UT Gardens’ October 2022 Plant of the Month

Submitted by Whitney Hale, Education Coordinator, UT Gardens, Knoxville

Did you know that the aster family gets its name from the Greek word for star? Since I am in the Tri-Star state, I have chosen three native Tennessee asters as the focus of this column. ‘Rockcastle aster’ (Eurybia saxicastellii), ‘Raydon’s Favorite’ (Symphyotrichum oblongifolium ‘Raydon’s Favorite’) and ‘Rachel Jackson’ (Symphyotrichum oblongifolius ‘Rachel Jackson’) are attractive southeastern natives that provide three seasons of interest while supporting wildlife and showcasing what Tennessee stars offer in the landscape.

Our first Tennessee star is the white ‘Rockcastle aster’ that is native only to Tennessee and Kentucky. This is one of the most visited-by-pollinators plants in East Tennessee according to the latest research at the University of Tennessee. The two other native Tennessee stars cited here are more commonly found. Believed to have originated near Lookout Mountain in southeast Tennessee, ‘Raydon’s Favorite’ is an excellent aromatic aster to add to the garden. It is similar to the standard garden favorite ‘October Skies’ but has a more compact growth habit and a darker purple color. ‘Rachel Jackson’, found in former First Lady Rachel Jackson’s garden at historic Hermitage mansion in Nashville, has purple flowers that stop you in your tracks when seen en masse. Plant either of the latter varieties in front of a living screen or in a pocket area of the garden that can be viewed from various angles. I love the purple against a contrasting backdrop. While ‘Rockcastle aster’ blooms from August to November, both ‘Raydon’s Favorite’ and ‘Rachel Jackson’ bloom October to November.

Each of these asters adds winter interest to the garden when the stems are left uncut and also provides excellent shelter for our native pollinators. Cut stems back in early spring for lush growth. All three asters grow well in average garden soil and can be found at UT Gardens, Knoxville. ‘Rachel Jackson’ is on display near the Gardens’ Neyland Greenway. ‘Raydon’s Favorite’ grows near the Kitchen Garden and ‘Rockcastle aster’ in research sites throughout the Gardens. While ‘Rockcastle aster’ can tolerate partial shade, the other two prefer full sun. ‘Rachel Jackson’ is hardy to USDA zone 4, ‘Raydon’s Favorite’ is hardy to zone 3 and ‘Rockcastle aster’ is hardy to Zone 6a- making them ideal perennials to add to your Tennessee home landscape. Plant these asters in a place where you can enjoy their beauty up close and from afar to take advantage of their propensity to attract pollinators and their delightful colors. I encourage you to show your state pride by planting and preserving these three Tennessee stars.

The UT Gardens includes plant collections located in Knoxville, Crossville and Jackson. Designated as the official botanical garden for the State of Tennessee, the collections are part of the UT Institute of Agriculture. The Gardens’ mission is to foster appreciation, education and stewardship of plants through garden displays, educational programs and research trials. The Gardens are open during all seasons and free to the public.