Scott Woodbury did a recent program where he talked about asters and goldenrod and gave advice on both.
Here is some of the advice he gave plus my experiences with specific species.
Spring Haircut – (SH) he talks about cutting back most of the asters and goldenrod by 50% – 70% in late April or early May. He does this once. I also do this with ironweed and I’m trying this on some of my echinacea to encourage some late blooms.
Asters in general are clump forming except for Willow-Leaf Aster.
Aromatic Aster – Symphyotrichum oblongifolium – Try dividing this in spring. Easy to grow from seed after stratification. Take cuttings in June.
Blooms in October/November. Mounds with lots of flowers. Good for pollinators late in the year. Makes a nice hedge.
Calico Aster – Symphyotrichum lateriflorum
2′ height – can be weedy.
Drummond Aster – Symphyotrichum drummondii
This is shade tolerant woodland aster. Short-Lived.
Hairy Aster – Symphyotrichum pilosum
Lots of seeds and weedy.
Heath Aster – Symphyotrichum ericoides – SH – Try this.
Can grow tall and flop over. Don’t use.
New England Aster – Symphyotrichum novae-angliae – SH
I’ve found this to be an aggressive grower that usually flops over and I usually end up staking it. It will tolerate some shade. It’s a butterfly magnet. It blooms around the time that Monarchs show up in St. Louis. Purple Dome is a cultivar that is supposed to stay small, but mine has always gotten large. Seeds can be a problem.
Purple Aster – Symphyotrichum patens (Called Spreading Aster) – Try This
Showy – Flowers Aug, – Oct. Tolerates some shade.
Sky Blue Aster – Symphyotrichum oolentangiense
Lots of seeds.
Willowleaf Aster – Symphyotrichum praealtum
Aggressive with underground runners. Not appropriate for most gardens.
Goldenrods
Atlantic Goldenrod – Solidago
Scott likes this, but may not be available.
Blue-Stem Goldenrod – Solidago
Long stems which arch down. Good for woodland.
Buckley’s Goldenrod – Solidago buckleyi –
Grows in the woods. 2′ – nice shape, but reseeds easily.
Cliff Goldenrod – Solidago drummondii
Would cascade over a retaining wall. 24″ – nice plant – Sun and Part Shade.
Golden Fleece – Solidago sphacelata – I grow this.
It stays low and spreads out. 24″ tall.
Riddell’s Goldenrod – Solidago riddellii
Rain garden – 3′ tall –
Rough-Leafed Goldenrod – Solidago rugosa
Likes shade. Grows in woods. Showy.
Showy Goldenrod – Solidago speciosa – SH
Spear shaped – upright
Stiff Goldenrod – Solidago rigida – SH
Aggressive seeder. Pollinators like this in my garden. Need to deadhead in the home garden.
Tall Goldenrod – Solidago altimissa – SH
Don’t plant this. It spreads by rhizomes and will take over a garden. It make take years to pull it all out.
Zig Zag Goldenrod – Solidago flexicaulis
Can be clump forming or slightly spreading. Shade tolerant. I took mine out as there were no pollinators on it.
Cut stems 12″ to 18″ high and leave for solitary bees.
Prairies can have 46 species in a 20″ x 20″ area. That’s why the plants are not as tall and vigorous in a prairie.
Butterfly Gardening 