Written by davethetreecenters • September 26 Get to Know the Asters

At this time of year, the well-planned garden gets a big boost, with the arrival of the brilliant, jewel colors of asters blooming in garden beds or natural areas. Few garden visions are as striking as seeing the rich, jewel-tones of purples, blues, reds and pinks glowing among the golds and oranges of fall leaves, as the garden winds down for the year.

The ability of these flowers to bloom in fall is related to the relatively long, warm falls, and Indian summers, that are typical of much of this country. It never developed in the much shorter and wetter falls (autumn) of Europe, so Asters came as a surprise to early explorers and botanists. The arrival of these plants in Europe was greeted with amazement, and they became more popular there than in their native lands. That’s why many of the classic varieties are European, not American, in origin.

It can be confusing, sorting out the different kinds, which vary from low, 1-foot mounds to tall, 5-foot bushes. Even the leaves are very different between them. Then of course, having sorted out fall bloomers, as a new gardener you then come across what seem to be asters, but flowering in summer. . .

So, with plants perhaps blooming in your garden, or at least in your neighborhood right now, it seems like a good time to get to know these plants better.


My older reference books tell me that Aster, as a plant genus, had almost 600 species in it. No wonder that for a long time now, botanists have split it up, based on evolutionary grounds and DNA, creating lots of new names for us to learn, but giving more valuable and useful groupings than one great big pot of ‘aster-soup’. It’s complex, but to keep it simple, the European and Asian asters, which bloom in spring and summer, stay where they were, while the American species have been renamed. From 600, Aster in this modern definition has less than 200 species, while the largest group of American species are now just 90, in Symphyotrichum, with another 30-odd from the Americas in other smaller groups. It’s too bad that they got such a difficult name, as that is sure to slow down the changeover for gardeners. Think ‘symphony orchestra’, and ‘trick’, with an ‘i-o’ between them, to master the new name – there, that wasn’t so bad after all. . .

Fall-blooming Asters

For gardeners, it is Symphyotrichum that is the most important, since all the valuable fall asters have landed in that group. Let’s look at the most important ones, the backbone of fall-blooming asters.

Symphyotrichum novi-belgii: these are the New York Asters. The ‘new Belgium’ in the name was the pre-independence name for much of what is now New York state, and was in fact a Dutch settlement. in England they are called Michaelmas daisies, because they bloom around that time in the Church calendar, September 29. In England and northern Europe this is a popular species, and many of the varieties are British, Dutch or German in origin, because the cooler, damper climate suits this species better than it suits other species, which are more prairie plants, enjoying drier conditions. Low and mounding, with dark-green glossy foliage, these are especially popular and useful for pots, with close to 1,000 varieties, with bright flowers in all shades of purple, violet, blue and pink.

Symphyotrichum dumosum: This plant is commonly called bushy aster, and it’s native to most of North America, growing from Ontario, Canada to Louisiana. Most garden plants are actually hybrids (with the New England aster) and they are best in richer, moist garden soils. They are typically under 3 feet tall, and many are just 18 inches, perfect for edging and pots. You can find wonderful blues, pinks and purples among them, and for gardeners in cooler zones they are hard to beat. Check out ‘Wood’s Blue’ for fabulous sky blue blooms to brighten the grey skies of fall, or the beautiful pink of ‘Wood’s Pink’.

Symphyotrichum novae-angliae: These are the New England aster, and they are easy to identify, because they have hairy leaves that feel rough and dry to the touch, while the others are much smoother and more glossy. As well, although there are smaller varieties, like the wonderful ‘Purple Dome’, which is only 2-feet tall, most are 4 to 5 feet, making larger plants with tall, woody stems topped with big heads of quite large flowers. These are great at the back of beds, tucked between shrubs perhaps, or with other taller perennials – out of the way until they come into their own in early October. These are also plants that are more useful in drier plantings, loving sandy soils, and not so happy in wetter conditions.

Symphyotrichum oblongifolium: rounding out the fall bloomers, and much less well-known, is the aromatic aster. Crush a few leaves and if you smell the warmth of balsam – like the needles of the balsam fir – you know you have this plant. It’s lack of popularity in gardens in mainly because until very recently there really was only the wild plant, with interesting pale violet-blue flowers. It is best-known to wildflower growers, but today we have the variety ‘October Skies’, whose flowers are larger – a full 1½ inches across – and also a near-perfect sky blue. They say October skies are darker than at other times of year, and this plant captures that color perfectly. It is an especially heavy bloomer, with the foliage completely covered with blooms. This is a prairie species, and grows best in drier soils, preferring plenty of sun, and doing best in areas with long, sunny falls.

Summer-flowering Asters

These are much less well-known, and much less seen in gardens, but if you love them in fall, you can also enjoy them in several variations in summer.

Aster alpinus: Yes, there still are some plants that are still ‘aster’, and if you live in a cooler area, and have poorer, drier soil, then you can have Asters in May and June. Called the Alpine Aster, it is native to much of the mountainous areas of Europe, as well as in Alaska and down into Colorado. A popular plants with rock gardeners, (who often prefer to be called ‘alpine gardeners’), this low-grower, no more than a foot tall, is typically violet-blue in bloom, but there are pinks and even whites too. Hardy to zone 5 only.

Stokesia laevis: certainly the most striking of the summer asters, but a little tricky to grow, Stokes’ Aster is wonderful in summer, with incredibly large flowers, 3-inches across, with many petals and striking colors. A popular variety is ‘Peachie’s Pick’, which is a stunning cornflower-blue. To do well with these plants, choose a very well-drained spot, preferably in a sandy or gravel soil, and be prepared to dead-head. You can enjoy these blooms from mid-July to mid-September if you do, so it’s well worth the little effort needed.

Aster x frikartii: a darling of fashionable gardeners, and garden writers, Frikart’s aster is a hybrid, as that ‘x’ tells us. It was created in Switzerland, by crossing Aster amellus with a Himalayan species from India, Aster thomsonii. The most popular variety by far is ‘Mönch’, of a beautiful lavender-blue that goes so well with summer flowers. It is open and branching needing a little attention, but well worth the effort. It will grow in a charming way up between other perennials and shrubs, and get you lots of ‘oohs’ and ‘ahs’ from neighbors and visitors. Take cuttings, rather than trying to divide it, as these will do much better.