Perennials to plant in September

Perennials are everyone’s favorite these days. Many fall and spring-blooming perennials do especially well when planted in September. While some perennials planted now won’t bloom right away, if planted now they should have enough time to establish their root system before the first frost. This helps to prepare them for strong, beautiful blooms in the spring. Plus, they won’t face the threat of heat or drought from the hot summer months. This also means less work in the spring when annuals demand most gardeners’ attention. Perennials are hard to beat. Consider the following six perennials for planting in September.

Penstemon (Penstemon digitalis) has a long bloom season in the spring and summer, sporting purple and white tubular flowers that are great for luring hummingbirds to your yard. You can plant seedlings of this perennial anytime in the spring, summer, or fall in USDA hardiness zones 3 to 8. September is an ideal time to plant, depending on your climate, because the plant needs at least 4 weeks to become established before the first frost. This will also ready the plant to bloom the following season. 

Bee Balm (Monarda didyma) grows in USDA hardiness zones 4 to 9 and blooms in summer. However, this is a perennial that you should deadhead for blooms that keep coming well into the fall. Bee balm can be planted in the ground in the spring or the fall, but placement is more important than timing. These stunning pink flowers are great for attracting pollinators to your garden, but they are susceptible to problems caused by shade and too much moisture, particularly mildew and fungus. They prefer full sun, well-drained soil, and plenty of space.

Blazing star (Liatris spicata) has 50 different varieties that grow in USDA hardiness zones 3 to 8 and produce blooms in the summer. However, it takes a few seasons for this plant to start flowering. Transplants should only be planted in the spring, but seeds can be sown in September because they need cold to properly germinate. Put the seeds in your fridge for 4 to 6 weeks before planting in September.

Hellebore (Helleborus) is a spring-blooming perennial with beautiful cream, green, pink, purple, red, or white flowers that should be planted in the fall in USDA hardiness zones 5 to 8. Hellebore can also bloom in winter once it’s fully established. September is the perfect time to plant the seeds because they need to chill in moisture for 60 days to germinate. Hellebore can take up to four years to fully bloom, though some blooms may appear in year three. These flowers make great ornamental additions to shade gardens, but note that they are toxic to humans if eaten.

Japanese anemone (Anemone x hybrida) grows beautifully in full sun and partial shade in USDA hardiness zones 4 to 8. It produces pink, purple, or white blooms in both fall and summer. While they can be planted at any time, September is particularly favorable due to the warmer soil leading into the cold season. Japanese anemone is most frequently sold as seedlings in the early fall. Japanese Anemone is picky, so you should take care to plant it somewhere that stays moist but not too wet. In drier conditions or locations, you may need to mulch over winter.

Stonecrop (Sedum spp) grows in shallow soil in USDA hardiness zones 3 to 10, making it a fantastic ground cover for rock gardens. You can expect to see blooms in the summer and fall. It does best in full sun, especially in regions with cold winters. You can plant stonecrop anytime in spring or late summer. For southern climates, you may be able to plant later in September or even into October.

Tim Lewis is a Georgia Green Industry Association Certified Plant Professional, gardening writer, and former Perry High School horticulture instructor. He can be reached at (478)954-1507 or timlewis1@windstream.net.