How to Grow Dahlias from Tubers: A Flower You Need To Experience

Learning how to grow Dahlias from tubers is not hard and you can have flowers that take your breath away every summer! Dahlias are spectacular flowers that will impress any and everyone, make a great cut flower, and there are so many varieties to choose from!

How to Grow Dahlias From Tubers Summary:

• Soil: Break up your soil and get rid of any weeds or grass. If needed add a layer of compost.
• Planting: After your last frost plant the tuber 4-6 inches deep with the stem up. Plant tubers 12-18 inches apart. 
• Water: Keep the ground damp, but not pooling water until the tuber comes up. 
• Continued Care: Water regularly, especially when the plant is young and establishing roots. Once about a foot tall Deep water once a week at the base of the plant. Water 2-3 times a week during hot summer spells. If your soil is low in nutrients Fertilize the plant with a liquid fertilizer once a month. 

For more detail and common questions read below!

1. Choose the Right Location

Dahlias need full sun to thrive, so select a spot that gets at least 6-8 hours of direct sunlight a day. They prefer warm, well-draining soil.

2. Prepare the Soil

Prepare your soil by clearing any grass or weeds. Then loosen your soil with your hands or shovel. 

Dahlias grow best in rich well-draining soil. You can improve your soil by mixing in some compost if your soil is dense and hard. If your soil is sandy or very loose, adding some compost will help retain moisture and provide nutrients.

3. How to Grow Dahlias from Tubers

• Planting from Tubers:  After your last frost date (which can be found with a simple google search) plant the tubers 4-6 inches deep, and 12-18 inches apart. Tubers are more expensive than seeds, but you know exactly what the flowers are going to look like and have more varieties to choose from. 
• Water: Keep the ground damp, but not pooling water until the seedling comes up.

4. Watering

Dahlias need regular watering, especially when they are young and establishing roots. However, they do not like to sit in waterlogged soil. Once the plant is about a foot tall, water the base of the plant to avoid wetting the foliage, which can lead to fungal diseases. Deep watering once a week is typically enough, but in hot weather, they may need more frequent watering such as every other day or twice a week.

5. Pinching- The Way to an Abundant Harvest

If you would like to increase your harvest, you need to “pinch” your plant. This will force the plant to send up two main stems instead of one, resulting in more flowers for you! Once the plant has 5-6 sets of leaves cut or “pinch” the top set of leaves off the plant. If I plant a lot of dahlias I will pinch all but one plant because the plant that I don’t pinch will bloom sooner, but not as many. Then I get to enjoy flowers sooner, while not giving up my harvest amount.

6. Staking

Giving your dahlia plant support may be necessary if you get heavy wind or rain, which can result in the plant falling over. You can support your plant with a bamboo stake and string, netting if you have a large row, or planting it up against a fence or house.

7. Harvesting for Cut Flowers

Cut dahlia flowers in the cool of the morning or evening. Dahlia flowers will not open anymore once cut from the plant so harvest when it has just fully opened for the longest vase life.

8. End of Season Care & Storing Tuber

After the first frost or late fall when your plant has died you can dig up your tubers to store for the winter in soil or peat moss  in a cool, damp, location for next year. If you live in zones 8-11 you can leave your dahlias in the ground. I have seen some gardeners in colder zones heavily mulch and tarp their tubers so they do not have to dig them up, but I have not personally tried this.

Common Questions

Do you soak dahlia tubers before planting?

No, you do not need to soak your dahlia tubers before planting.

Can I plant dahlia tubers straight into the ground?

Yes! Once your last frost has passed your ground will be warm enough to plant.

What is the secret to growing dahlias?

Good Soil, Water, and lots of Sun!

How do I keep Dahlias blooming all summer?

Dahlias will keep blooming and blooming as long as you continue to cut the dead flowers off the plant, and keep the plant healthy.

How tall do Dahlias grow?

How tall the Dahlias can grow will depend on the variety, unless it is a container variety the plant can grow up to six feet tall!

Do Dahlias come back every year?

Yes, if you live in zones 8-11. If you live in colder zones the tubers will turn to mush in the ground if you do not dig them up and properly store them for next year. Some people in zones 6 & 7 have had success covering tubers in the winter with a tarp and deep mulch to keep the tubers from freezing.

What temperature will kill Dahlias?

Dahlias are frost sensitive. When night temps are below 32 degrees they will die.

Do Dahlias need full sun?

Yes, dahlias need 6-8 hours of full sun.

What month do you plant Dahlias tubers?

Plant dahlia tubers after the last frost in spring when your night temperatures are no lower than 32 degrees. Usually anytime April-June, but check your weather and last frost date to be sure. Plant dahlia seeds 6-8 weeks before your last frost indoors.

What happens if you plant dahlias too close together?

If planted to close the plant will not grow as large, and dahlias can get fungal disease.

Now you have learned how to grow Dahlias from tubers you can see it’s not hard. I can’t wait for you to experience the delight of dahlias this year!

As always, 

Grow flower to heal your soul,

Beth