To extend the gardening season in Zone 4 and 5 is a goal that most of us share. Our growing season is so short and so lazy about getting started in spring, that fall has become a favored time for many gardeners. The questions that we frequently hear asked refer to which plants - other than the omnipresent mum - can be used to make this happen.
Let's focus on one of the stars, because a spectacular fall garden is easy to accomplish - even in Zone 4!
The huge collection of asters that love our climate makes it easy. For gardeners in the Western mountains or as far north as Houlton (and, of course, all those in the south), asters offer color, fragrance and statuesque form. They even provide cut flowers for the vase.
In Zone 4, these qualities can be hard to find.
The bush-forming native aster flaunts great colors and offers great presence in the sunny garden. We even have two that prefer to grow in the shade. Butterflies find their nectar irresistible. Humans find their beauty irresistible. Plus, humans like the butterflies, too. As they are tolerant of less-than-perfect soil, as well as dry conditions, these are easy plants to grow.
Asters are all easy to manage, as an early season pinch will keep them to the height you would prefer. For the tall varieties, it is possible to pinch (or prune) 6-10” off the top of the plant. This results in a stronger, bushy plant. Possibly, the plant will even send out additional stems. Flowering will not be delayed, if this is done before July 1st. If the plant is too bushy, thin a few stems at this same time, improving the overall appearance and helping to prevent mildew and other foliar diseases. Good air circulation is important, as some asters are vulnerable to mildews. So, give them some space.
Hint: if you decide to let the tall varieties reach full size, cage them with chicken wire. They will remain upright - even if a strong thunderstorm crashes through. We observed this technique while visiting public gardens in Alaska this summer. There, they used chicken wire to help many of the larger perennials: delphinium, eupatorium and heliopsis, for example. And, the best part: the lush foliage of these giant perennials hides the chicken wire. (yes, we poked around until we found it). The garden just looks lush and full.
Not caged.
Thoughtful placement in the garden is important with asters, just in case they are attacked with foliar disease and thus lose lower leaves. Placing a big daylily or ornamental grass in front will go a long way to hide bare legs.
Division of the crowns is the preferred method of propagation. When they get too large, we recommend digging in spring. If you have extra divisions, aster is a good plant to share with friends or the local plant auction, unlike the weedy horrors often passed along at such affairs. These plants will provide reliable fall excitement and brilliant color for years to come.
This season, Plainview Farm is growing 15 different varieties of hardy asters - including two that love the shade. All are native, except for the species tongolensis and tataricus, who come to use courtesy of China and Russia.
These Varieties Thrive in Sunny Areas:
Garden Aster
x-Blue Autumn 30” x 30” Lilac blue flowers begin to flower in late August, continuing well into September. Blue Autumn is perfectly sized for the mid-sized garden. $9.99
Dwarf Aster
dumosus Blue Lagoon 16” x 24” Clear blue flowers begin to bloom in early September and last until October. This is one of the varieties best suited to very small gardens. $9.99
x-Wood’s Blue 12” x 18” Cool blue flowers begin to bloom in early September, bringing nice color to the front-of-the-border. Wood’s Blue is a mildew resistant variety. Also well suited to very small gardens. $8.99
Smooth Aster
laevis Blue Bird 48" x 36” Masses of bright blue flowers with yellow centers begin to bloom in September and continue for many weeks. We have observed this still blooming when the first snow arrives. $9.99
New England Aster
nova-angliae 60” x 48” Violet blue flowers arrive in September atop woody, strong stems that create a large bush. A traditional plant of New England. We recommend giving this plant a hard pinch in June or provide a sturdy cage for it, as it tends to be top-heavy. $9.99
nova-angliae Alma Potschke 60” x 48” Pink flowers explode in September atop strong stems that create a large bush. We recommend giving this plant a hard pinch in June or provide a sturdy cage for it, as it tends to be top-heavy. The color, however, is incomparable and a must-have. $9.99
New York Aster aka Michaelmas Daisy
novi-belgii Brigitte 24" x 30” Pale lavender, semi-double flowers begin to bloom in mid September. This is a shorter and more compact form than other New York asters. $9.99
Aromatic Aster
oblongifolius October Skies 18" x 24” Hundreds of very blue flowers bloom in mid September - exceptionally long-blooming plant with fragrant foliage. $9.99
oblongifolius Raydon’s Favorite 24 - 36" x 30” Hundreds of deep purple flowers bloom in mid September - exceptionally long-blooming plant with fragrant foliage. $9.99
oblongifolius Dream of Beauty 12" x 24” Masses of sugar pink flowers begin in mid September and continue well into November. Native. Drought tolerant and dependable. $9.99
Tatarican Aster
tataricus 25-30" x 36” Lavender blue flowers begin to bloom in early September and continue for weeks. Native to Siberia, China and Korea. $9.99
East Indies Aster
tongolensis Wartburg Star 18" x 12” Lavender flowers begin to bloom in early summer, making this the first aster in your garden. Native of China and the Himalayas. $7.99
Tall Aster
turbinellus 60" x 48” Lavender blue flowers bloom in September. This species is very well branched, making a spectacular specimen. Here the cage will come in very handy. $9.99
These Varieties Thrive in Shady Areas:
Wood Aster
cordifolius 30” x 30” Pale blue flowers in September. This clump-forming, erect species naturalizes well. $8.99
divaricatus 24” x 30” White flowers, set off by arching, dark stems, begin to bloom in late August and continue for many weeks. This clump-forming, erect species naturalizes well. $8.99
Both of the wood aster benefit from a hard pinch in late June or early July, as this helps them maintain a more compact form with less sprawl. We have cut them back to 10” with excellent results. We especially enjoy seeing them rising among the deep green ferns in our woodland garden.