Growing Dahlias is easy but they cannot tolerate frosts
Dahlias are a tropical plant with gorgeous flowers, but you have to grow them during the warmer months. For our zone 5b, planting dahlias in our flower garden means some extra care.
Dahlias need to grow and bloom during the frost-free window.
If you don’t know your growing zone you can easily look it up in google by typing your location & growing zone.
Dahlia tubers or seed?
In general, it’s much easier to grow dahlia flowers from the tubers, not by growing seedlings. Dahlia bulbs are actually tubers, and you plant them in the spring and pull them up in the fall.
Here are some tips for growing dahlias from sprint to fall
Planting dahlias in the spring
Dahlia tubers are planted in the spring after the risk of frost. You can plant them a week earlier with frost protection fabric too. If you don’t get frosts then you don’t have to worry about this, it means you have a warmer climate to garden in!
I did grow them from seed too to experiment, and those seedlings did bloom. It’s SO much more work though, and honestly, not worth it. Sometimes buying seeds means more variety, but this isn’t the case with dahlias.
Dahlia types & where to buy them
You can buy dahlia bulbs from most garden centers or check for local flower farms. A lot of people also order them online, a popular one being Floret farm. There are many gorgeous dahlias, we were thankful to find a local dahlia farm Stone Meadow Flowers.
Dahlia sizes and shapes
Dahlia size can be pom pom to giant size. Dinner plate dahlia size is a popular one too!
Dahlia flower forms:
- AN- Anemone
- BA- Ball
- C- Cactus
- CO- Colarette
- IC- Incurved Cactus
- ID- Informal Decorative
- FD- Formal Decorative
- MB- Miniature Ball
- P- Pom pon
- SC- Semi-cactus
Be sure to draw a garden sketch of your dahlia types and where you planted them
Where should you plant dahlias?
Dahlias prefer full sunshine. Loose soil works best for dahlias so the tubers have the space to expand. Your instructions should have spacing and depth requirements, but they grow roughly to the size of a rose bush.
The larger varieties need staking, especially dinner plate dahlias.
Stake a post on either side of the tuber when planting so you don’t damage the tubers later on. If you want to grow dahlias in containers, consider smaller flower sizes.
Enrich the soil with compost and add a light amount of organic fertilizer.
I used the perfect blend and azomite. You’ll want an organic fertilizer suited to blooming flowers, but as you need to save the tubers that’s also important. Don’t overfeed.
Fall Dahlia Tuber Care
Dahlias are hardy to zone 8, sometimes zone 7 can offer protection for the winter. Other growing zones will need to dig out the tubers and overwinter them indoors. I waited until a light frost killed the above plant then harvested the tubers.
Pulling up Dahlia tubers
- Pinch off the stem and the above ground plant matter
- Gently remove soil around dahlia base
- You should see tubers under the soil, gently lift them out
- Separate your tubers from the central one.
- Label them so you know what varieties you have for next spring
- Brush off any dirt. Be gently handling them so they don’t become damaged
- Allow the tubers to completely dry in the sun
- Label the variety and store in peat moss or wood shavings in a cool place (garages or cooler basements work well)