Are Dahlias Perennials?

Are Dahlias Perennials?

Short Answer: Dahlias are technically perennials but are often treated as annuals in climates with freezing winters. Dahlias can survive and bloom annually in warmer regions where the ground doesn’t freeze. In colder areas, their tubers must be dug up and stored indoors during winter for replanting the following spring.

No wonder many dahlia growers ask, “Are dahlias perennials or annuals?” Dahlias often bloom with the vitality of favorite annual plants like zinnias and marigolds. From mid-summer until frost, they’ll unfurl flowers ranging from tiny, petal-packed, button-like blossoms to blooms bigger than a dinner plate. However, these plants grow from bulb-like tubers that can survive winters like perennial plants. To ensure your dahlias return next year, you may have to help them, depending on your growing zone. Here’s what you need to know to overwinter dahlia tubers to enjoy them successfully year after year.

Are Dahlias Perennial in Your Zone?

Dahlias are native to the mountains of northern Mexico. They are hardy, or perennial, in tropical and warm climates, springing up from the ground each spring. Generally, dahlias are perennial in Zones 8 and above. In Zones 7 and below, dahlia’s fleshy roots—called tubers—are killed by cold temperatures.

If you garden in Zone 7 and below, you don’t have to say goodbye to your dahlias and begin with fresh tubers next year. Overwinter dahlias by digging them up in late fall and saving them in a frost-free place until it’s time to replant in spring.

close up pink purple red dahlias

How to Overwinter Dahlias

Dahlias can be tricky to dig up and save over the winter. Many cold-region gardeners opt to grow dahlias as annuals, buying new plants each year. Overwintering dahlias takes patience, persistence, and some trial and error.

Moisture is a common cause of overwintering trouble: too much moisture or too little spells doom for dahlia tubers. Poll a few Dahlia experts, and you’ll come away with an array of tips and tricks for getting the balance of moisture just right. But in essence, these all boil down to five key steps to overwintering success.

1. Wait It Out

Allow dahlia foliage to completely die back to the ground in the fall before digging the tubers. While a light frost will damage flowers and some foliage, the plant will continue to grow actively. Wait to dig the tubers until a killing freeze zaps all the foliage. For best results, watch the forecast and leave tubers in the ground for a week or more after the killing freeze to allow them to continue maturing. Dig the tubers as soon as low temperatures regularly dip to freezing.

2. Dig Carefully

Dahlia tubers are soft and fleshy and loosely held together by underground stems. Lifting them out of the ground requires some gentleness to avoid damaging them. Use a potato fork or shovel to loosen soil around the clump, working at least 1 foot away from the main stem. Carefully lift the clump of tubers out of the ground and brush away soil clinging to the individual tubers.

3. Cure Dahlia Tubers

The tubers are very soft when they come from the ground in the fall. Encourage them to harden or cure by spreading them in a well-ventilated, shaded area for a few days. A covered porch or garage can be a great place to cure dahlias. Make sure to protect them from freezing temperatures.

4. Store Well

Moist, ventilated storage is key to overwintering dahlia tubers. A storage place that is damp but not ventilated will cause tubers to rot. A well-ventilated location without adequate moisture will cause tubers to dry out and shrivel up. Experts recommend balancing moisture and ventilation by packing tubers in ventilated boxes or baskets. Place the tubers upside down, allowing plenty of space between the clumps.

Test Garden Tip: Use a permanent marker to label the tubers with various names so you don’t have to keep track of labels.

Cover the clumps with a 4- to 6-inch layer of moist vermiculite or fine wood chips, such as commercially sold pet bedding. Exactly how wet the vermiculite or wood chips should be depends on the humidity in your storage area. Begin by creating a less moist packing material. Then, you can easily add water if the tubers appear to be drying out. Store the ventilated box or basket in a garage, basement, or minimally heated place between 35 and 50°F. Avoid locations with hot or cold drafts or that are too damp or extremely dry.

5. Check In

Pull back the packing material and check the tubers every couple of weeks. If the tubers appear dry or shriveling, lightly sprinkle the media with water. Get a jump start on the growing season by planting tubers in pots about four weeks before the last spring frost date. Grow them in a bright, sunny window or under grow lights and transplant them into the garden when all danger of frost has passed.

Most Popular Flowers & Plants in the USA

RegionPopular FlowersPopular Plants
Northeast (e.g., New York, Massachusetts)Rose, Purple Lilac, Mountain LaurelSugar Maple, American Elm, White Pine
Southeast (e.g., Florida, Georgia)Orange Blossom, Cherokee Rose, Southern MagnoliaLive Oak, Spanish Moss, Saw Palmetto
Midwest (e.g., Ohio, Illinois)Carnation, Violet, Purple ConeflowerBur Oak, Prairie Grasses, Wild Bergamot
Southwest (e.g., Texas, Arizona)Bluebonnet, Saguaro Cactus Flower, Indian PaintbrushJoshua Tree, Agave, Mesquite
West (e.g., California, Washington)California Poppy, Coast Rhododendron, BitterrootGiant Sequoia, Redwood, Manzanita
Rocky Mountain (e.g., Colorado, Montana)Rocky Mountain Columbine, Bitterroot, Indian PaintbrushBlue Spruce, Aspen, Sagebrush
Great Plains (e.g., Kansas, Nebraska)Sunflower, Goldenrod, Purple ConeflowerCottonwood, Bluestem Grasses, Buffalo Grass
Pacific Northwest (e.g., Oregon, Alaska)Oregon Grape, Forget-me-not, Pacific RhododendronDouglas Fir, Western Hemlock, Ferns

This table includes the most popular flowers and plants in the USA by region, which considers a range of botanical species, including native and widely cultivated varieties.

Most Popular Flowers & Plants in Australia

RegionPopular FlowersPopular Plants
New South WalesWaratah, Bottlebrush, Flannel FlowerEucalyptus, Acacia, Banksia
VictoriaCommon Heath, Waxflower, Pink HeathMountain Ash, Silver Wattle, Victorian Blue Gum
QueenslandCooktown Orchid, Golden Penda, Umbrella Tree FlowerMoreton Bay Fig, Macadamia Nut, Queensland Bottle Tree
South AustraliaSturt's Desert Pea, Kangaroo Paw, Eucalyptus BlossomAdelaide Blue Gum, South Australian Blue Gum, Saltbush
Western AustraliaRed and Green Kangaroo Paw, Mangles Kangaroo Paw, Swan River DaisyJarrah, Marri, Karri
TasmaniaTasmanian Blue Gum, Leatherwood Flower, Tasmanian WaratahHuon Pine, Tasmanian Oak, Myrtle Beech
Northern TerritorySturt's Desert Rose, Frangipani, Desert RoseBoab, Gidgee, Spinifex
Australian Capital TerritoryRoyal Bluebell, Australian Daisy, CorreaSnow Gum, River Red Gum, Black Mountain

This table offers a basic overview of popular flowers and plants in each Australian region, focusing on a combination of state flowers, native species, and other characteristic plants. It's important to note that specific species' popularity and prevalence can vary. This table is a simplified representation. Consulting local botanical gardens or regional horticultural societies in Australia would be ideal for more detailed and accurate information.

Charlotte Gammon

By Charlotte Gammon

Meet Charlotte Gammon, our expert and author. She's our true treasure, as she has got 20+ years of experience in gardening, winery and house design. In early 2000s, she worked for magazine and was in charge of the gaardening section. Later on, Charlotte opened her own designer agency and worked as a designer and decorator. We are happy to have Charlotte with us, as she is our good friend. We value her experience and we're sure you will love the articles she created for our blog.