7 Best Perennials to Plant in September Before the Weather Gets Too Cool
- glennhrussell77
- Sep 4
- 5 min read
Updated: Oct 6
Don’t put away those trowels yet—September is prime time for planting these reliable garden favorites.
By
Published on September 03, 2025
Are You Cleaning Your Cleaning Tools?
Planting perennials in September may feel like you’re a step or two behind the growing season. However, it’s actually one of the smartest moves you can make for a better garden next year. Cooler (but not frozen) temperatures and increased rainfall provide some plants with just enough time to establish strong root systems before winter. This timing can lead to healthier, more resilient growth and denser blooms once spring arrives.
According to the garden experts we spoke to, the key is choosing varieties that specifically benefit from being planted in early fall. You also need to be able to get your hands on a transplant or start from a local nursery. To give you a little head start, we’ve rounded up the best perennials to plant in September. This way, you can enjoy lush, long-lasting color in the seasons to come.
Laura Janney, plant expert and the founder of The Inspired Garden Masterclass
Fran Parrish, flower farmer, event florist, and the founder of Heirloom Soul Florals
Why Plant Perennials in September?
Planting perennials in September allows them to take advantage of the cooler temperatures and increased moisture. This helps them establish strong roots before the winter frost sets in. As a result, they will thrive better in the spring. Additionally, September planting can lead to vibrant blooms and a more colorful garden.
1. Yarrow
Fran Parrish, a flower farmer and event florist, believes yarrow (Achillea millefolium) should be planted in September. The cooler temperatures and frequent rain mean the plant won't dry out or get stressed as it would in the heat of summer.
“Yarrow is one of the most popular cut flowers on our flower farm because it comes in so many colors and is a native perennial,” says Parrish. “It is a critical food source for native pollinators. Yarrow is also drought-tolerant and does not require any fertilization to bloom spectacularly in early summer and again in fall.”
USDA Hardiness Zones: 3-10
Bloom Time: Blooms for eight weeks starting in early summer, then again in early fall when the plant is cut to the ground.
2. Butterfly Milkweed
Known for its vivid orange clusters, butterfly milkweed (Asclepias tuberosa) is one of the most pollinator-friendly perennials you can add to your garden in fall. Most varieties are tough enough for poor soils and dry conditions, making it the perfect choice for those who prefer low-maintenance landscapes. Plus, you can cut the vibrant stems for long-lasting arrangements.
“Another favorite cut flower on our flower farm is butterfly milkweed with its uniquely-shaped, bright orange flower heads,” says Parrish. “Butterfly milkweed is a must-grow for everyone in zones 3-10. It is a drought-tolerant native plant and a host plant and critical food source for monarch butterfly larvae.”
USDA Hardiness Zones: 3-10
Bloom Time: Blooms for four weeks in early summer, then again in fall when the plant is cut to the ground.
3. Catmint
Catmint (Nepeta racemosa) is an ideal perennial to plant in September. It is somewhat drought tolerant. Once established, it will need very little maintenance throughout the fall. It’s also one of those plants that is typically available for purchase this time of year.
“There’s a reason catmint is usually available at the nursery. Catmint is not only long-blooming but very hardy and easy to care for,” says Laura Janney, plant expert and CEO of The Inspired Garden Masterclass. “It has light, dusty-green foliage growing in soft spikes filled with tiny purple blooms. There are larger varieties that will take up space in your garden or shorter varieties if you’re looking for a border plant.”
USDA Hardiness Zones: 3-8 (although some varieties can handle zone 9)
Bloom Time: Starts flowering in late spring and can go all summer with deadheading.
Janney notes that the perennials you typically find at nurseries will start depleting in early or mid-summer. However, you can take advantage of end-of-season sales. “If you are lucky to have a good garden friend dividing perennials, that is another way you can get spring-blooming perennials installed in the autumn season,” she adds.
4. Salvia
When planted in early fall, salvia (Salvia nemorosa) has time to develop strong roots before winter. This sets it up for denser blooms the following spring. This hardy perennial produces upright spikes of violet-blue flowers. Its drought tolerance and ability to thrive in poor soils make it another consistent performer.
“Salvia is a wonderful plant because it’s hardy, reliable, and an early spring bloomer,” says Janney. “It’s great to have some color when most of the perennials haven’t bloomed yet. I love how the spikes contrast with the roundness of the other blooms. I even love the texture of salvia’s spent blooms.”
USDA Hardiness Zones: 5-9
Bloom Time: Late spring to early summer, with potential to rebloom with fall deadheading.
5. Tickseed
Plant tickseed (Coreopsis) when the soil is still warm and the air is cool. “The cool air signals to the plant to focus on the growth of strong roots and not to put energy into the flowers,” says Janney. This perennial is very resilient when planted in the fall. It’s more likely to survive the winter and can handle a range of soils.
“With its autumn vibrant hues, it should be readily available at the nursery,” she continues. “Coreopsis is technically deer resistant, but keep in mind this flower isn’t as resistant as some others. Some varieties do better with deer than others. Always do your research.”
USDA Hardiness Zones: 4-9
Bloom Time: Typically blooms from early summer through fall.
6. Veronica
Plant Veronica (Spike speedwell) in full sun and well-draining soil when the temperatures are cooler in early fall. According to Janney, this hardy perennial is low-maintenance and adaptable, making it a reliable choice for borders and mixed beds.
“We use it in practically all of our designs because the texture is so striking and plays nicely with most perennials,” says Janney. “We particularly love how Veronica contrasts the softness of other plants with more rounded foliage. It looks like paintbrushes in your garden! And it is deer resistant.”
USDA Hardiness Zones: 4-8
Bloom Time: Late spring to midsummer, with potential rebloom in late summer if cut back.
7. Wild Bergamot
Wild bergamot (Monarda fistulosa), also known as bee balm, has stunning lavender blooms. The plant releases a clean, minty scent that naturally repels some pests while attracting beneficial pollinators like butterflies and bees. More importantly, it’s a dependable native perennial that you should be able to spot in local nurseries this time of year. Mix it into borders or meadow-style gardens to add texture and height.
“Wild bergamot is yet another drought-tolerant native plant with tall stems and a spreading growth habit,” says Parrish. “It does a wonderful job of filling in pesky empty spots in the yard while blooming tall as a lovely background plant. Blooms can be harvested and dried for herbal tea.”
USDA Hardiness Zones: 3-10
Bloom Time: A short-lived beauty that blooms for three to four weeks in early summer.
Conclusion
Planting perennials in September is a strategic way to prepare your garden for the upcoming seasons. By choosing the right varieties, you can ensure a vibrant and thriving garden come spring. Whether you opt for yarrow, butterfly milkweed, or any of the other fantastic options, your garden will be well on its way to becoming a colorful oasis.
This is a fantastic article we wanted to share with you from the Realsimple.com site:
