It’s fall, the time for Goldenrods and Asters. For this month’s Plant of the Month, I will be covering Smooth Aster – a beautiful purply-blue, prolifically blossoming fall staple in the garden. One of the earlier asters to bloom in my garden, it signals the coming of autumn with its cooler temperatures and fall colours. As usual, the Plant Description and In the Garden sections are courtesy of Shaun Booth from In Our Nature. 

Common Name: Smooth Aster 

Scientific Name: Symphyotrichum laeve 

Family: Asteraceae (Aster Family) 

Alternate Common Names: Glaucous Aster, Purple Aster, Smooth Blue American Aster, Smooth Blue Aster, Smooth-leaved Aster 

Plant Description: Smooth Aster features one to a few erect, hairless stems that are usually green but can be a reddish colour. Leaves clasp the stems in an alternate pattern and measure about 10 cm long and 4 cm wide. They are smooth (almost waxy), shiny, toothless, and greenish blue on top and light green underneath. The basal leaves are toothed with winged petioles and are oblanceolate. Open, branching flower clusters are found at the top of the plant. Flowers can also arise from upper leaf axils (where the leaves meet the stem). Individual flowers measure up to 2.5 cm across and feature 15 to 30 oblong ray florets (petals) surrounding yellow centres that turn purplish red with age. Petal colour can vary from light blue to light purple. Four to six layers of bracts surround the base of each flower. They are smooth, appressed (flattened), and light green to bluish green and have diamond-shaped ends with a dark tip. Flowers give way to dry, brown, narrowly cone-shaped seeds, each with a tuft of light brown hairs that allow them to be carried by the wind. 

In the Garden: Smooth Aster is valued by gardeners for its copious blue blooms and non-aggressive growth habit. The flowers are frost hardy and bloom late into fall while the tough stems will persist through the winter months. Smooth Aster is easy to grow but doesn’t like being shaded by taller plants. A favourite food of rabbits, possibly due to the smooth leaves. 

Skill Level: Beginner 

Lifespan: Perennial 

Exposure: Full sun 

Soil Type: Any well-drained soil 

Moisture: Dry 

Height: 20–70 cm (occasionally to 120 cm) 

Spread: 30–60 cm 

Bloom Period: Sep, Oct (to frost) 

Colour: Blue 

Fragrant (Y/N): N 

Showy Fruit (Y/N): N 

Cut Flower (Y/N): Y 

Pests: No serious insect or disease problems, though powdery mildew can affect the plant in some years 

Natural Habitat: Fields, open woods, and roadsides 

Wildlife Value: The nectar and pollen of the flower heads attract many species of native bees, butterflies, and other insects and Ruffed Grouse (Bonasa umbellus) and Wild Turkey (Meleagris gallopavo) feed on both the leaves and seeds of asters; the seeds are also eaten by mice and American Tree Sparrows (Spizelloides arborea) 

Butterfly Larva Host Plant For: Silvery Checkerspot (Chlosyne nycteis), Tawny Crescent (Phyciodes batesii), Northern Crescent (Phyciodes cocyta), Pearl Crescent (Phyciodes tharos), Painted Lady (Vanessa cardui) 

Moth Larva Host Plant For: At least 40 species of moths, including members of the tiger moths, ribbed cocoon-maker moths, case-bearer moths, twirler moths, geometer moths, leaf-blotch miner moths, slug caterpillar moths, owlet moths, clearwing moths, flower moths, trumpet leafminer moths, and tortrix moths. 

USDA Hardiness Zones: 3–9 

Propagation: Direct sow the seeds in late fall or early spring. No pretreatment is necessary even when starting indoors, but seeds need light to germinate. Germination is said to be slow. Transplanted seedlings will likely bloom in their first year. You can also multiply plants from root cuttings. 

Additional Info: Symphyotrichum laeve will tolerate short durations of seasonal flooding. It also self-sows strongly in open areas that are burned and mowed and is walnut (juglone) tolerant. 

Native Range: 

Some of the most popular posts on my Facebook page are the images of my Canada Lily (Lilium canadense). Technically not native to the part of Ontario that I live in (it could be classified as a “near native” here), it nevertheless thrives in my garden. Each year this plant sends up more shoots and has more blossoms.  

I planted it as a small potted plant five years ago. A year later it was about 4’ tall and had two blossoms. The next year it shot up to just over 7’4” and had 24 blooms. Last year a second stalk appeared and the taller one reached an amazing 7’9” and there were 53 blooms between the two plants. This year, it just got bigger and more spectacular. A total of 8 stems produced 102 flowers and the tallest of these plants reached an incredible 7’11.5”. 

In this month’s Plant of the Month I am writing about this amazing species.  As usual, the Plant Description and In the Garden sections are courtesy of Shaun Booth from In Our Nature. 

Common Name: Canada Lily 

Scientific Name: Lilium canadense 

Family: Liliaceae (Lily Family) 

Alternate Common Names: Meadow Lily, Wild Yellow Lily, Yellow Wood Lily 

Plant Description: Canada Lily features smooth, light green stems that are unbranched, except at the top where the flowers are found. Leaves are distributed along the stem in whorls of three to eight with some smaller alternate leaves occurring along the upper portion of the stem. Each leaf is up to 15 cm long, 2.5 cm wide, smooth, toothless, and narrowly ovate. Stems terminate with up to 20 nodding, trumpet-shaped flowers borne on long stalks and can range in colour from reddish orange to yellow. These flowers are up to 10 cm across and feature six tepals that flare backwards (but not past the base of the flower), six stamens, and dark dots on the inside of the tepals. Flowers become oblong, 5 cm long seed capsules that are divided into three cells containing flat seeds. 

In the Garden: Canada Lily adorns the summer garden with trumpet-like flowers that hang gracefully from the plant. Besides its blooms, it is valued for its clumping habit and interesting whorled foliage. 

Skill Level: Beginner to intermediate 

Lifespan: Perennial 

Exposure: Full sun to part shade (prefers dappled shade) 

Soil Type: Rich loamy or slightly sandy soil 

Moisture: Moist to medium 

Height: 90–240 cm 

Spread: 15–20 cm 

Bloom Period: Jun, Jul, Aug 

Colour: Red, orange, or yellow 

Fragrant (Y/N): Y 

Showy Fruit (Y/N): N 

Cut Flower (Y/N): Y 

Pests: The caterpillars of several moth species feed on the leaves, stems, and corms of Canada Lily, and the introduced Lily Leaf Beetle or Red Lily Beetle (Lilioceris lilii) feeds on its leaves 

Natural Habitat: Wet meadows, moist rich woods, streamsides, and wetlands, and along wet roadsides and railroads 

Wildlife Value: The nectar attracts large butterflies, particularly the Great Spangled Fritillary (Speyeria cybele) and various swallowtail butterflies. Some bees collect pollen from the flowers, but they are ineffective at cross-pollination because of their small size. A number of mammalian herbivores browse on the foliage, and voles and chipmunks are known to eat the corms. Rabbits ate off several new lilies I planted last year, and squirrels dug out the corms of others before I had a chance to cover them with chicken wire – but once established the plants seem pretty robust. 

Butterfly Larva Host Plant For: None 

Moth Larva Host Plant For: Carrion Flower Moth (Acrolepiopsis incertella), Burdock Borer Moth (Papaipema cataphracta), Golden Borer Moth (Papaipema cerina), Common Borer Moth (Papaipema nebris), Sparganothis Leafroller Moth (Sparganothis sulfureana) 

USDA Hardiness Zones: 4–8 

Propagation: [WC; D] Canada Lily seeds must undergo a period of one to two months of warmth, at which time they will swell and become a small bulb. These then need another 60 to 90 days of cold before they begin to sprout. Seedlings typically go dormant by midsummer. Plants grown from seed will take five to six years before they flower. Propagation is easiest from division of the scaly bulb, which can be dug as soon as the plant goes dormant in late summer. 

Additional Info: Canada Lily is primarily pollinated by the Ruby-throated Hummingbird (Archilochus colubris) and large butteflies such as the swallowtails. Canada lily is listed as Threatened in Indiana. 

Native Range (shaded area on map): 

Areas with a fair bit of moisture are perfect candidates for this beautiful annual flower, often found along shady stream banks and in low forested wetland areas. Long known for the ability of its crushed stems to cure the itch of mosquito bites or even poison ivy, its exploding seed pods are also a favourite of children of all ages. Plant Description and In the Garden sections, below, are courtesy of Shaun Booth of In Our Nature. 

Common Name: Spotted Jewelweed

Scientific Name: Impatiens capensis 

Family: Balsaminaceae (Touch-me-not Family) 

Alternate Common Names: Orange Balsam, Orange Jewelweed, Spotted Touch-me-not, Wild Balsam 

Plant description: Jewelweed is a heavily branched plant with smooth, succulent stems that are reddish green and nearly translucent. Oval to egg-shaped leaves are borne in an alternate pattern and measure up to 7.6cm long and almost 3.8cm wide. They are smooth to the touch with widely spaced, broad teeth. Flowers measure 2.5cm long by 2cm wide and emerge from upper leaf axils (where the leaf meets the stem) in small clusters of 1-3 flowers. Each flower is tubular in shape with two broad lower lobes and one smaller upper lobe. Sticking out from the back of each flower is a long, narrow nectar spur that curls back underneath of the flower. Colour can vary but they are usually orange with red spots on the front petals. Note that these red spots may be very dense or even completely absent, depending on the specimen. Flowers give way to thin green seed pods that pop open from the slightest touch to spread their seeds away from the mother plant. 

In the Garden: The vibrant orange flowers of Jewelweed dangle gracefully between its lush foliage, blooming for months on end. It will eagerly self-seed and quickly cover shady, moist areas with beauty and wildlife value. 

Lifespan: annual 

Exposure: shade to part shade 

Soil Type: fertile clay, loam, sand with an abundance of organic material 

Moisture: moist, wet (submergence of the roots by flood water is tolerated for up to 2 weeks without apparent ill-effects) 

Height: 90-150 cm 

Spread: 45-75 cm 

Bloom Period: Jun, Jul, Aug, Sep, Oct (till frost) 

Colour: orange 

Fragrant (Y/N): N 

Showy Fruit (Y/N): N 

Cut Flower (Y/N): Y 

Pests: few pest problems 

Natural Habitat: shady wetlands 

Wildlife value: Hummingbirds and butterflies seek nectar, and several native bees (listed by the Xerces society as of special value to bumblebees) collect pollen; deer will browse the foliage, while mice and many birds eat the seeds 

Butterfly Larva Host Plant For: none 

Moth Larva Host Plant For: Obtuse Euchlaena (Euchlaena obtusaria), Pink-Legged Tiger Moth (Spilosoma latipennis), White-Striped Black (Trichodezia albovittata) 

USDA Hardiness Zone: 2-11 

Propagation: [CWC, L, M] Seeds are best sown when fresh as they do not tolerate drying out. Jewelweed seeds need light to germinate and a period of cold moist stratification, followed by warm moist period, then another period of moist cold. They typically require 2 years to germinate in the wild, though depending on the winter conditions they may germinate after the first winter. 

Additional Info: The juice from jewelweed stems contains a compound called lawsone which has shown to have antihistamine and anti-inflammatory properties. It is said to relieve itching from poison ivy mosquito bites, stinging nettle and has also been used to treat athlete’s foot. 

The plant gets one of its common names, ‘touch-me-not’ because when the ripe seed pods are touched even lightly, the pods’ explosive spring-action projects the seeds for a distance of a meter or more. 

From my YouTube videos – this is a jewelweed seed pod “exploding” recorded at 1/8 normal speed. It’s no wonder their seeds find their way far from the parent plant.

Native Range: 

Very similar to Yellow Jewelweed: 

Scientific Name: Impatiens pallida 

Common Name: Yellow Jewelweed 

Alternate Common Names: Balsam-weed, Pale Jewelweed, Pale Snapweed, Pale Touch-me-not, Quick-in-the-hand, Silverweed, Slippers, Slipperweed, Snapweed, Speckled Jewels, Spotted Touch-me-not, Wild Balsam 

Yellow Jewelweed has fewer, but larger, yellow flowers than Spotted Jewelweed, with a shorter spur that bends down rather than parallel with the flower. It also has more finely toothed leaves and is a much larger plant overall. I. pallida also seems to prefer soils on the sandier end of the spectrum vs I. capensis, which seems to favour heavier soils. 

USDA Hardiness Zone: 3-7 

Native Range: 

Monarda punctata – where have you been all my life?! About 3 years ago I bought a small plug of spotted beebalm on a whim while visiting a native plant nursery. Little did I realize that this would soon rank in my top 10 favourite plants (and with over 300 species in my yard – that’s saying something). If you give it a sunny spot with well-drained sandy soil and minimal competition, it will reward you with a show of beautiful pink bracts, spotted creamy-green flowers, and lots and lots of pollinators. It self-seeds in my garden and my single plants has grown to a patch about 3’ across. The seedlings are easy to dig up and relocate so I have since added more in other locations around my yard. The Plant Description and In the Garden sections, below, provided by Shaun Booth of In Our Nature. 

Common Name: Spotted Beebalm 

Scientific Name: Monarda punctata 

Family: Lamiaceae (Mint Family) 

Alternate Common Names: Bee Balm Horsemint, Dotted Horsemint, Dotted Mint, Horsemint 

Plant description: The stems of Spotted Beebalm are brown to reddish purple, 4-angled and densely hairy. Leaves are softly hairy and found in an opposite arrangement, measuring up to 7.5cm long and 1.2cm wide. You will notice that smaller leaves emerge from leaf axils (where leaves meet the stem). Lower leaves are serrated while upper leaves may have smooth margins. Tubular flowers are found in whorls around the upper leaf axils with one cluster being found at the very top of each stem. Each flower is 2.5cm long and yellow with purple spots. The upper lip of each flower is long, narrow and arching while the lower lip is 3 lobed. Each flower cluster is backed by 5-10 leaf-like bracts with pink, lavender or white upper surfaces. Note that some leaves can take on the colour of the bracts. Flowers turn into seed heads containing small, dry, oval seeds. 

In the Garden: The quirky beauty of Spotted Beebalm is sure to turn heads in your garden! It is one of the most drought tolerant of the Monarda species and certainly the most unique. Its foliage has a wonderful minty aroma and, despite being in the mint family, it retains a clumping habit. Herbivores rarely bother with this plant. 

Lifespan: annual, biennial or short-lived perennial  

Exposure: full sun to part sun 

Soil Type: sandy soil – requires excellent drainage 

Moisture: dry 

Height: 15-60 cm (occasionally to 90 cm) 

Spread: 30 cm 

Bloom Period: Jul, Aug, Sep 

Colour: yellow with maroon markings, however the bracts are showier and may be purple, pink, white or yellow 

Fragrant (Y/N): Y (foliage) 

Showy Fruit (Y/N): N 

Cut Flower (Y/N): Y 

Pests: susceptible to powdery mildew, though because this plant prefers drier conditions than its cousins, M. didyma and M. fistulosa, it tends to be affected less often than the other two 

Natural Habitat: sandy prairies and savannas, sand dunes around the Great Lakes and sandy fields with little grassy competition 

Wildlife value: Butterflies (it is a favourite of the endangered Karner blue), skippers, hummingbird moths, hummingbirds, honeybees, bumblebees and other native bees sip nectar from the flowers. In my garden, if you want to see a Great Black Digger Wasp (Sphex pensylvanicus) just stand by the M. punctata for a few moments when it is blooming – they are almost always on the plant. The strongly scented leaves and stems are usually avoided by mammalian herbivores. 

Butterfly Larva Host Plant For: none 

Moth Larva Host Plant For: Orange Mint Moth (Pyrausta orphisalis), Raspberry Pyrausta Moth (Pyrausta signatalis), and Gray Marvel (Anterastria teratophora) 

USDA Hardiness Zone: 3-9 

Propagation: No treatment needed, though if holding for spring sowing, the seeds should be stored in a cool and dry environment. Seeds need light to germinate, so sow on the surface. It can also be propagated by 2-3-node cuttings of young plants. Because they are such a short-lived perennial, root division is usually not worth the effort. 

Additional Info: does not tolerate grassy competition 

Native Range:

In the short (5 second) video below, you can watch the unique relationship between plant and insect. As the wasp moves from flower to flower, it’s back is dabbed with pollen, which it then spreads to the next flower.

This month’s plant is a member of the Allium family noted for its beautiful clusters of pink flowers in mid to late summer that attracts pollinators from far and wide. As a member of the onion family, the tender young stems can be used where you would use chives and the bulbs can be used raw or cooked – though they have a very strong flavour.  The Plant Description and In the Garden sections, below, provided by Shaun Booth of In Our Nature. 

Common Name: Nodding Wild Onion 

Scientific Name: Allium cernuum 

Family: Liliaceae (lily family) 

Alternate Common Names: Lady’s Leek, Nodding Pink Onion 

Plant description: Nodding Onion features a tuft of basal leaves originating from a bulb. It’s arching, grass-like leaves reach up to 30cm long and 1cm wide. The leafless flower stalks rise slightly above the foliage and bend downwards at the top, producing a nodding umbel of flowers (hence the name “Nodding” Onion). All parts have a strong onion smell. 

In the Garden: Nodding onion is a small but showy plant that thrives in tough sites. For best effect, plant it in large groupings. It doesn’t like competition from taller plants so plant accordingly. This is a very well-behaved, clumping plant but may self-seed in optimal conditions. 

Lifespan: perennial 

Exposure: part shade to full sun 

Soil Type: humus-rich, neutral to alkaline soils but will adapt to acidity, sand to clay 

Moisture: medium dry to moist 

Height: 40 cm 

Spread: 8-15 cm 

Bloom Period: Jun, Jul, Aug 

Colour: pink (white) to light lavender 

Fragrant: (Y/N): Y (leaves produce an onion-like scent when crushed) 

Showy Fruit (Y/N): N 

Cut Flower (Y/N): N 

Pests: no serious insect or disease problems 

Natural Habitat: prairies, rocky outcrops and at the edge of dry open woodlands 

Wildlife Value: supports a variety of generalist pollinators including native bees and the nectar attracts hummingbirds and butterflies 

Butterfly Larva Host Plant For: Hairstreak butterflies (Satyrium spp.) 

USDA Hardiness Zone: 3-8 

Propagation: Spreads by seed and bulb offshoots. Sow seeds in the fall or provide 60 days moist, cold stratification if spring planting. Cover lightly with soil/growing medium. Plants benefit from being divided every third year or when 8-10 bulbs appear in the clump. Plants may be divided any time of the year. 

Additional Info: Walnut (juglone) tolerant. Nodding Wild Onion is rare in Ontario – it is believed that the only natural populations left are those growing in alvar habitat on Pelee Island. In New York it is classified as Threatened.