Planting Asters

Symphyotrichum sericeum

Symphyotrichum undulatus

Symphyotrichum pilosa

I came to asters fairly recently. I'll admit that. In my earlier days, I saw them as mostly mundane. They seemed common and not at all that showy. I fell in love much earlier with other members of the aster family - blazing stars (Liatris spp.), rosinweeds (Silphium spp.) and the like. Where and when I changed my mind is still a mystery for me, but I did and since then I've been slowly accumulating as many of the Symphyotrichum species I can lay my hands on. 
Asters in the genus Symphyotrichum seemingly have not been the target of most of the native plant nurseries here in Florida either. That's not true in other parts of the country. If you go online and look at what's offered in the Northeast, Midwest and West, you'll find a good selection of native species, but here in Florida, the vast majority of our 28 native species have never been offered or, if so, are propagated by just a very few and then, only sporadically. Seemingly, there's no market for most. The few exceptions are Carolina climbing aster (S. carolinianum) which is actually now considered by most taxonomists to be in a separate genus, and ricebutton aster (S. dumosus) which is likely really several species that have been lumped together. While Carolina aster is beautiful, it really only grows well in extremely wet soil, in areas that may be inundated during the summer rainy season. All of the forms of ricebutton aster I have seen offered have been of the type that suckers profusely and does so by sending up a single stalk here and there. It is not a "full" plant vegetatively and to me, it leaves something to be desired in a wildflower planting of mixed species. That leaves 26 species that are never, or very rarely, available to home gardeners such as myself.
Over the past few years, I have made it a point to search these out with the idea of adding them to my landscape and then to propagating them in my hobby nursery that I call Hawthorn Hill. For some, I have had friends donate a few seeds or a plant and for others, I have chanced upon plants in my travels that were in seed. Slowly, but surely, I have acquired more than a dozen that now reside somewhere in my landscape. 
There are a few that I will not add here. A few, like Bahama aster (S. bahamense) are not very showy and require soils that few can adequately provide in a typical landscape setting. There are a few that occur only in saltmarshes - which I can't replicate. A few others are simply too aggressive for my landscape. I truly love Elliott's aster (S. elliottii), for example, but it completely takes over whatever area it is planted in once it takes hold. Elliott's aster needs moist to wet soils, and in these conditions it will produce hundreds of stems within a year or two, and as it stands 6-8 feet tall, there is nothing that can quite compete with it. I've planted it in a wetland wildflower area near me and it fits that lake-shore area perfectly. In the fall, the large stand of bright and fragrant lavender flowers is spectacular. I tried it years before in a small wetland I created at my former home and I soon had to weed it out completely; a testament to the concept of right plant, right place.
That still leaves about 20 species that have landscape potential in my mind. Asters, by their nature, are excellent plants for pollinators. That's true for all members of the family Asteraceae of course. Because they produce dozens to many hundreds of simple tubular flowers in a head, a pollinator such as a butterfly or bee can visit each without hardly having to move. Such economy of movement is a godsend to them as it conserves the energy they have to expend in gathering sustenance and it reduces their movement and exposure to predators. It's the inner circle of real flowers, inside an array of showy petals that draws them in and it's the inner circle that produces flowers in a procession of outside to inside the circle that provides nectar and pollen for weeks before each head is finished. 
Asters in the Symphyotrichum family serve as host plants for the pearl crescent butterfly - and perhaps others. I have not seen any real data on whether all of them provide this service or whether it is confined to just a few, but it seems worth giving them all a chance. 
Asters can have some drawbacks. Although I have never had one colonize my gardens by seed like I have with goldenrods (Solidago spp.), they do put out rhizomes when they are well established and grow outwards into a mass. A few, like Elliott's do so very aggressively, but most are really quite well behaved. In my landscape here, I welcome it, and what this translates to is that you often need to plant only a few to eventually get a patch.
I have run out of room in my front-yard wildflower planting for all of the species I wish to add, so I have created an outer planting area along the south edge of my deciduous woodland planting in the backyard. In the front, I have added a great many species - silver (S. concolor), Walter's (S. walteri), Georgia (S. georgianum), late purple (S. patens), skyblue (S. oolentangiense), scaleleaf (S. adnatum), and a form of ricebutton aster that forms a low mound of foliage instead of a single wand. I have a Carolina aster in a large pot without a drainage hole. It sits under a point of my roofline where water pours off during a rain. It is growing by leaps and bounds in this setting and it has the space it needs there to ramble. At this time, it would seem that all of them are doing well there. There's just no space left for others as the plants and all of the others I added last year have expanded and filled in the growing space.
My new planting area is on the south side of my woody plants and because of that it should receive the ample sunshine that most asters seem to require. A few days ago, I planted three of the "new" species I've been keeping here in pots - western silver (S. seriaceum), wavyleaf (S. undulatum), and white oldfield (S. pilosa). I know that the white oldfield will spread over a substantial area if it does well here, so I've given it a place where it can fill in a relatively large area. It will be stopped by the shade of my trees to the north and I may have to weed it a bit elsewhere. It's a challenge I've accepted up front. Before you plant anything, it is important to know its habits as well as its growing requirements.
I've got a few more growing here that I hope to add before I'm finished. I recently potted up a number of Short's aster (S. shortii) from a flat to individual pots and I'll be adding some of these about a month from now if all goes well. Once I've done that, I'll have exhausted all of the species I've been able to locate up to now. I'm still on the lookout for others, but that's what makes life interesting... I once had Chapman's aster (S. chapmanii), but could not keep it moist enough in my former landscape. It's a beautiful wildflower that I'd like to try here in my new one. Recently, a good friend shared some seeds of another aster relative with me that I also "lost" years ago -  coyote thistle aster (Eurybia eryngifolia). These are tiny right now, but I'm hoping that a couple of them will reach the stage where I can plant them out and give them another try.
I firmly believe in the concept of planting diversity. In this case, I may have gone a bit overboard in some people's minds, but it is only mine that I have to consider. My landscape is an experiment, it is a source of plants for other like-minded folks, and it is a never-ending source of enjoyment for me. It also has become a life raft for an ever-increasing number of pollinators.