they typically experience in their normal outdoor environment. They have to be soaked for a time or scarified, that is, nicking or using sandpaper to wear down the hard husk. Others have to be given a spell in the freezer for the purpose of cold stratification. This freezing and thawing or cool dampness outdoors is what breaks down the tough husk of the seed, allowing it to germinate. To reproduce the same process indoors can be tedious and not always reliable.  Winter sowing takes care of this naturally.

You’ll be pleased to hear there’s no need to go tramping through the snow, but simply plant seeds in jugs and set them on the deck or patio. All you need are a few clear or opaque containers and soil and seeds. Gallon jugs are perfect, and all those windshield washer jugs are fine, just rinse well. Some use two litre water bottles. I really like the large water dispenser bottles.

First, drill or cut a few small holes in the bottom of the container. This is to allow excess water to drain but not so large that the soil could fall out. If the container has only a very narrow opening, make a couple of extra holes or cuts near the top to allow for air circulation. Next step is to slice open the container about two thirds up on three sides, leaving one side (or a small section if the container is round) to act as a hinge.

Now place soil in the container. Garden soil is fine, but you don’t want to be out digging in the garden at the moment. Most any potting soil will do. Moisten the soil then sow your seed. Cover them as per packet instructions, or if unsure, about the same as the diameter of the seed. Close up the container and tape it shut along the sides but leave the screw cap off. Now all you have to do is set them outdoors.

If snow buries them, don’t worry. A little snow will fall in and that’s okay too, however, check occasionally to be sure the soil hasn’t dried out. If the weather is especially warm in early spring, remove the tape and open the containers for a while during the day. As the seeds sprout in early spring, you can open them up and leave them open. When the seedlings are large enough they can be planted in the garden.

There, you’re almost gardening already. What a great start to the new year.

Poinsettia Panic

One hundred and seventy three already. That’s how many poinsettias I’ve encountered so far this Christmas season. I have my rules — these have to be live poinsettias and not in a store or greenhouse, unless the store is displaying the plant as part of a seasonal display.Here’s what I say: First remove the foil from around the pot or poke holes in the bottom otherwise excess water will rot the roots. Locate in a sunny window, but not against the glass. Maintain at a daytime temperature of 18 to 21C and if possible, move to a cooler place at night, but no cooler than 15C to avoid root rot. Avoid exposure to hot or cold drafts as these can cause premature leaf drop. Water well when the surface is dry to the touch. Finally, poinsettia is not poisonous, but I wouldn’t eat it. 175, 176,177 . . .


This all started because of my aversion to poinsettias; it was getting worse each year. Don’t believe me? — read previous columns where I’ve complained about the boring ubiquity of these plants, the sheer numbers, the environmental impact of all that wasted potting soil, the energy required to grow and transport them, and don’t even mention the plastic pots that end up at the dump. Grocery stores charging five cents for a plastic bag? I think they missed a huge opportunity here. I say supply your own pot.

Trouble was, I was beginning to be perceived as a Christmas Scrooge, a real grouch bent on spoiling the pleasure of others. I tried not to, but whereas I used to only frown and grumble, I was beginning to openly sneer at these — ahem — plants. Oops, there I go again. I’m sorry. I am trying. Hey, at least I call it the Christmas season and not “holiday” season.

Anyway, the answer was counselling sessions, where I came to realize that unless I was to become completely ostracized by society I would have to learn to like poinsettias. Clearly they’re not going to go away. It was suggested I turn it into a game or challenge and it’s helped considerably. I can now smile when I see a poinsettia, knowing that I’m further along on my quest to set a personal record.

It’s such fun, and it makes Christmas shopping much more pleasurable. I now enter stores full of hope that there’ll be a poinsettia on display — there always is. Naturally, my face lights up immediately, which has the effect of cheering up the frazzled sales assistant, thereby resulting in especially good service.

When I attend a Christmas function, I no longer get annoyed when a whacking great green and red object has been plonked in the middle of the table, completely obscuring my dinner partner, causing us to bob and weave like a couple of boxers as we try to have a conversation. Now I can hardly contain my enthusiasm. I even leave my table and explore the room, anxious to ensure I count them all.

I appear to be the most gregarious, happy person present as I visit other tables, smiling and chatting, saying things like lovely, great, or terrific, even though under my breath, I’m counting away. My obvious enthusiasm then gets me into numerous conversations about how to care for poinsettias.

No bedtime stories in this garden

It’s that time of year again when I keep hearing about bedtime for the garden. That is, putting the garden to bed.

It’s an old term from when that was the idea, that gardens should be put to bed for the winter. My gardens are already in bed, they never left it. What’s a flowerbed if not a bed for plants. Same with a bed in the vegetable garden, or a raised bed.

What the term meant was ripping out all the summer annuals, hacking down perennials and ornamental grasses, and the one thing that does symbolize bedtime, is wrapping evergreen shrubs in burlap blankets. Most of this is unnecessary. Rather than consider this time of year as the end of the season, a time to put things to bed, I prefer to think of it as an extra early spring because so much of what we do now has an impact on next year’s garden.

Certainly, we should take care of anything that would be damaged over winter. Bring all tropical plants and any houseplants indoors before they’re damaged by frost. Better still, do it a couple of weeks ago to avoid shocking them. Dig up and store any tender bulbs like begonias, calla and canna lilies, and dahlias. Turn off all outside faucets, empty rain barrels, and drain hoses. Any planters that could crack if frozen should be emptied and stored dry.

But as for the sleepy garden, there’s no reason to do anything much, and no reason to hack down plants. Perennials are much better left standing just as they do in nature. For instance, all those wild asters that are blooming now will return next year as though nothing happened. Tall plants collect snow which gives protection, the seed heads feed birds, and the hollow stems provide refuge to beneficial insects, plus, the old flowers can be surprisingly beautiful when topped with snow. Come spring these plants can be chopped, dropped, and left where they fall. The old stalks will slowly decompose, returning nutrients to the soil while new growth soon hides the remains. As for annuals, they don’t need wrenching out. Save yourself all that work. Squish them down in spring, and like the remains of perennials, they’ll eventually vanish into the soil.

Then there are all those leaves to deal with. You could make a huge pile as I do, rotting them down to use as mulch next summer. If they’re on the lawn, providing they’re not extra deep, run the lawn mower over them. Once shredded, they’ll break down fast and be gone by the time you’re ready to cut the grass in May. Leaves are simply free fertilizer and a valuable resource, crammed with nutrients that recycle naturally. No one rakes leaves in the bush, but plants still appear in spring. If they fall on flowerbeds, so much the better. We often say keep the crowns of perennials clear, but providing the layer of leaves isn’t dense, the plants usually manage to thrust their way through as they would in the wild. But should you bury them knee deep in packed leaves they will have a problem sprouting in spring.

One place you can pile the leaves is around and under shrubs, especially those that aren’t the hardiest. Butterfly bushes for instance, usually die back to the ground, but in a hard winter they don’t always recover. They’ll love any extra protection.

Shrubs that are hardy don’t need any help so there’s little point in wrapping them. If you’re challenging the zone with tender ones, then do wrap these in burlap, but tough old conifers shouldn’t need anything unless they’re subjected to salt spray.

Finally, it’s a good idea to clean and rub down garden tools with oil before winter, though I often feel it’s me that could use an oiling and a rub down after hard work in October, which is why my garden only gets a bedtime story.