In the highlands of Mexico where dahlias originated, the nights are always cool, and most varieties today still need those cool night temperatures to grow and bloom well.
Some are more heat-tolerant, though, and we recommend these through zone 8 in the South and Southwest – as noted in our dahlia chart.
To expand our list of heat-tolerant dahlias, we’d like to hear from you if you garden in zone 8 or warmer in the South or Southwest. Which of our dahlias have thrived for you, and which haven’t?
Here’s one recent success story from zone-8b Mobile. Our good customer Glenda Snodgrass emailed us last November to say her mother-in-law, Barbara Adair, bought a ‘Thomas Edison’ dahlia with a gift certificate Glenda had given her. “I told her dahlias couldn’t be grown in Mobile, but she said her mother always had dahlias here, and I’ve had to eat some crow because it bloomed last week and it’s beautiful!”
Barbara grew her dahlia in a large clay pot on her deck. (Pots can be tough for dahlias, but see our Bulbs in Pots page for tips.) “North side, full sun in morning, some shade during the day, until late afternoon full sun,” she explained. By mid-October the plant was six feet tall and the first flower opened. “It’s a darker purple than in your catalog,” Barbara wrote, “a real beauty!”
Read more success stories and tips at our Dahlias for Hot Nights page.
And please help us guide other gardeners by telling us how our dahlias have done for you in the heat of the Deep South and Southwest. Thanks!
