By Judy Hominick,
y the time summer’s finale comes around, many of the lovingly tended garden plants have bloomed their last, and even avid gardeners are ready to throw in the trowel.
Traditionally, this is the time for chrysanthemum blooms whose autumn colors herald fall’s cooler temperatures. Beyond mums, though, there are other great bloomers that save their best for last and not only extend the flowering season but also play an important role for another garden beauty — butterflies.
"Although we see butterflies mostly in the spring and summer, it is important to remember that they still have a very strong need for nectar sources in the fall," says Celia Stuart Whitman, director of the Day Butterfly Center at Callaway Gardens in Georgia. "Monarchs, for example, migrate thousands of miles and need good nectar sources along the way to successfully arrive at their over-wintering site in Mexico."
Keep in mind that even non-migratory butterflies will also need nourishment.
"Other butterfly species that don’t migrate will over-winter in various life stages," says Ms. Whitman. "Some over-winter as eggs and the adults need that extra nutritional boost at the end of the season to lay large numbers of healthy eggs that can withstand the winter. By planting late-blooming species or even a second round of summer nectar species in our gardens, we can provide this boost for these butterflies."
Fittingly, nectar — the sugary liquid inside of flowers — translates into "the drink of the Greek gods," the name given to it by Swedish botanist Carl von Linne (Linnaeus) when he was developing the binomial system for scientifically classifying plants.
While many flowers produce nectar, some do a better job than others at attracting butterflies. Orange, red, purple, yellow and pink flowers readily attract nectar-seeking butterflies, especially short-tubed flowers in a cluster — like verbena or phlox — where it is an easy job to reach the nectar. Gardeners delight in large-size blooms but big is not always better when it comes to butterflies. For instance, the oversized hibiscus flower yields less nectar than the diminutive blossom of the cherry tree.
Equally important when planting for butterflies is the number of plants available. Butterflies prefer a healthy group of one type of flower where they can linger over a meal rather than going from one solitary plant to another scattered throughout the garden.
Fortunately, there are many choices of fall bloomers that will meet the needs of butterflies.
"A lot of butterflies love the eupatoriums and if you put several in your garden, you can have blooms from summer to fall," says Charlene Rowell, native plant horticulturist at the Heard Museum in McKinney. "They are all perennials, need practically no care and are somewhat nondescript until they burst into bloom."
One of the eupatoriums, late-flowering boneset (Eupatorium serotinum), is a prolific fall bloomer that puts on a show for four weeks or more and fairly buzzes with activity as butterflies, bees, wasps and a myriad of other tiny, nectar-seeking insects readily visit the white fuzzy flowers. Numerous ageratum-like flower clusters cover the shrub with clouds of white. The deciduous shrub grows 3 to 5 feet tall and does well in partial shade to full sun with a bit more water in sunnier spots being appreciated.
For many butterflies, particularly the smaller ones, another excellent autumn nectar source is a perennial commonly called frostweed or white crownbeard (Verbesina virginica). Growing from 3 to 7 feet, frostweed blooms from August to November with white terminal clusters. Pruning in early summer will yield shorter plants, if desired. While it is not the showiest flower in the world, the butterflies love it and flock to its sweet-smelling blooms. Choose a sunny to semi-shaded spot for frostweed but be forewarned that it can be invasive as it quickly spreads by runners and seeds. Cutting off spent seed heads will help control frostweed, but give this hardy perennial lots of room to spread.
"Butterflies love the autumn blooming salvias and these bloom until the first hard freeze in late November or early December," says Peter Schaar, Ph.D., a horticultural consultant and designer in Dallas. " Species include Salvia coccinea, S. leucantha, S. x Indigo Spires, S. guaranitica and S. greggii.
Because of the way these flowers are made, Dr. Schaar points out that only butterflies with a long proboscis — like swallowtails and fritillaries — can use these tubular-shaped flowers where the nectar is deep inside the bloom.
Planted in full sun, Dark Night bluebeard (Caryopteris x clandonensis) is a deciduous shrub with rewarding fall clusters of gorgeous, deep blue, nectar-rich flowers set off by silvery green foliage. Growing 3 to 4 feet tall and wide, the shrub is hardy to -20 degrees. Once established, Dark Night is drought tolerant and is visited by numerous bees and butterflies.
A big cluster of tiny flowers atop the succulent leaves of sedums (Sedum spectabile) lures butterflies to sit a spell. Easy to grow, sedums prefer infertile, gravelly soils in a sunny spot with good drainage and are drought tolerant, once established. Many species are available and, depending on where you live, sedums can be annual, evergreen, semi-evergreen or hardy.
Asters (Asters spp), with shades of pink and purple, are a welcome color in the fall landscape and a wonderful plant for butterflies. While they can usually grow to 24 to 30 inches tall, shearing in late May will produce a pleasing compact (12 to 15 inches) mounding plant with loads of daisy-like blooms. Depending on species and location, sun-loving asters can be annuals, perennials or biennials.
Monarch vine or climbing hempweed (Mikania scandens), a twining vine that climbs up to 15 feet looks a lot like boneset with fragrant, fuzzy, ageratum-like white or light pink flowers. Like the boneset, climbing hempweed fairly hums as nectar-seeking insects visit the flowers. Evergreen only in tropical climates, the vine will die down to the ground in the winter but is hardy from Maine to Texas and Florida.
The butterflies, along with hummingbirds, adore Mexican oregano (Poliomintha longiflora) as long as it is blooming, which in Texas is usually to the end of October, says Dr. Schaar.
No matter which fall bloomers are chosen for a garden, most gardeners agree that the sight of a crowd of monarchs hungrily nectaring on a big stand of frostweed is well worth the trouble.
More Late Summer & Fall Blooming Plants
Senna (Cassia corymbosa)
Coral Vine (Antigon leptopus)
Heliopsis (Heliopsis heliantoides)
Maximilian Sunflower (Helianthus maximiliani)
Chives (Allium spp)
Glossy Abelia (Abelia)
Golden-Eye (Viguiera dentate)