A Beginner's Guide To Common Blue Wood Aster

Nothing foretells the coming of Fall as much as when Asters and Goldenrods begin blooming. And in this article I'm going to introduce you one of the more common species, but this one is a bit unique in that it can tolerate dappled shade. Meet Blue Wood or Heart Leaved Aster, a perennial native to much of North America[1]. Scientifically known as Symphyotrichum cordifolium, it blooms hundreds of purple-blue flowers in late summer to early fall. Important to wildlife, it attracts numerous species of bee and butterfly, as well as serving as a host plant for many species of moth and butterfly caterpillars[2][3]. Naturally found in open woods or the forest edges in medium-moist to dry soils, it is one of the rarer asters that can tolerate shade. Now, I'm not saying plant it under a thick canopy of full shade, but it can definitely survive in open forest clearing or along the edge. And this is one of the plants I'm attempting to use to combat Japanese Stiltgrass that is in the forest behind my house. This is a specimen I found hiking in the woods about 10 years ago near the Susquehanna river. But Blue Wood Aster has been a popular choice for landscaping for over one hundred years, as variaties were developed as early as 1910. But as showy and special as this flower is, it can be tricky to keep it upright as it is often prone to arching or leaning over in open settings or fertile soils. Pros and Cons Identification Growing conditions How to grow from seed Wildlife Where to purchase Uses Final thoughts Native Range The primary native range of Blue Wood Aster is from the Midwest to Northeast United States and Canada. But it's range does extend down to southern Mississippi, Alabama, and Georgia. Reference Table Scientific NameSymphyotrichum cordifoliumCommon Name(s)Blue Wood Aster, Heart Leaf AsterNative Range, USDA ZoneCentral and Eastern North America, USDA Hardiness Zones 3-8Bloom TimeLater SummerBloom Duration, Color4-8 weeks, Blue, Purple, WhiteHeight2'-5'Spacing / Spread18-24"Light RequirementsFull sun to part sunSoil TypesSandy loam to clay loam - must drain wellMoistureDry to medium-moistureFauna Associations / Larval HostsAttracts bees and butterflies. Hosts 9 species of moth and several butterflies [IL] Pros and Cons Pros Beauty The numerous flowerheads produced by this plant make it incredibly showy. Depending on conditions and genetics, you may be treated to flowers that can range from purple, blue, to a white-lavender color. But several of these flowers blooming puts on one heck of a show. Wildlife The nectar and pollen produced by this beauty feed and fuel tons of bees and butterflies. This is not to mention all the moth caterpillars it hosts! **Related - Read more about the importance of host plants! Tough This plant is tough in that it can thrive in somewhat drier environments, survive deer and rabbit browsing, and still keep coming back! It is disease resistant and resilient. Cons Flops over One major drawback to this aster is that it is very prone to leaning or flopping (similar to it's cousin, New England Aster). There are several strategies to mitigate this, but it is a problem. Aggressive self-seeding This is probably my only real complaint about this flower. If you don't remove the spent flowerheads, and you have this in a mulched, or somewhat mulched flower bed then you are going to get hundreds of volunteers! So - deadhead this plant if you don't want any self seeding! Identification and Characteristics Stalk The round stalk is light green in Spring changing to a red-brown color by late Summer and becoming somewhat woody. The stalk will branch in the upper portions to terminate into panicles of flowerheads. Leaf Leaves are alternately arranged, up to 5" long by 3" wide, cordate shaped, and medium to dark green. They are attached by narrow petioles that are approximately half the length of the leaf. Margins are serrated, upper surfaces are smooth, while lower surfaces can be glabrous or have hairs along the veins. Flower Upper stems will terminate into panicles of flowerheads. The overall panicle can be 6-18" long, and it will be wider at the based tapering to the tip, so having somewhat of a cone shape. The individual flowerheads are on the smaller side for Asters, and are 1/2" diameter. There will be 10-20 petals (actually ray florets) surrounding disk florets. I love Crab Spiders! This one was happily hunting on this flowerhead, setting up his ambush! Saving seed You can easily save Common Blue Aster seed in Autumn after the flowers are done blooming. Roughly 4 weeks after the flowerheads fade they will change into fluffy seed heads. Simply pluck the seed right off of them, or cut the stalk below the seed heads and place into a paper bag. Shake the bag to release most of the seed. You can store dried seed for a couple years in a cool, dark, dry place. Seed heads of common blue wood aster Root The root system is fibrous and produces short, clump-forming rhizomes. Growing Conditions Blue Wood Aster prefers full to part-sun, and slightly moist to dry conditions. It is drought tolerant, but not overly so. For soil textures, it can tolerate nearly any as long as it drains well. This plant does not like wet feet, and will likely succumb to root rot[2]. How to Grow Blue Wood Aster from Seed Blue Wood Aster needs a cold-moist stratification period of sixty days to get a high germination rate. This can be achieved by either cold-stratifying in the fridge or winter sowing the seed. For planting depth, you don't want to plant the seed deep at all. I usually just scatter the seed on the surface of the soil and press them in to make sure they have good contact. Then simply place the container in a location that gets morning sun and afternoon shade. Make sure you water by misting only, as the small surface-sown seeds can easily wash away. If winter sowing, germination should occur in early Spring once daytime temperatures are in the sixties. Once the plant grows several inches tall or gets 2-3 sets of true leaves, you can separate the seedlings and transfer to larger containers. Or at that point you can plant in it's final location. Just make sure you protect the seedlings with liquid fence. Dividing Blue Aster Like other Asters, Common Blue Aster can be divided in early Spring. I don't recommend dividing in Fall as it can be tricker as the plant may still be putting it's energy into seed production. So, just wait until the plant emerges in Spring. Then use a spade, garden knife or pruning saw to divide the clump into two. You can do this when the clump is about 6-10" across, which usually takes several years. Read more on dividing perennials here. Wildlife, Pests, and Diseases associated with Blue Wood Aster Pollinators The numerous flowerheads produce tons of nectar and pollen that will attract numerous native pollinators including short and long-tongue bees, wasps, flies, butterflies, moths.....And the leaves will host caterpillars of 9 species of moth, along with several butterflies[3][4]. Deer and Rabbits The foliage can be browsed by both deer and rabbits, although it isn't preferred. They mostly will attack it when it is young and the leaves are more tender. Also, young seedlings should always be protected via Liquid Fence or a cage! Disease This plant generally isn't bothered by disease. In extreme drought or too much shade, it can look a little rough though. Where you can buy Blue Wood Aster is not typically sold in nurseries, as it isn't a typical 'garden friendly' plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map. Where to buy seeds We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.) Cultivars of Blue Wood Aster The showiness of this flower has led to the development of several cultivars by the nursery industry (both varieties and hybrids). Many of these were even developed more than a hundred years ago as varieties. Varieties: 'Alderbaran' produces pale lavender flowerheads, and is good at staying erect. The clumps are noted for being compact yet strong. 'Blutenregen' produces lavender flowerheads and is shorter growing only to 36" tall. 'Chieftain' produces lavender-blue flowerheads that are a bit larger diameter. It's noted for staying upright and not arching. 'Elegans' makes flowerheads that are mostly white with a hint of pale purple-violet that can create a silvery effect. It is noted for standing tall. 'Herbstzauber' produces lavender-blue flowerheads. 'Ideal' will make pale-lilac flowerheads with thin petals (ray florets). It flowers earlier in the season. 'Novemberblau' has small blue flowerheads that occur very late in the season, as you can guess from the name. 'Silver Spray' makes pale lavender flowerheads in late summer. The branches are noted for being shorter. 'Sweet Lavender' produces late lavender flowerheads. Hybrids: 'Little Carlow' produces lavender blue flowerheads that are 1" diameter early in the season. This one is noted for standing tall and not leaning so much. 'Little Dorrit' produces large 1" diameter purple-pink flowerheads. The leaves are less heart-shaped and more lanceolate with a dark green color. The drawback to this species is that it can catch powdery mildew easily. 'Photograph' will make pale lavender-blue flowerheads that are a bit smaller at 1/2" diameter. It does produces these quite late in the season. This one is highly prone to leaning or flopping. 'September Mist' makes pale-violet and white flowerheads that are smaller at 1/2" diameter. The branches are sturdy. Uses of Blue Wood Aster Landscaping Using this plant in the landscape can be a bit tricky. It's propensity to flop over can make it challenging to use in formal flowerbeds. But there are several strategies you can try. Heart Leaf Aster leaning First, you can perform the Chelsea Chop in mid Summer. I'm on the border of zone 6/7 and will do this by the 4th of July, cutting the plant back by half. Second, you can plant it near other species that can force it to only grow upwards. So, native grasses and other taller perennials. Third, you can stake or cage it to help it stay vertical. And fourth, you can just let it flop over. Yes, letting it flop over is a strategy if it falls on the ground, as the flowers will still face upwards to an extent. Companion Plants There are numerous plants that make good companions to Blue Wood Aster. Just remember that while Blue Wood Aster can tolerate some shade, not all plants can. That being said, here are some suggestions of plants that grow well with Blue Wood Aster: Aromatic Aster Blunt Mountain Mint Harebell Short's Aster Sweet Goldenrod Also, you should consider adding grasses around it to help force the plant to stay upright. The best choice would likely be Little Bluestem, but any grass can help. A couple other possibilities would be Prairie Dropseed and Side Oats Grama. Dropseed grass Little Bluestem Medicinal Uses There are no noted medical uses of this plant. However the Ojibwa also would burn the root hoping that the smoke would attract animals[5][6]. Conclusion Common Blue Wood Aster is a beautiful native perennial Aster that blooms lavender to blue flowers in late Summer to early Fall. Like other Asters it is very attractive to pollinators and is also a host plant. What makes this one special is that it can tolerate some shade better than most other species of Aster. This contrasts with it's habit of aggressive self seeding and flopping over, which can be unsightly. However, we can easily mitigate those cons via deadheading and performing the Chelsea Chop in early Summer. Find more native plants here