Fall is the Best Time to Grow Cosmos in Warm Climates! Find out what makes this season so promising for planting these classic blooms!
Isn’t fall when all garden things shed, and plants push out the final blooms before diving into dormancy? Not if you live in a warm climate—which makes autumn perfect for growing the spectacular, summer-blooming cosmos! Let’s explore.
Will Cosmos Survive Fall Planting?
Cosmos flowers are usually planted in early spring after the last frost date has passed and then from mid-summer well into fall. They prefer hot, dry conditions, can tolerate poor soil, and need 6-8 hours of sunlight daily for the best blooms!
But this doesn’t mean you can’t plant it in the fall! If you live in a moderate or frost-free zone where the temperatures remain above freezing most of the time, your cosmos will flourish and give you beautiful flowers.
Early to mid-fall is ripe to sow cosmos seeds in the ground for those in zones 8-9 after checking the local frost dates. Cosmos are half-hardy annuals that may tolerate chilly weather, but they will die back with frost.
Germinate the seeds indoors and then transplant them outside to a sunny spot in the garden or in pots. In frost-free zones like 9-11, you can sow seeds directly in the ground in autumn, as long as the soil is well-draining.
Pro tip: Mulch the soil in late fall and early winter and provide frost blankets to insulate your cosmos from extreme cold!
Fall is the Best Time to Grow Cosmos in Warm Climates
1. Ideal for Germination
The ideal temperature range for planting cosmos and getting them to bloom is 60-80 F (15-26 C). You would risk slower or even no germination if you planted cosmos during late spring or summer in warmer regions that exceed 80 F! Here are some tricks to help you.
The conditions in zones 10-11 are better suited for fall and winter planting, as the lowest temperatures mostly remain above 30-40 F.
2. Long Bloom Time
Cosmos germinate anywhere within 7-14 days and start blooming quickly within three months of sowing. You may have to wait 50-60 days for their gorgeous, long-lasting blooms in rose, lavender, pink, crimson, and purple shades.
By planting them in the fall, you can give them a head start on growing and blooming before winter. They’ll flourish as long as the temperatures remain above 55 F (13 C), well into late fall and even early winter in some areas!
Cosmos planted in fall in warmer climates can bloom for up to six months or more, from fall to winter and up to spring, depending on how well you care for them and their variety! These blooms lure in abundant pollinators and sustain color in your garden through the seasons.
Plus, fall-planted cosmos need fewer or no treatments for pests and diseases, simplifying maintenance!
Tips For Planting Cosmos in the Fall
- Pinching or cutting off dead or withered flowers and leaves will encourage your plant to focus its energy on better growth and, of course, more blooms!
- Do not throw away spent blooms! Collect the withered flowers and let them dry. After a month, you can start collecting the seeds by rubbing the flower petals between your fingers.
- Plant cosmos alongside plants that can grow till late fall and early winter, like pansies and verbena. You can also go with zinnias, marigolds, and lantana.
Try planting cosmos in the fall with these tips, and let us know how it goes for you in the comments below! And beyond beauty, did you know the cosmos flower is full of mystery and spiritual symbolism? Read on to find out!
