Category Archives: Websites

Some Fascinating Off-Season Reading

By Laura Gardner, Master Gardener

Now that the gardening season has winded down, I’ve turned my attention to some interesting reading. On my nightstand there are some little books that I’ll pick up and read a few snippets just before bed. They are part of a series called “Pedia” published by Princeton University Press.[i] The word “pedia” comes from the Greek word “paideia” for “learning” or “education.” There may be a perception that University presses publish only heavy academic titles. However, many do publish titles that are suited for the general reader. In this particular series, so far it covers the subjects flora, insects, trees, fungi, geology, dinosaurs, birds, and neurology. The petite clothbound books are like miniature encyclopedias, each with around 100 entries on a wide range of topics. Some of the entries are so fascinating that I needed to find out more.

Here are three entries that show gardeners the symbiotic relationship between insect species such as bumblebees, beetles, ants and selected plants:

In “Florapedia,” there is an entry for the plant Cornus canadensis (Bunchberry), a native of the Dogwood family that can be found in some of our Peterborough County forests. Its flowers are said to be capable of the fastest movement in the plant world. As a self-incompatible plant (i.e., unable to self-pollinate), it relies on a unique process of pollen transfer. Amazingly, it has the ability to project its pollen at a rate of 4 metres per second—more than 2,000 times the acceleration of gravity (p. 20). When an insect touches on an unopened flower, it triggers the firing of the pollen through the release of stored energy. The pollen then transfers to the insect which in turn moves on to another flower to cross-pollinate. Larger pollinators such as Bombus (Bumblebees) are required to initiate the opening of the flowers; although flowers that open by themselves are able to fire the pollen at a distance of about 1 metre to adjacent plants.[ii]

In “Treepedia,” we learn that Magnolia trees were among the first flowering species on the evolutionary scale (about 100 million years ago) and that they were and still are pollinated by beetles (p. 82). Magnolias developed hardened carpels (female reproductive parts) so they are able to tolerate the beetles’ chewing mandibles.[iii] The beetles are attracted to the large, strongly scented flowers as well as the pollen and other secretions. Pollen grains are readily captured by the insects’ hairy bodies—which are transferred to other flowers.[iv] Some gardeners may only think of bees as being pollinators and don’t think of the importance of beetles. Some other species that are pollinated by beetles here in Ontario include Asimina triloba (Pawpaw), Nymphaeaceae spp. (Water Lillies), and Lindera benzoin (Northern Spicebush).

In “Insectopedia,” the topic of seed dispersal, the term myrmecochory is explored. More than 4,000 plant species rely on ants for seed dispersal. Ants are attracted to the nutritious fatty seed coats called elaiosomes and take them back to their nests. The remaining unwanted parts of the seeds are discarded near the nests and subsequently germinate into new plants (pp. 155-156). Have you ever wondered how some new plants pop-up some distance from the parent plant? Species such as Sanguinaria canadensis (Bloodroot), Trillium spp., (Trillium), Scilla spp., (Squill), Hepatica acutiloba (Sharp Lobed Hepatica), Viola spp. (Violets), are just a few examples of plants that can spread with the help of ants.

These little books would make a nice gift for any curious gardener, amateur botanist, or nature enthusiast.


[i] Pedia series. Princeton University Press: https://press.princeton.edu/series/pedia-books

[ii] Edwards, J., Whitaker, D., Klionsky, S. et al. A record-breaking pollen catapult. Nature 435, 164 (2005). https://doi.org/10.1038/435164a

[iii] Evich, Philip. The Botany of Magnolias. Smithsonian Gardens. Online: https://gardens.si.edu/learn/blog/the-botany-of-magnolias/

[iv] Hooks, Cerruti R., and Anahí Espíndola. Beetles and Pollination. Maryland Agronomy News. Online: https://blog.umd.edu/agronomynews/2020/06/29/beetles-and-pollination/

The Fall of a Fall Favourite

By Lois Scott, Master Gardener

Sometimes it feels like my garden will never reach the ‘mature’ stage even though I have been gardening in the same spot for 36 years.  There are a variety of reasons for that, but one major one was my need to remove plants that are now considered invasive. “Invasive species are considered one of Canada’s greatest threats to the survival of our wild animal and plant life.  Invasive species kill, crowd out and devastate native species and their ecosystems”.  https://www.invasivespeciescentre.ca/learn.

So, who were the super villains in my garden?  I’m looking at you, Burning Bush (Euonymus alatus) and also you, Barberry (Berberis).  I was initially truly disappointed when I realized they needed to go but then my short attention span came into play and I was on to the next thing.  What new plants could I get to replace said villains?!!!  And they are environmental villains:

Burning Bush
Japanese Barberry

Burning bushes are certainly very visible at this time of year due to their intense red foliage, but Chokeberry (Aronia melanocarpa) makes a wonderful substitute for both Burning Bushes and Barberry.  They are native to Ontario, will grow up to 2.5 metres tall, have white flowers in spring and their fall colour is dramatic.  They will grow in moist or dry areas and they attract pollinators and songbirds.  There are actually many native shrubs that are very ‘ornamental’ and worthy garden additions.  https://www.inournature.ca/best-native-shrubs

Chokeberry (Aronia melanocarpa)

At the risk of blathering on about native plants, one small benefit for me is that if I choose a native plant that is not aggressive (rampant spreader etc) and is suited to the conditions of the site (right plant, right place) I won’t find myself having to hack out this year’s fan favourite that turns into next year’s invasive disaster.  Always a good thing for me and the wildlife and pollinators in my garden!

For Garlic Lovers Only … How to Grow and Harvest Garlic in Ontario

By Carol Anderson, Master Gardener in Training

Unlike many of our more tender vegetable and herb favorites, garlic prefers to spend the winter “contemplating” spring from a safe and protected spot in your outdoor garden bed. And the good news is that the timing is perfect – planting garlic in October, after the first frost (or two), is ideal for ensuring a healthy crop of garlic that will be ready for harvest the following summer (usually mid to end of July).

The reason for this is that garlic is considered a “winter annual” and exposure to the cold temperatures ensures proper bulb development. The cold of winter, also known as vernalization, prompts the clove to break open after a period of dormancy. However, the garlic cloves that you plant (also called “seed stock”) must be planted to the correct:

  • Depth: to ensure that they are insulated from extreme or harsh conditions, and
  • Distance: to ensure that the stock has enough room to multiply into large and healthy buds.

What you will need:

-small trowel
-garlic seed stock (*see special note)
-leaves or hay (as mulch)
-compost (recommended)
-pen and paper
-toothpicks (optional)

Planting Guidelines:

  1. Condition your Soil. Although garlic will grow in many soil types, adding 2 inches of compost and working this into your soil is recommended. A soil that can hold nutrients and water easily (making them available to your plants) will improve your overall yield.
  2. Split the garlic bulb into the seeds while trying to keep as much of the soft shell on each of the cloves.
  3. Make a “map” of your garlic field on the ground with either toothpicks or the end of your trowel marking where each garlic “seed” will be placed. It is recommended that each seed (clove) is planted ~6” apart and ~4” deep in rows that are 10” apart. (Note: the clove should be planted to a depth that is 4 X the length of the clove – e.g. 4” for a 1” clove).
  4. Place the clove with the pointy side up in the 4” deep hole and cover gently with soil.
  5. Make a paper “map” of your garlic field so that you remember where each garlic bulb will be growing in the Spring.
  6. Cover our garlic field with 12-18” of leaf or straw mulch.

Growing and Harvesting Recommendations:

  1. In the Spring, you may need to remove or refresh the mulch. It is recommended to keep the garlic field mulched with a few inches of mulch to keep the moisture in and reduce weed growth.
  2. Using a standard garden hoe, weed frequently between the rows to uproot any early weed growth.
  3. Most garlic varieties produce a garlic “scape” – a thin curly green end of the plant. If the scape is left on the plant, energy will go to flower formation, instead of bulb growth. Remove the scape immediately after it has curled (see below) by cutting or snapping it off (see Special Note below).
  1. Harvest the garlic by using a garden fork or spade – loosen the soil 4-6 inches around the bulb and then lift the entire plant with bulb attached gently from the soil. (Note: garlic is usually ready to harvest in July when some of the leaves have begun to turn brown. Leaving them too long will allow decay. It is recommended, however, that during a moist summer a “test” is done by digging up a bulb before the leaves start to brown to avoid premature decay).
  2. Tie 5-10 garlic bulbs together in a bunch with garden twine/hemp and hang to dry/cure for 2-3 weeks in a dry well-ventilated area.
  1. Cut the dried garlic stem close to the bulb using garden cutters and remove the dried roots close to the bulb using kitchen scissors. Store the bulbs in a cold cellar or cool dark location for later use (never in the refrigerator), keeping as much of the sheath/covering of the bulb intact as possible. Garlic can be stored for up to one year in the right conditions.
  2. Enjoy!!!!

Special Notes:

Garlic Stock: Do not use imported garlic purchased from the grocery store as this could introduce unwanted diseases into your garden. Garlic stock (or seed garlic) can be purchased from local growers near you….and the good news…once you grow your own…you will have an endless supply of “stock” acclimatized to your own growing conditions.

Spring Planting: Garlic can be planted in the spring. However, you must keep your “stock” in cold storage prior to spring planting to ensure that the bulbs experience a prolonged cold period to stimulate flowering/bulb development.

Garlic Scapes are not garden waste, they are delicious in salad…and they make a deliciously potent pesto!!!! Try this garlic pesto recipe out.

Sources:

Garlic Growers of Ontario
Garlic Growers Association – Toronto Garlic Festival
The Old Farmer’s Almanac

Reflecting on the Past Season

By Marilyn Homewood, Master Gardener

The frost has made its first appearance marking the end of the summer growing season.  Before plunging headlong into bulb planting, I find it valuable to use this time to take stock of the past season as it serves to help me plan for next year (although I must admit I have already submitted a lengthy list of dahlia tubers for next spring).  I find it helpful to keep a gardening journal throughout the year for reference purposes and it becomes an important part of this process. There are many entries especially in spring when I am propagating, not so much in the summer but I always do a fall summary.  This written record has served me well over the past few years.  I also take this opportunity to look back over the photos I took throughout the season. They sometime remind me of just how much I enjoyed a certain plant.  One plant whose value seems to fade from my memory is sweet peas. Time consuming to grow, somewhat fleeting in our climate, I am always ready to drop them from next year’s list until I look at the photo.  Then I recall just how much I enjoyed their appearance and scent!!

Successes: It can be hard to see all the good things that happen when you are in the midst of seed starting, weeding, transplanting and harvesting.  I tend to dwell on what is not working (don’t all gardeners?) and often pass over the good stuff.  Evaluating the successes allows you to repeat or expand on your wins for next year.  This year I grew lisianthus (prairie gentian) for the first time.  It grew well in our climate and produces a bloom that is both attractive and long lasting.  It has continued to push out buds and I am still cutting it for the vase.  Next year, I will try starting it from seed, grow more of them and also plant some in the landscape for bloom from August to frost.

Challenges: Identify what did not go well and try to ascertain what the problem was and if it can be addressed.  Sometimes things just don’t work in your situation and its worth evaluating if the time, effort and money is worth allocating to this endeavor.  After a couple years of trying, I have decided to give up on ranunculus.  They are labour intensive as they require pre-sprouting in March with planting out in April under hoops and frost cloth.  Growth was great on the plants however each time a plant budded up an unidentified varmint would come in and make off with the flower bud.  So it’s a choice between adding rabbit protection to the already busy growing regime or devoting the resources elsewhere.

Future Opportunities: Always be on the lookout for possibilities for next season.  Whether it is a major project or a plant acquisition, this is a good time to firm up ideas.  I watch a lot of different types of gardening webinars and do a lot of reading and am always jotting down plant ideas that might work for me.  This is a good time to evaluate that list and based on available space, determine what to try for next year.  If it involves propagation, it might mean acting now.  I have decided to expand my planting of perennial poppies and am going to take root cuttings for the first time which will be overwintered in my extension.  With any luck, I will have new plants for next spring.

Try investing in a few hours musing over you garden and you reap the rewards next year.

https://extension.psu.edu/evaluating-the-garden

https://www.canr.msu.edu/news/garden-health-evaluation-part-1

Insect Galls on Trees

By Laura Gardner, Master Gardener in Training

I was out for a walk earlier this summer and noticed that a number of trees in my neighbourhood have lumps on their leaves, leaf stalks, shoots, or at the ends of their branches. At first glance you might be alarmed and think they are diseased, but many are the homes of tiny insects such as aphids, mites, sawflies, psyllids, and midges. They are often quite numerous and they come in different shapes and sizes. A gall is formed through the expansion of plant cells—similar to a tumour. This may be triggered by organisms such as viruses, bacteria, fungi, nematodes, or insects. Insects induce the galls through actions such as oviposition (inserting the egg into the plant tissue), the release of chemicals by the female and eggs, and through feeding. It is a shelter for the young and protects them from predators. While sometimes causing leaf deformity, in the majority of cases, galls are a cosmetic concern and do not harm the tree.

Here are a few you may encounter that are caused by insects:

These variable shaped galls specific to Populus deltoids (Eastern cottonwood) are the homes of an aphid called Mordwilkoja vagabunda (Poplar Vagabond Aphid). New galls are a light colour but become darker with age. Each gall releases upwards of 2,000-winged offspring in mid-July to early August. Sounds like it could have been the inspiration for a science fiction novel or movie.

Rabdophaga strobiloides (Willow Pinecone Gall Midge) are found at the ends of branches of various Salix spp. (Willow). What is amazing about these structures is that up to 31 different insects use them for their young—residing in the papery-like folds of the gall.[i] The galls are also frequently predated by birds and parasitic wasps.[ii] The biodiversity that Willows support is wide and for this they are known to be keystone species—they are also among the earliest plants to flower in the spring and support emerging pollinators like Queen Bumblebees.

Euura proxima (Willow Redgall Sawfly) frequents certain Salix spp. (Willow). This gall can be identified by its red bean-like appearance on the leaves. Sawfly larvae are often mistaken for Butterfly or Moth caterpillars. They can be distinguished by the number of abdominal prolegs: the former has six or more and the latter five or less.

Pachypsylla celtidismamma (Hackberry Nipple Gall Maker) is a Psyllid (Jumping Plant Lice) that forms round, often clustered galls on the underside of Celtis (Hackberry) trees. Adults spend the winter in cracks of the tree bark itself or even in nearby buildings.

The Eriophyid mite, Vasates quadripedes (Maple Bladder Gall) forms on Acer spp (Maple) such as the upper leaves of this Acer x freemanii ‘Autumn Blaze’ (Freeman Maple ‘Autumn Blaze’). The galls first appear as green, then turn to red, and finally black. The mites overwinter in the creases of the tree’s bark.

So, if your trees have strange growths on them, check out the wonderful web site https://gallformers.org. There you can identify galls by their specific host trees, the form of the galls, and their location on the trees. You can also narrow your search down to those that occur in Ontario. Another good site for identification is https://www.bugguide.net, a comprehensive database of insects for the US and Canada.


[i] Willow Pinecone Gall Midge. Minnesota Seasons. http://www.minnesotaseasons.com/Insects/willow_pinecone_gall_midge.html#:~:text=It%20consists%20of%20numerous%2C%20stunted,shape%20resembles%20a%20pine%20cone

[ii] Van Hezewijk, B.H. and Roland, J. (2003), Gall size determines the structure of the Rabdophaga strobiloides host–parasitoid community. Ecological Entomology, 28: 593-603. https://doi.org/10.1046/j.1365-2311.2003.00553.x

Jumping Worms & Invasive Species Awareness

By Christine Freeburn, Master Gardener

Master Gardeners have been talking about the importance of controlling invasive species for years. Purple Loosestrife, Giant Hogweed, Buckthorn, Garlic Mustard and Dog-strangling Vine are on a long list of Invasive Plant Species.

You can check the list out at www.invasivespeciescentre.ca  or www.invadingspecies.com

But there are more than just invasive plants. There are also invasive insects like Spongy Moths and Emerald Ash Borer. There are invasive fish and invertebrates like Zebra Mussels and Asian Carp. We have invasive pathogens like Dutch Elm disease (Dutch Ed: “Identified by the Dutch, not CAUSED by the Dutch”). And just recently, we have begun to hear about Wild Pigs and Jumping Worms.

I took part in a webinar presented by the Royal Botanical Gardens on Jumping Worms (JWs) earlier this month. Two speakers, Brook Schryer from the OFAH who works with the Invading Species Awareness Program and Dr. Michael McTavish with the Smith Forest Health, University of Toronto, spoke about the need to be aware of jumping worm sightings in Ontario. They gave information about Eddmaps.org where interested citizens can share their own findings. You can find a recording of this event at https://www.youtube.com/user/royalbotanicalgarden

Now is a good time to find JWs as they are adults at this time of year and can be better identified.

Jumping Worms are an invasive species of Asian worm that are slowly moving their way from the United States. They are voracious eaters and can consume much of the compost, topsoil and debris that lays on forest floors. They leave behind worms castings that are loose and crumbly similar in appearance to coffee grounds. They are often found in wet and shady spots and castings are spread evenly rather than in clumping piles. The castings can be a thin layer or can be 10 cm deep. It will appear as though the ground has been previously dug as the soil will be loose. Jumping worms are distinguished by their thrashing behaviour when moved or picked up. They have also been known to amputate their tails as a method of evasion from predators. There are usually many worms found together close to the soil surface. The worm body is smoother than our earthworm and tends to be more gray than red. The milking band or clitellum goes all the way around their body. Although the worm dies in the cold winter months, their cocoons survive, becoming juvenile worms in May and June and adults in July.

Left on their own, these worms can spread up to 10 meters per year. However, without human help, the spread could happen much quicker.

Research in Canada is happening, but we should all be aware of the dangers of this invasive species, and take precautions.  We just need to think of the days before Phragmites showed up in every wetland and ditch in our area. Awareness and education are important.

Check out the EDDmaps.org site where you can see where actually sightings of invasives have been recorded. The two presenters encouraged us to go out and search for signs of the Jumping Worm and report it to the EDDmaps, whether a positive sighting or a negative one. You can also call the Invading Species Hotline at 1-800-563-7711 if you have a concern.

My Newest Favourite Flower

By Marilyn Homewood, Master Gardener

One of the new plants that I tried this year was Lisianthus (Eustoma grandiflorum) also known as prairie gentian.  Lisianthus are flowering plants native to northern Mexico and the Great Plains in the United States and as with most prairie plants, they love the heat and are quite drought tolerant.  I thought they just might work in my growing conditions.  The plants are hardy in USDA zones 8 to 10 and are grown as annuals here in Ontario.  Their flowers come in a wide range of colours, are double or single, can be very ruffled and are reminiscent of a rose.  They produce multiple buds on a single stem and one stem can bloom over a 3 week period.  A single stem will last around 2 weeks or more in a vase.  Plants bloom around late July/August and if pruned back when finished, a second smaller flush should bloom in September.  What a treat in August when almost everything else is flagging in the summer heat to have this beauty bloom! A welcome sight in that period before the dahlias really get going.

Is there a down side?  Lisianthus has a bit of a reputation of being difficult to grow. They are very slow to germinate and grow.  Here in Ontario, seeds should be started in early January. I can’t speak to that personally as I was able to purchase plugs in April in order to give the plants a try.  I will attempt to start seed this winter.  There are Lisianthus seed starter groups on line where lots of information and assistance.

Note that these blooms had been in this pot for 2 weeks when the photo was taken!

Seed/Variety Selection

Lisianthus produce tiny seeds hence most of the seed that you purchase is coated to make handling easier (NB coated seed does not store well from season to season).  A number of different series are available and varieties of lisianthus are grouped by bloom season (similar idea to the classifications of snapdragons).  Flowering is stimulated by three factors; Temperature (warmer temperatures accelerate flowering),Light intensity (high light intensity accelerates flowering), and Day length (long days accelerate flowering). By using varieties from Group 2 and Group 3 you can have blooms over a longer period of time as they have different bloom periods.

Cultural Requirements

Lisianthus is a heat-loving plant but it doesn’t like direct afternoon sun. Ideally it should have full morning sun and part shade in the afternoon. The lowest temperature lisianthus can survive outdoors is -12°C and many growers feel that the plant benefits from being planted out before the last frost in order to get their roots established. Lisianthus prefers to have an even amount of water on a regular basis. If it doesn’t rain often, the plant will need to be watered for the best performance.  I neglected to do this (got busy with dahlia issues) and the lack of water was reflected in stem length and bud count but the flowers seemed unaffected (I still had 5-6 buds on each stem). The blooms were wonderful. Recently I visited someone who had watered their plants: they were twice as tall and had even more buds than mine.  Lisianthus can be subject to botrytis hence it’s important to water at the base of the plant. Well-draining soil with a neutral to slightly alkaline pH is preferred. These plants are happy with a feed of compost and if you’re feeling keen, the occasion feed of fish fertilizer. 

Next years seed starting should prove interesting.  Of course, if it doesn’t work there are always plugs!

“Before the seed there comes the thought of bloom” E.B. White

Resources

Armitage, A.M. and J.M. Laushman. 2003. Specialty Cut Flowers, 2nd Edition. Timber Press, 586 pp. 

Lisianthus Seed Starters Group, https://www.facebook.com/groups/198146460815037

Think Spring!

By Cheryl Harrison, Master Gardener

At this time of year, it is difficult to get excited about spring when we know what must come first … fall then winter!  However, late summer is exactly the time to think about spring bulbs because they must be planted in the fall in order to bloom the following spring.

As with all plants, you need to take into consideration the amount of light needed, soil and moisture requirements.  Most bulbs require full sun to part shade, well drained loam soil and watering when dry.  Note that bulbs may rot when over-watered. 

Some sources suggest adding bone meal to the planting hole.  Bone meal adds phosphorus to the soil which may encourage bulb growth but may also harm some of the other beneficial soil constituents.  It is prudent to test your soil first. 

Plant bulbs with the pointed end up and to a depth of 2-3 times the diameter of the bulb.  You may sprinkle blood meal over the planting site or cover with chicken wire to discourage squirrels and chipmunks from digging them up.

Plant your spring flowering bulbs any time between September to December … as long as you are still able to work the ground. 

Spring flowering bulbs are lovely in a formal garden as well as in more natural settings. For naturalization of spring bulbs, please see Bulbs for Naturalizing.

Now the really fun part, what to choose!  Check at your local nursery to see what they have in stock and/or what they may be ordering in.  Choose large, undamaged bulbs.  It is also likely that your favourite on-line supplier carries spring flowering bulbs.  I would suggest that you do this well before you plan to plant to ensure that you are able to get what you want.

Tulips – We are all familiar with the large colourful, showy tulips.  Their blooms may be cup shaped, fringed, double or ruffled.  This fall, I plan to plant some, new-to me species tulip bulbs.  While species tulips are smaller than the tulips that we are most accustomed to, they are colourful, very hardy and have a more open flower. 

Hyacinth – You can not beat the magnificent fragrance of hyacinth blooms in the spring.  They come in several colours, single or double and are accompanied by strong, strappy leaves.  Hyacinths also produce nectar so provide food for some of our early foraging pollinators.

Narcissus – The spring flowering bulb, in the genus Narcissus, is more commonly called a daffodil.  Bloom colours range from bright yellow to cream to white and combinations of these colours.  Daffodils are cheerful flowers.  I always smile when I see them especially in a natural setting.

Crocus – Crocus “bulbs” are actually corms.  What is the difference??, check here.  These are probably the first of the fall plantings that you will see in the spring. Crocus blooms are tube shaped and come in various colours.  The plant is low growing and does well when naturalized.

The above are some of the more often seen spring flowering bulbs but there are more.  Please see Landscape Ontario  for additional suggestions.

Outcompeting Invasive Plants, Part II

By Laura Gardner, Master Gardener in Training

This article was published in err a couple of weeks ago, and is being republished today as a corrective measure. Apologies. -Ed.

Back in a June post[i], I referenced the Ontario Native Plant Council’s best management practices for Alliaria petiolata (Garlic Mustard).[ii] In it they referred to certain native plants that can be used to outcompete it. I would like to mention one other that I am fond of having in my garden. Packera aurea (Golden Groundsel) has a diminutive orange inflorescence and is native to the Peterborough area. It can be aggressive as it reproduces through rhizomes and adventitious shoots on the stems. It is better situated in moist soils and so it may be more subdued in a drier location. In her blog, The Humane Gardener[iii], Nancy Lawson discovered that when she inserted clumps of Golden Groundsel into patches of Garlic Mustard, the latter quickly became surrounded. Garlic Mustard is known to be allelopathic and inhibits the growth of some plants. However, Golden Groundsel does not appear to be inhibited by it.

Golden groundsel, Packera aurea

Anemonastrum canadense (Canada Anemone) is a beautiful vigorous native ground cover that performs well in sun to shaded environments; although it can develop brown leaves in more arid conditions. I am using it to limit the advance of Campanula rapunculoides (Creeping Bellflower). The intent is to envelope it so that it is unable to photosynthesize, grow more foliage, and store energy in its roots. One might argue that this is simply a matter of replacing one problem with another. While it is true that Canada Anemone can be overwhelming, it may be limited by deadheading the flowers, removing rhizomes, adding mulches, and by installing edging below the soil surface. As a native plant, it supports pollinators such as miner bees, sweat bees, and hover flies. The Xerces Society notes that it supports “conservation biological control.”[iv] This is a plant that attracts beneficial insects to your garden which in turn will help control other insects that damage your other plants.

So far, the Creeping Bellflower’s development has been slowed but there are still some basal leaves within the patch and at the perimeter. Right now, it is still a team effort: Canada Anemone and me.


[i] Outcompeting Invasive Plants: Part I. https://peterboroughmastergardeners.com/2022/06/13/outcompeting-invasive-plants-part-1/

[ii] Garlic Mustard (Alliaria petiolata): Best Management Practices in Ontario. Ontario Invasive Plant Council.  https://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/07/OIPC_BMP_GarlicMustard.pdf

[iii] How to Fight Plants with Plants. The Human Gardener. Online: https://www.humanegardener.com/how-to-fight-plants-with-plants/

[iv] Habitat Planning for Beneficial Insects: Guidelines for Conservation Biological Control. Xerces Society. http://www.xerces.org/publications/guidelines/hab

Outcompeting Invasive Plants, Part II

By Laura Gardner, Master Gardener in Training

This article was published in err a couple of weeks ago, and is being republished today as a corrective measure. Apologies. -Ed.

Back in a June post[i], I referenced the Ontario Native Plant Council’s best management practices for Alliaria petiolata (Garlic Mustard).[ii] In it they referred to certain native plants that can be used to outcompete it. I would like to mention one other that I am fond of having in my garden. Packera aurea (Golden Groundsel) has a diminutive orange inflorescence and is native to the Peterborough area. It can be aggressive as it reproduces through rhizomes and adventitious shoots on the stems. It is better situated in moist soils and so it may be more subdued in a drier location. In her blog, The Humane Gardener[iii], Nancy Lawson discovered that when she inserted clumps of Golden Groundsel into patches of Garlic Mustard, the latter quickly became surrounded. Garlic Mustard is known to be allelopathic and inhibits the growth of some plants. However, Golden Groundsel does not appear to be inhibited by it.

Golden groundsel, Packera aurea

Anemonastrum canadense (Canada Anemone) is a beautiful vigorous native ground cover that performs well in sun to shaded environments; although it can develop brown leaves in more arid conditions. I am using it to limit the advance of Campanula rapunculoides (Creeping Bellflower). The intent is to envelope it so that it is unable to photosynthesize, grow more foliage, and store energy in its roots. One might argue that this is simply a matter of replacing one problem with another. While it is true that Canada Anemone can be overwhelming, it may be limited by deadheading the flowers, removing rhizomes, adding mulches, and by installing edging below the soil surface. As a native plant, it supports pollinators such as miner bees, sweat bees, and hover flies. The Xerces Society notes that it supports “conservation biological control.”[iv] This is a plant that attracts beneficial insects to your garden which in turn will help control other insects that damage your other plants.

So far, the Creeping Bellflower’s development has been slowed but there are still some basal leaves within the patch and at the perimeter. Right now, it is still a team effort: Canada Anemone and me.


[i] Outcompeting Invasive Plants: Part I. https://peterboroughmastergardeners.com/2022/06/13/outcompeting-invasive-plants-part-1/

[ii] Garlic Mustard (Alliaria petiolata): Best Management Practices in Ontario. Ontario Invasive Plant Council.  https://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/07/OIPC_BMP_GarlicMustard.pdf

[iii] How to Fight Plants with Plants. The Human Gardener. Online: https://www.humanegardener.com/how-to-fight-plants-with-plants/

[iv] Habitat Planning for Beneficial Insects: Guidelines for Conservation Biological Control. Xerces Society. http://www.xerces.org/publications/guidelines/habitat-planning-for-beneficial-insects