How to Plant and Care for Dahlias: A Spectacular Flower!

Learning how to plant and care for Dahlias is not hard! Dahlias are spectacular flowers that will impress any and everyone, make a great cut flower, and you can grow your very own variety!

How to Plant and Care for Dahlias 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 1-2 seeds ¼ inch deep or plant the tuber 4-6 inches deep. Plant seeds 9-12 inches apart and tuber 12-18 inches apart.
Water: Keep the ground damp, but not pooling water until the seedling or tuber comes up.
Continued Care: Water regularly, especially when they are 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.

For more detail, my favorite variety, 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. Growing Dahlias From Seeds or Tubers

When to Plant: Unless you live in a long growing season you will want to start your seeds indoors under grow lights. Plant seeds in containers ¼ inch deep 6-8 weeks before your last frost date. (Your last frost date can be found with a simple google search). More details about seed starting HERE. Planting from seeds is more cost efficient, but you have less control on what the flowers are going to look like and have a smaller plant.
Planting from Tubers: After your last frost date plant the tubers 4-6 inches deep, and 12-18 inches apart. Tubers are more expensive, 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.

How to care for dahlias. single dahlia white flower

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 may be necessary if you give heavy wind or rain, which can result in the plant falling over. You can support your plant with a bamboo stake, netting if you have a large row, or planting it 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 a cool, damp, location for next year. If you live in zones 8-11 you can leave your dahlias in the ground.

Dahlia Legacy Garden Idea

Dahlias are like people when it comes to reproducing. Their seeds or children will not be exactly like them, but will have similar traits as the “parent” plant. Each dahlia seed is its own special individual. If you grow one that you like you can keep the tuber, grow out the tuber, and share the tuber. You can have your own signature dahlia variety. My Auntie Doris loved her giant yellow dinner plate dahlias, and when she died we dug them up from her landscape and separated these dahlias to family members. Every summer the dahlias bloom in their glory and it is almost like our loved auntie is visiting us, and we bring her blooms with us to family events and share the flowers with others. Flowers heal the soul.

Common Questions: How to plant and care for Dahlias

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.

Where can I buy Dahlia seeds or tubers?

Many places have Dahlia seeds and tubers but some of my favorites are

Johnny’s Select Seeds

Botanical Interest

Eden Brothers for tubers