Category Archives: Invasive

Year in review: part 1

By Suzanne Seryck, Master Gardener

It is a beautiful fall day as I’m writing this blog, blue sky and temperature around 20 degrees. I have just finished the last jobs before putting my garden to bed for the winter. The last of my 30 or so bags of leaves have been mulched and put onto the gardens, apple trees have all been wrapped to prevent rabbits and squirrels from eating the bark off of them, and I have emptied the rain barrels onto the trees, shrubs and fruit bushes.

Time for both a well earned rest and for me to put together my garden review list for this year. All season long I jot down notes of anything that is working, not working or something that I need to concentrate on or remember for next year and then I compile it into one list. This year I’m going to share my list in this blog, although the list is a little long for just 1 blog so I’ll split it in 2 parts.

I don’t plant many annuals in my garden–a couple of urns out front with 2 hanging baskets, and some large pots at the back. I love the colour that annuals provide all season, but they typically need more watering than I like to do, and I find them expensive. Last year I overwintered some cuttings I took from both my coleus and sweet potato vines as well as overwintering the purple fountain grass. All the cuttings worked great, and in the spring after hardening off I was able to plant them into my pots and urns; they grew really lush and full. The green potato vine was much stronger and more robust all season than either the purple or copper plants, however the purple fountain grass grew back very slowly never really getting the vibrant purple colour back. This year I’ve taken even more cuttings from my coleus along with the green and purple sweet potato vine. However, I decided that I would rather spend the money on new fountain plants each spring.

Urn in author’s garden

I have 2 large compost piles that I use all year, filling to the top with leaves and then burying food scraps the rest of the year. This year I religiously turned the one pile every couple of weeks starting as early as I could and was rewarded with compost all gardening season. In the second pile though, a couple of errant zucchini plants started growing producing lush growth and lots of flowers and I thought ‘why not leave them?’. I’m sure you can guess the rest, not a single zucchini and I was not able to use any of the compost all season. Note to myself if anything accidentally grows out of the compost next year, turn it back in.

For the first time this season I grew Sicilian zucchini, now I didn’t actually realize I had bought this variety until it started growing up the espaliered tree fence and growing 2-3 foot long zucchinis. I’m definitely going to grow them again next year, although in a different location. When the frost finally killed off the plants and we pulled them off the fence, the wires were no longer taut and needed some tightening. Another point to note is that the zucchinis were consistently eaten throughout August and September when they were barely an inch or two longer. I’m not sure why that only happened later in the summer, maybe the squirrel or rabbit population doubled when I wasn’t looking. I’m thinking of placing bags over the fruit as it is growing, hoping by the time it gets to a foot or more it won’t be quite so attractive to predators.

I tend to leave my perennials to self seed as I love growing plants from seed; it is probably one of my favourite things to do in the garden. I have set aside a nursery plot and any seedlings I find in the garden I move into the nursery. Unfortunately this year I noticed a definite increase in the number of swamp milkweed, verbascum and New England asters seedlings. Now I love these plants, but they are taking over both my garden and my garden paths. I grow Verbascum nigrum which is a beautiful stately plant with either yellow or white flowers. It tends to be a short lived perennial but as it grows profusely from seed, I always have a few plants in my garden. Swamp milkweed is a host for the monarch butterfly; in my garden I have both pink and white flowering plants. They prefer moist to wet soil and because my soil is dry, they are also short-lived. Not so the New England aster; this is a native aster which grows 4 to 5 foot with beautiful purple blue flowers, however it can get very large in just a couple of years. Next year I have to dead head these plants, leaving only a couple to go to seed, which I can then harvest and plant in a specific area of the nursery.

Verbascum in author’s garden; this one plant bloomed all summer.

On the positive side, I was surprised by an abundance of aquilegia (commonly known as columbine) in my front garden that I was not expecting. I had left the seedlings thinking from a distance they were meadow rue, only to be surprised by this showing:

Aquilegia in author’s front garden

Aquilegia are one of my favourite plants, but I tend not to grow them as I find in my garden they are eaten by slugs. One day I have a beautiful plant in full flower, and the next day just a few stems still standing. I’ve slowly been replacing them by meadow rue, which for me has a similar lacy look, which I like when paired with hostas and brunnera. Slugs don’t seem to like meadow rue, but for some unknown reason this year, they also left the aquilegia alone. Based on this I have since ordered some seeds from the native aquilegia, Aquilegia Canadensis, which has beautiful red and yellow flowers and also likes sun to part-shade.

And finally the dreaded creeping charlie in my lawn. I have a small lawn which I have been overseeding with clover in my attempt to make the lawn healthier and more low maintenance. Clover has a lot of great benefits in a law including growing in poor soils. Clover is a nitrogen fixing legume, so it will improve the health of the soil and the surrounding grass, needs less watering and mowing, attracts beneficial insects, and crowds out weeds. Unfortunately though it does not crowd out the creeping charlie and actually seems to co-exist with it harmoniously. The recommended solution in a lawn is to hand pull the creeping charlie and because it grows by rhizomes which then root into the soil, removing all parts of the plant can be very time consuming. I have heard that it is easier if you soak the ground first or weed after it has rained. Note to myself, recruit an army to help me after each rainfall in the spring, either that or learn to love it!

Invasive Species

By Sharleen Pratt, Master Gardener

According to the Ontario Invasive Plant Council, an Invasive Species is an alien species whose introduction or spread negatively impact native biodiversity, the economy and/or society, including human health.

Therefore, an invasive plant species is often a plant that has been brought into Ontario from another country, possibly for medicinal reasons or as an addition to one’s garden.  For various reasons, it becomes aggressive, spreads quickly and often displaces native plants.

Here is a detailed description of five invasive species that could show up in your garden.  They are all Category 1 Invasive as designated by the Credit Valley Conservation described as species that exclude all other species and dominate sites indefinitely. Plants in this category are a threat to natural areas wherever they occur because they tend to disperse widely (for example, through transport by birds or water). They are the top priority for control but control may be difficult.

Rhamnus cathartica
Common Name:  Common Buckthorn, European Buckthorn Common-Buckthorn

Height:  Up to 10m tall
Type of Plant:  Deciduous Shrub or small tree that is fast growing and short lived
Leaves:  Smooth, dark green leaves with slightly serrated leaf margins, somewhat elliptical and arranged in opposite to sub-opposite pairs along the stem.  A sharp thorn can be found on the end of most branches.
Flowers:  Flowers occur in the spring.  They are yellowish/green, with four petals in clusters of 2 to 6 near the base of the petioles.  They are small and inconspicuous.
Fruit:  Produces clusters of berry-like globose black fruit in late summer and fall; although it’s mildly poisonous, birds and other wildlife eat the fruit and disperse the seeds.
Culture:  Can thrive in a wide range of soil and light conditions.  It is shade tolerant.
Invasion Pathway:  Introduced from Eurasia to North America in the 1880s for ornamental landscaping.  It was widely planted for fencerows and windbreaks in agricultural fields.  The large number of seeds are spread by birds and animals.
Impacts:  Habitat destruction and because it leafs out early, it is a danger to native species.  It also alters the nitrogen levels in the soil. The soybean aphid, an insect that damages Ontario soybean crops, can use buckthorn as a host plant to survive the winter.
Control Measures:  Physical removal, herbicides, fire, girdling

Alliaria petiolata
Common Name:  Garlic Mustard
Garlic Mustard
Height:  30 – 100cm tall
Type of Plant:  Biennial Herb in Mustard Family
Leaves:  In First Year:  Leaves are dark green, cordate shaped with crenate margin edges. In Second Year:  Leaves are alternate on a larger stem with somewhat doubly serrated edges.  The lower leaves on the stem are broad, cordate shaped and up to 10cm across.  The upper leaves on the stem start to narrow.
Flowers:  In Second Year:  Four white petals appear, arranged in cross shape.
Fruit:  In Second Year:  The fruit is erect, slender, 4-sided pod, green, maturing pale grey-brown, two rows of small shiny black seeds.  Hundreds of seeds can be produced from a single plant.
CultureAlliaria can grow in a wide range of sunny and fully shaded habitats, including undisturbed forest, forest edges, riverbanks and roadsides.
Invasion Pathway:  Introduction for perceived medicinal value as a disinfectant, a diuretic and sometimes being used to treat gangrene and ulcers.  It was also planted as a form of erosion control. European settlers also used it as a garlic type flavouring.  Seeds can remain in the soil for several years and still be able to germinate.  Hundreds of seeds produced from one plant.
Impacts:   Alliaria forms dense stands, replacing native plants and has been implicated as partial cause for endangered status of our native wood poppy (Stylophorum diphyllum), American ginseng (Panax quinquefolius) and our provincial Trillium (Trillium cernuum).  It is toxic to larvae of certain butterfly species that lay eggs on the plant.
Control Measures:  Removal by hand, mowing or burning in early spring before flowering.  Should always be bagged and burned.

Cynanchum louiseae and C. rossicum
Common Name:  Dog Strangling VineDog Strangling Vine

Height:  2m high
Type of Plant:  Twining Vine
Leaves:  Oval with a pointed tip and grow opposite
Flowers:  Pink to dark purple star-shaped flowers have five petals
Fruit:  Produces bean-shaped seed pods that open to release feathery white seeds in late summer
Culture:  Prefers open sunny areas but can handle some shade. More dominant in meadows or woodland edges.
Invasion Pathway:  Introduced in the U.S. in the mid 1800s for use in gardens. Produces 28,000 seeds per square metre.  Seeds spread by wind and new plants also can grow from root fragments
Impacts:   Forms dense stands that overwhelm and crowd out native plants and young trees, preventing forest regeneration.  Invading ravines, hillsides, stream banks and utility corridors.  Leaves and roots may be toxic to livestock.
Control Measures:  Digging is most effective.  Hand pulling is not recommended as the plant will send up multiple shoots.

Vinca minor
Common Name:  PeriwinklePeriwinkle

Height:     Up to 15 cm tall
Type of Plant:  Evergreen herb that exhibits a trailing mat with a medium growth rate.
Leaves:  Lance shaped, shiny, evergreen with a subtle white mid vein.  They are opposite along stem.
Flowers:   Showy blue/purple with 5 fused pin-wheel like petals and a short tubular throat that bloom in late spring.
Culture:  Various soil types.  Found in forests and along streams, roads and wetlands.  Typically associated with residential gardens.
Invasion Pathway:  Introduced as a garden ornamental and medicinal herb.  It spreads by means of arching stolons, which root at the tips.  Grows most vigorously in moist soil with only partial sun, but it can grow in the deepest shade and even in poor soil.
Impacts:  Still sold as a groundcover which is a major concern.  It spreads quickly and is a threat to native biodiversity.
Control Measures:  It can be pulled, raked, or dug up, though re-sprouting will likely occur.  It can also be cut or mowed in spring during its rapid growth stage.

Aegopodium podagraria
Common Name:  GoutweedGoutweed

Height:  2m tall
Type of Plant: Herb
Leaves:  Compound leaf with serrated edges, can be non-variegated or variegated green and white, alternate
Flowers:  Flat topped ‘umbrella like’ flower head with many small white flowers in late spring held above the foliage on leafy stems (which look similar to Queen Anne’s Lace).
Culture:  Various habitat.  Full sun to part shade.  An escapee from residential gardens into forested areas.
Invasion Pathway:  Goutweed seeds require recently disturbed soil and a sunny location to survive after germination. For this reason, Goutweed does not have much success reproducing by seed in forest ecosystems. However, even one established plant can create a large colony by spreading through its aggressive rhizomes.
Impacts:  Forms dense patches that displace native plants.
Control Measures: Because it has limited reproductive success by seed, small patches of Goutweed can be easily controlled by digging up the plant (with careful attention given to removing the entire rhizome) or covering with a tarp or weed barrier for at least one growing season.

A reliable resource for invasive species is the Ontario Invasive Plant Council

Spring Flowering Bulbs

By Sharleen Pratt, Master Gardener

Charles Dickens said “Nature gives to every time and season some beauties of its own”. Who can deny that spring-flowering bulbs are a promise of warmer temperatures and hopeful thoughts? Knowing the bulbs will emerge from the near frozen ground helps us to get through the bitter winter. They should be planted now in order for you to be rewarded with wonderful colour in early spring. They can stay in the ground year after year. There are several varieties of bulbs to choose from. The following are some of the more recognizable ones.

thumbnail_tulipsTulips are to Turkey and Central Asia. In the 1600s, they made their way to the Netherlands. Tulipmania took hold in the 1620s and tulip prices skyrocketed. A single bulb could be worth as much as an average family farm. The market collapsed in 1637, but tulips remain widely grown in the that country. Canadians liberated much of the Netherlands during the final months of the Second World War. More than 7,200 Canadians were lost in that conflict. The Dutch have gifted Canadians with 20,000 bulbs a year since that time and they are used in Ottawa’s now famous Canadian Tulip Festival every May. This year marks the 75th anniversary of liberation and the Dutch royal family will mark the celebration by thanking Canadians this year with a gift of 100,000 tulip bulbs. If you want to join the celebration, you can purchase your own Liberation75 tulips for $15.00 through the Royal Canadian Legion. By purchasing the bulbs, you will also be entitled to win a trip to the Netherlands. To place an order visit the Royal Canadian Legion.

There are hundreds of cultivars of tulips; early, mid and late blooming. They need a sunny location with soil that is well-drained and sheltered from the wind since they can be easily broken. Six weeks are needed for the foliage to die back in order to put energy back into the bulb. A rainy spring is bad for success with tulips. Some of the ‘old fashioned’ tulips are Darwin and Triumph. They are very reliable and come back year after year. Squirrels love tulips, so to deter rodents, mix tulips and daffodils together in order to get the scent of daffodils on the tulips. You can also try hen manure which comes in a pellet form. You could use barberry cuttings or crushed egg shells in and around the hole. Others have had success with plastic snakes. Also, squirrels won’t dig past their peripheral vision, so plant at least 6 – 8” deep. You could also try laying a flat board on top and remove it when the ground is frozen.

DaffodilsDaffodils and narcissus bloom earlier than most tulips. Spring sun is needed and they like soil that is well draining or they will rot. Oxalic acid on the bulb make them unpalatable to rodents. ‘Tete a tete’ is a mini daffodil that is very fragrant and also good for cut flowers. However, never include daffodils with other flowers in a vase as they have a sap that will cause the other flowers to wilt.

IMG_4638Alliums are ornamental onions. Most of the varieties bloom in June. They need free draining soil with 6 to 8 hours of sun. They make lovely dried flowers. It is best to plant alliums amongst other plants as the foliage is not desirable.

Muscari or grape hyacinths are amazing small bulbs known as minor bulbs. Snowdrops are also minor bulbs and are the first to emerge, often pushing up through the snow.

Snow crocus are an early blooming crocus and work well in a lawn as they bloom before you need to cut the grass. Dutch crocus are good for forcing and are bigger than snow crocus and tend to bloom a little later in the spring.

Beware of Scilla or Spanish blue bells! They are a small bulb and multiply prolifically, and although they are very pretty, they now sit on the invasive list. Scilla siberica is on the Highly Invasive category of this list put together by Credit Valley Conservation.

Bulbs can also be planted in pots and put in a cool area over the winter. This way, they can be brought in and forced to bloom early. Who wouldn’t be happy with a large pot of beautiful colour after a long hard winter. More information on forcing spring bulbs can be found in this article by Dugald Cameron in Garden Making Magazine.

Happy Planting!

Dog Strangling Vine

by Judy Bernard, Master Gardener

While taking a walk along one day along one of the lane ways along Crowe Lake, I spotted Dog Strangling Vine. It was because of the flowers that I recognized it.  They are very small, 5 to 9 mm long, star shaped and pink to dark purple in colour. The vines grow 1 to 2 metres long and will twine around structures, other plants or each other. The leaves are oval with a pointed tip, 5 to 9 cm long and grow on opposite sides of the stem. The flowers develop into a bean shaped pod filled with feathery seeds that are dispersed in late summer (similar to the milkweed pod, but much narrower).

DSV

The problem with dog strangling vine is that it can form dense stands that can overcome and force out other plants. Its leaves and roots are toxic to animals. It threatens the Monarch  Butterfly which will lay its eggs on the plant, but the larva cannot develop. (It’s related to milkweed, a plant necessary for the Monarch Butterfly.)

image1

I contacted the municipality and they have no program for its control, so it’s up to the individual property owner to be aware of it and to control its spread.

The Ontario Invading Species Program has information of how to control its spread.

If you already have some on your property, check out Best Management Practices. This also is from the Ontario Government.

 

Beware the Vigorous Plant!

By Suzanne Seryck, Master Gardener

Being the fairly recent owner of a small city garden, I find I no longer have the space for plants that either do not behave, need too much deadheading or pruning, spread too quickly becoming invasive, need to be staked or I’ve simply grown tired of. At least 90% of my garden is full of either fruit trees, shrubs, fruit bushes, perennials or raised vegetable beds. The remaining 10 or so percent contains a patio and a very, very small lawn that my husband tells me has to stay! So needless to say if I buy any new plants I have to give an existing plant or two away (thank heavens for plant sales).

I have a few plants in mind that I am considering replacing this spring so I have spent the last week or so looking through bulb and plant catalogues to see what is new this year. Catalogues are a great place to see what is new and exciting and also to fill the gardening void that generally happens this time of the year. However, I have heard both good and bad stories regarding plants purchased from these catalogues, so it is very much a personal choice. What I did notice though were the many different terms given to what I would describe as an invasive or ‘buyer beware’ plant, especially if, like me, you do not have a large garden.

allium

Allium were described as ‘carefree’. However, if you have ever tried removing hundreds of allium bulbs from a perennial bed that have self-seeded over many years ‘carefree’ is not a term I would immediately think of.

‘Vigorous’ is a term often used in these catalogues, which could mean either that the plant is strong, robust and grows well (which we would all like) or more likely that the plant grows very quickly and will take over your entire garden in a very short time. Examples of ‘vigorous’ plants include false sunflower (Heliopsis helianthoides), knotweeds (Persicaria) and orange trumpet vine (Campsis radicans).

Baby’s breath (Gypsophila) is listed with the description that it ‘readily fills gaps’, whereas bee balm (Monarda) is described as ‘multiplying quickly’.

lily-14254_1280

Lily of the valley (Convallaria majalis), need I say more! I actually inherited this plant in my shade garden and I think I could be digging it out for a good few years. I really do love this plant, but it has to be in the right location and in a bed all by itself. Lily of the valley is described in one catalogue as ‘creating a carpet of flowers’ and in another catalogue as ‘growing fearlessly among tree roots’.

But I think the term most often used to describe a plant that might become invasive in these catalogues is ‘naturalizing’. When I think of naturalizing I think of beds or daffodils or bluebells, but then I am English so that might explain why. Plants included in this category are masterworts (Astrantia), mountain fleece (Persicaria amplexicaulis), false sunflower (Heliopsis helianthoides) and meadow rue (Thalictrum flavum).

Being an avid gardener, some may even say obsessive, there are not many plants that I do not like and all of the plants listed above I have at one time or another grown, and still do. But gardening with only a limited amount of space has changed the way I look at and select plants.

Weed Control

by Sharleen Pratt, Master Gardener in Training

Some of Mother Nature’s weedier creations can become a real nuisance in the garden because they rob other more desirable plants of nutrients, moisture and light. If they become established, they can be very difficult to control, therefore, it is highly recommended for the health of your plants, that you weed on a regular basis. The best time to weed is right after it rains as the weeds will be much easier to pull.

A weed is generally any plant that is not welcome in your garden! They are usually plants that can grow in any kind of soil, reproduce prolifically and interfere or compete with other more desirable plants. Many weeds have been introduced from another country and often become invasive. They can be very difficult to control and it is important that all gardeners try to prevent these particular plants from taking hold and spreading through their neighborhood.

Weed Identification can be intimidating! A few of the more common weeds, generally found in your lawn are:

BROADLEAF PLANTAIN, Plantago major (pictured above)

Broadleaf plantain is a perennial weed that spreads rapidly by seed and new shoots arising from the roots. Broadleaf plantain is distinguished by its rosette of dull green, oval leaves with thick green stalks, and its elongated spikes of tiny green flowers. Each flower is followed by a small egg-shaped pod with 5 to 15 tiny dark brown or nearly black seeds that are rather glossy. The flowers set seed from spring until late autumn. Broadleaf plantain is easily removed with a dandelion fork. It can be out-competed in a lawn by over-seeding and aeration.

COMMON CHICKWEED, Stellaria mediastellaria-media-846435_640

The common chickweed may be an annual, winter annual or perennial. They have small white flowers with 4 to 5 petals. They reproduce by seed and by horizontally spreading leafy stems that root at the nodes. Common chickweed will flower through the spring, summer and fall. One plant can produce 10,000 to 20,000 seeds. The seed remains viable for up to 10 years.  Hand-weeding is best when the seedlings are small. It can be reduced by over-seeding since chickweed doesn’t like a lot of competition.

PURSLANE, Portulaca oleraceaPurslane

Purslane is a summer annual, reproducing by seed. It has fleshy leaves and stem, which lie prostrate on the ground. The seeds in small capsules are black, kidney-shaped and extremely small. An average plant produces 60,000 seeds. Purslane is one of the most common weeds in gardens throughout Ontario. Though rarely producing roots from the stem, if even a small portion of the root of an uprooted plant touches the soil, it can grow a new root system and become established. It is easily pulled and dies at first frost.

CREEPING BUTTERCUP, Ranunculus repensbuttercup

Creeping buttercup is a perennial and reproduces by seed and runners. There are two common buttercups, one is a tall buttercup and the other is a creeping buttercup. The tall plant does not have runners and, therefore, reproduces by seed only. Both will flower in early spring to the end of July. Flowers are bright yellow, about 1 inch across. Each plant is capable of producing up to 250 seeds. The first leaves are kidney-shaped and somewhat hairy below. This weed is poisonous to grazing animals, and care should be taken to control it from spreading. Creeping buttercup survives best in moist location, so any improvement in drainage will help to control it. Persistent cultivation will also help, as well as constant mowing.

CREEPING CHARLIE or GROUND IVY, Glechoma hederaceaCreeping-Charlie

Creeping Charlie, also known as Creeping Jenny or Ground Ivy is a perennial which reproduces by creeping tangled rootstocks and also by seed. It is part of the mint family. The leaves are opposite and palmately veined. They have a bright green surface. The seeds are smooth and dark brown. The plant reproduces well through its surface runners. It has rapid growth in early spring and is a persistent plant whose leaves and stems stay green under the snow, allowing it to flower early. It flowers in spring around the same time as the dandelion. This plant spreads easily in a lawn, particularly in shady areas. Close mowing will help. If possible, be sure to dig out the small seedlings by hand in early spring. With large patches, heavy mulch or newspaper would help to kill an infestation.

FIELD BINDWEED, Convolvulus arvensisbindweed-2453936_640

Field bindweed is a perennial weed that spreads rapidly by seed and creeping roots. It is a hairless, twining, or trailing plant with deep, cord-like roots. There is an extensive spreading, underground root system. The creeping white rhizomes have been reported to grow up to 30m in length and 5m deep. Under favourable conditions, plants may flower within 6 weeks of germination and the twining nature of the plant can cause serious problems with crops. It is part of the morning-glory family. Seedlings can tolerate frost temperatures of minus 8C. Seeds can remain viable for up to 50 years. A severe infestation of bindweed is capable of producing over 800 kg of seed per acre.

An excellent website to help you identify weeds is: www.omafra.gov.on.ca/english/crops/facts/ontweeds/weedgal.htm