The Asteraceae family, commonly referred to as the daisy or composite family, is one of the largest, with over 32,000 species and 19,000 genera. Importantly, several of its genera play a critical role in our local food webs as top keystone plants, those supporting the greatest number of butterfly and moth caterpillars, and/or pollen specialist bees. This article will focus more narrowly on some late blooming, beautiful garden species which provide critical food resources for our migrating and overwintering wildlife.

Late season and resident insects in our gardens

So, who are these late season visitors and residents in our gardens? Perhaps the best known migrator is the monarch butterfly, famous for its one generation fall flight to its overwintering grounds in Mexico. (The return occurs in stages over several generations.) If, like me, you are fortunate to have monarchs roosting on your property overnight during their fall migration, you can choose to register your site on Journey North, a website to share information about monarch migration. Contributors describe their sites, including details about the plants the butterflies were frequenting.

Another informative site to follow the spring and fall migration is Monarch Watch, where you can register monarch waystation sites – “places that provide resources necessary for monarchs to produce successive generations and sustain their migration”.

Several other butterfly species visit south eastern Ontario for the summer before heading south for the winter. Two frequent visitors are the red admiral (bottom left below), which spends its winter in Texas, and the painted lady (bottom right), which migrates over generations from Canada to Mexico.

Others, very active in the fall, need to build up their food reserves as they overwinter as adults. Both the Mourning Cloak (below left),  and  Milbert’s Tortoiseshell (below right) have two broods, one in late spring or early summer, and a second emerging in mid-August and flying until late October when they shelter for the winter in a state of diapause, in places such as the cavities and bark crevices of trees, and in garages and other outbuildings.

Floral resources in autumn are also critical for our birds and bees. While insect-eating migratory birds pass through our area earlier in the fall when there is ample food available, seed eaters can migrate later and even remain for the winter. Take, for example, the dark-eyed Junco, a sparrow-like ground feeder which breeds in central and northern but overwinters in our area and to the south primarily on a seed diet. Year-round, resident birds such as chickadees, finches, and sparrows rely as well on native forb and grass seeds during winter, when insects are scarce. Later blooming natives like goldenrods and asters are also critical for the specialist bees that require their pollen for their young, and for native bumblebees, as this is the time when drones and new queens mate and forage on flowers. The drones, produced by the old queen from late summer to fall, can often be seen at dawn, having spent the night sleeping in our flowers. 

Recommended late season forbs

The following recommended plant species are rich in food resources for resident and migratory insects and birds. If possible, try a few species within any given genus, as they often have their peak bloom at different times, and therefore better support biodiversity. They are, for the most part, disease and pest free.

During extended periods of drought, native plants (like ornamentals) should be watered, as severe drought decreases nectar quality and quantity and pollen protein quality, and reduces seed set. Extended drought can also alter the phenology of some native plants, delaying the opening of flowers. Water early in the morning and deeply. To increase plant numbers, winter sow the seeds or divide clumps after 3-4 years.

Liatris species – Blazing stars, Gayfeathers

Liatris flowers look quite different from others in this article as they consist of only disc florets. Composite flowers with disc florets exclusively are butterfly and moth magnets, and a welcome addition to any monarch waystation or roosting site. The species with the larger infloresences like L. scariosa are especially good butterfly plants. Liatris spp. are also a good nectar source for native bees and hummingbirds. They grow from a bulb-like corm, making them extremely drought tolerant once established. Be careful to not over-water them. As they bloom from the top down, plants may require staking, especially in richer soils. Below are several species available on the market, all worthy of a place in your garden, blooming from July to October. Plant in full to part sun.

Solidago species – Goldenrods

This genus is second in a list of top keystone perennial plants supporting lepidopterans (104 species of moths and butterflies) and pollen specialist bees (42 species) and as such, should be in every garden. Goldenrods also attract large numbers of a wide variety of pollinators including solitary wasps, flower flies, beetles, butterflies, moths, and native bees including bumble bees. Small birds like sparrows, finches, chickadees, nuthatches, and juncos consume their seeds which are rich in carbohydrates, proteins, and essential fatty acids. Not all goldenrods are aggressive thugs like our native Canada goldenrod. The lovely species below are perfect for the urban garden planted with asters, blazing stars, and native grasses. Most require full to part sun unless otherwise noted.

Solidago nemoralis – Grey goldenrod, Old field goldenrod, 30-75 cm, Aug.-Sept.  native

Solidago rugosa – Rough-stemmed goldenrod, 90-150 cm, Sept.-Oct., native: The cultivar ‘Fireworks’ below has been on the market for over 50 years. On the right, it is planted with New England aster. It forms a bushy clump, easily divided, with arching, unbranched, stems of small yellow flowers.  

Solidago speciosa – Showy goldenrod, 90 cm., Aug.-Oct., native: This species requires less moisture than some others, preferring full sun and, while tolerating a wide variety of soils, prefers a free-draining, sandy soil.

S. bicolor – Silverrod, 30-60 cm, Aug.-Sept., native, below left, and S. ptarmicoides– Upland white goldenrod, 60 cm., Aug-Sept, native, below right. Both have white flowers.

Two native shade goldenrods, below left to right, Solidago flexicaulis – zigzag goldenrod, 45-90 cm, Aug-Sept and S. caesia – blue-stemmed goldenrod, 45-90 cm, Aug-Sept

Finally, Solidago uliginosa– bog goldenrod, 120 cm, Aug-Sept, wetland habitat, host to several insect-induced galls which can provide protein for birds in harsh winters.

Symphyotrichum and Eurybia species – some of our best native Asters

The genus Symphyotrichum is third in the list of top keystone perennial plant genera supporting lepidopterans (100 species) and pollen specialist bees (33 species). It attracts a diversity of pollinators, and its seeds are a favourite of juncos, finches and sparrows. Most prefer full to part sun unless otherwise noted below. Eurybia is the genus of shorter wood aster species- wonderful shade ground covers that support a smaller number of specialist bees, lepidoptera caterpillars and other pollinators. Taller species like S. novae-angliae can be ‘chelsea chopped’ in mid to late June to shorten growth and avoid staking.

Symphyotrichum novae-angliae – New England aster, 90-180 cm, Sept

During drought, this aster’s leaves die back from the base up, so it is advised you plant this behind other mid-size forbs. 

S. shortii – Short’s aster, 90 cm, late Aug- Oct; prefers part to full shade

S. oolemtangiense – sky blue aster, 30-60 cm, Sept – Oct

S. oblongifolium- Aromatic aster, 30-90 cm, late Sept-Oct, non-native, tolerant of drought and poor soils, very late bloomer

Below, left, Eurybia divaricata – White wood aster, 90 cm, Sept-Oct, and below right, Eurybia macrophylla – Big-leaved aster, 30-90 cm, Aug-Sept, both for shade

Symphyotrichum puniceum – swamp aster, 90cm-2 m, Sept-Oct, wet soils

Rudbeckia species

The genus Rudbeckia is fifth in the list of top keystone plant genera supporting pollen specialist bees (29 species), and fourth in perennial plants supporting lepidopterans (20 species of moths and butterflies); its seeds are loved by smaller birds like goldfinches, chickadees, nuthatches, sparrows, cardinals, and juncos. 

Below left, Rudbeckia fulgida (black-eyed Susan, orange coneflower), 60-90 cm, Aug-Oct, and right, R. triloba – brown-eyed Susan, biennial or short-lived perennial, 60-150 cm, both native

Below, R. laciniata – Cut-leaf coneflower, 100-200+ cm., Aug.-Sept., native. This extremely tall coneflower is a knockout that is underused in urban gardens. It’s perfect growing at the back of borders, as a natural screen, or a stand-alone architectural feature.