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The Flower Show

For the Love of Plants: Late Blooming Perennials

October 05, 2020

leaf icon plants

Symphiotrichum oblongifolium raydon_ Perennial-Flower

While some plants and shrubs are winding down for the fall, late-blooming perennials offer gardeners many exciting options to enhance their seasonal palette. "As we move into October, I know I'll have asters, toad lilies, goldenrods, and Rudbeckia to look forward to," says Andrew Bunting, PHS Vice President of Public Horticulture. Andrew offers some tips and fall favorites: 

Q. Are there any late-blooming perennials you highly recommend?
A.  Symphyotrichum oblongifolium ‘Raydon’s Favorite’, (pictured above) an aromatic aster, comes to mind first. This tall beauty will reach up to three feet in height and will continue blooming for a few weeks in October. Its radiant violet-blue, daisy-like flowers with deep yellow centers are easy to grow, long-lived, and a great source of nectar for pollinators. Another aster in the same family, ‘October Skies’ will blossom with rich sky-blue flowers, also with yellow centers, through October as well.

Begonia grandis (Hardy Begonia) is another show-stopper come October. These tuberous perennials are noted for their exquisite and lush foliage of winged-shaped, olive green leaves, with red veining and colorful underside. Nodding pink or white flowers will blossom mid-September to Mid-October, for a month of late season color. 

Rudbeckia substomentosa ‘Henry Eilers’, commonly called sweet coneflower, features daisy-like flowers with yellow rays and dark brownish-purple center disks. This clump-forming perennial will add a bright, happy spot to any garden between September and October.

Kirengeshoma palmata, (Yellow Waxbells) is a rare, connoisseur-type plant with smooth maple like leaves, tipped with nodding creamy yellow bells. Flowers appear in September rising above the leaves on purple-black stems and bloom through mid-October. 

Q. Where can we find a good selection of fall perennials? 
A.  There are a host of a great garden centers in our region like Primex Garden Center in Glenside, Mostardi Nursery in Newtown Square, Gateway Garden Center in Hockessin, Delaware, and Marano Gardens in Fort Washington. For more specialized items, there are many great mail order nurseries.

Q. Is there still time to plant perennials that will bloom next fall?
A. In the Delaware Valley, planting of perennials can continue well into November. While the air temperatures might be cool the soil is relatively warm and the key with perennials planted in the fall is to establish a good root system going into the winter.

Q. Are any of your favorites good for a shady spot?
A. Most of these plants love full sun and are very resilient to poor soils. Begonia grandis likes the shade as does Kirengeshoma, which is ideal for planting in a cold, damp woodland garden. Pick the right plant for the right condition.  Always be mindful of sun versus shade, but also understand if a plant likes well-drained soils or can take moist conditions.

Q. After they are finished blooming, do I need to cut them back?
A. For all these perennials, you can let the frost and then the freezing kill the foliage. When they don’t look ornamental anymore, you can cut them back.

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