by Silvia Strobl, Master Gardener
It has been a warm start to the fall season, but despite a little more frequent rain in September, the summer drought has continued here north of Peterborough in my 4b Plant Hardiness Zone garden. My soil is also sandy and dry. So what could still be blooming and feeding our most effective pollinators, the native bumble bees?
Although bumble bees are more active in spring and summer, they still need nectar and pollen in fall because the gynes, unmated females that will become next year’s new queen bees if fertilized, are mating and then must build up fat reserves and find a place to overwinter (The Xerces Society 2025). At this time of year you may see bumble bees sleeping on flowers in the morning, especially after a cold night or overnight rainfall. These are mostly the solitary male bumble bees that sleep outdoors. They are searching for a mate, and then they will die. Bad weather may also force female bumble bees to sleep outdoors, but their preference is to return to the hive at night (St. John 2023).
Here are a few drought-hardy native species that were still blooming and supporting pollinators in my garden on October 10th. All are resistant to deer. Sun, soil and moisture requirements, height, bloom colour and bloom time are noted for each.
Smooth Aster (Symphyotrichum laeve)
Full sun – light shade; Sand, loam, clay; Dry to Medium; 4 feet tall; Lavender to light blue; September – October
Smooth Aster has very frost-hardy flowers that often bloom into early November. The lavender to light blue flowers provide a lavish display. It has an upright form, is salt tolerant, and has the ability to survive drought.
New England Aster (Symphyotrichum novae-angliae)
Full sun – Part sun; Sand, loam, clay; Moist-average soil; Tolerates dry soil but may look scraggly; 2-5 feet tall; Purple, pink; August – October
New England Aster is another late bloomer, often lasting until it is hit by a few hard frosts (Booth nd). It is a clumping perennial that can be divided every 3-5 years and also “politely” seeds into garden gaps. To keep it from flopping over in fertile soils, it can be “Chelsea-chopped” in mid-June to restrict its height. It is an important nectar plant for migrating Monarch butterflies, as well as a larval host for 5 butterflies and more than 40 moth species (Booth and Gray 2024).
Zig Zag Goldenrod (Solidago flexicaulis)
Part shade to Full Shade; Prefers, fertile loam but tolerates heavy clay; Well-drained soils; 1-3 feet tall; Yellow; August – October
Zig Zag Goldenrod is a non-aggressive goldenrod that is a great addition to the shade garden. It provides pollen and nectar for both short- and long-tongued bees, wasps, flies and butterflies and it is the larval host plant for over 45 species of moths (Booth and Gray 2024).
Blue-stemmed Goldenrod (Solidago caesia)
Part shade to Full Sun; Most well-drained soils, tolerates poor soil; 1.5 – 3 feet tall; Yellow; August – October
Blue-stemmed goldenrod has yellow clusters of flowers that bloom all along the purplish-blue stem in early autumn, creating streaks of gold if planted in large patches. Unlike other goldenrods, it does not spread aggressively. Its leaves host larvae of 45 moth species (Gray and Booth 2024).
Button Blazing Star (Liatris aspera)
Full Sun; Dry-Medium; Sand, loam; 2 – 5 feet tall; Yellow; August – October; Purple-Pink
Button Blazing Star is one of the most drought tolerant blazing stars. Unlike Dense Blazing Star (Liatris spicata) its flowers are held on individual stems rather than in spikes and the corms cannot be divided. Birds especially prefer its seeds (Diboll and Cox 2023).
The evening of October 9th we had a second hard frost (-6oC with wind chill) but the next day all of these native perennials were still blooming. If you are looking at your garden this Thanksgiving and not seeing any plants still flowering and supporting pollinators, maybe make plans to add one or two of these next spring?
REFERENCES
Booth, S. no date. Native Asters for Ontario Gardens.
Diboll, N. & H. Cox. 2023. The Gardener’s Guide to Prairie Plants. The University of Chicago Press. 636 pp.
Gray, R. and S. Booth. 2024. The Gardener’s Guide to Native Plants of the Southern Great Lakes Region. Firefly Books. 352 pp.
St. John, K. 2023. A Closer Look at Sleeping Bumblebees. Outside my Window blog post.
The Xerces Society. 2025. Bumble Bees: Nesting and Overwintering.
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