Asters for Minnesota gardens

Asters are one of our most colorful and reliable late summer and fall flowers. Did you know they are also one of the most critical plants for pollinators?  There are many native bees that are aster specialists — bees that will only feed their young nectar and pollen from asters or a few closely related plants. They are also an important source of nectar for a whole host of other insects including migrating monarch butterflies.

The name aster is derived from the Ancient Greek word for “star.”  A prairie, wetland, woodland or garden studded with asters is surely as stunning as a starry night sky.  What we think of as an individual flower is actually a head comprised of multiple flowers. The central “disk flowers” are arranged in a unique compressed spiral, the number of flowers corresponding to the Fibonacci sequence — or golden ratio — for maximum efficiency. 

The disk flowers are yellow, changing to pink or darker colors when pollinated, while the flowers around the edge are called “ray flowers,” and feature a colorful ray that forms the “petals” of this entire flower cluster.  Picture a daisy — cousin to the aster. When you pull off the petals saying “she loves me, she loves me not,” you are actually pulling off the rays!

There are many local species of asters that thrive in a variety of habitats.  Whatever the conditions in your garden, there is an aster for your landscape (see chart)!  Further research into this group of flowers has led botanists to divide Aster into several genera — with some referring to the “aster disaster” — which includes an array of tough-to-pronounce botanical names including Symphyotrichum, Doellingeria, Eurybia, Canadanthus, Oligoneuron and Ionactis. 

Native asters are the most popular, but garden hybrids — mainly derived from the East Coast species including New York aster (S. novi-belgii) — are becoming more popular to sell along with mums in the fall. Be sure to plant only the single-flowered forms as the full doubles do not provide nectar and pollen for pollinators who rely on aster as a primary food source.

Here's a look at asters suited to a surprising array of different sites, depending on the variety, including asters for sunny, dry sites and rock gardens; asters for wet soils or more common garden soils; and woodland/shade-loving asters.

*Aster codes c= clumping, s=spreading, ss=self sows a lot, flower color

Asters for sunny dry sites and rock gardens

• Aromatic aster (S. oblongifolium) c (also works in garden soils) bluish
• Heath aster (S. ericoides) s (into a tight bunch)  white
• Silky aster (S. sericeum) c, bluish
• Stiff or flax-leaved aster (I. linariifolius) c, bluish
• Upland white aster (O. album) c, white 

Asters for sunny sites, garden soil

• New England aster (S. novae-angliae) c, ss (also good in wet soils) purple, pink (pictured above)
• Sky blue aster (S. oolentangiense) c (also good in dry soils), bluish
• Smooth aster (S. laeve) c, bluish

Asters for wet soil

• Flat-topped aster (D. umbellata) c, white (pictured above)
• Modest aster (C. modestus) c (cold, northeast Minnesota), bluish
• Purple-stemmed aster (S. puniceum) s, bluish

Woodland/shade-loving asters

• Calico aster (S. lateriflorum) c, white
• Crooked aster (S. prenanthoides) c, bluish
• Big-leaved aster (E. macrophylla) s (makes a great groundcover) white (pictured above)
• Blue wood aster (S. cordifolium) c, bluish
• Short’s aster (S. shortii) c, bluish

Asters for Minnesota Gardens