How to Plant and Care for Dahlias in Pots

Learning how to plant and care for dahlias in pots is not hard! Dahlias are breath taking 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 in Pots Summary:

• Container: Choose a container at least 12 inches in diameter with drainage holes, fill with soil, and place in a sunny location
• Soil: Fill your container with high quality potting soil.
• Planting: After your last frost plant 1-2 seeds ¼ inch deep or plant the tuber 4-6 inches deep. Place the pot in a place that gets at least 6 hours of sunlight.
• 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.  Fertilize your plant every 3-4 weeks with a liquid fertilizer.
  
  For more details on how to plant and care for dahlias in pots and common questions read below!

1. Choose the Right Container

• Size: Ensure the container is large enough to accommodate the flower’s root system. A container that’s too small can stunt growth, while one that’s too large will be unnecessary. You will want a pot at least 12 inches in diameter. 
• Material: Containers come in various materials (plastic, ceramic, terracotta, etc.). Plastic holds water better, while terracotta allows for more air circulation. There are also grow bags that are great for storing and affordable, but will not last long. You decide what you like best, because you can use any container.
• Drainage: Your container must have holes at the bottom for excess water to drain. Many plastic pots do not have holes at the bottom, so make sure you make the hole before filling the pot with soil. If your pot doesn’t have drainage holes water will accumulate at the bottom and can cause root rot.

2. Use High-Quality Potting Mix

• You can use garden soil, but it can become compacted in containers. Using a good-quality potting mix that is well-draining will benefit your plants. If I am filling a large pot I will use some dirt from my garden for the bottom half and potting soil from the top half to save money.  
• I also like to add some worm casting to my soil to give it the extra nutrients that many potting soils are lacking. Worm casting can be found at any big box store by the fertilizers.
• Dahlias need at least 6 hours of sun. Place your pot in a location that has this amount of sun.

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.

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. Feed Your Dahlias THE KEY

• Plants being grown in pots do not have the access to the nutrients in the ground, so you will need to fertilize more often. 
• I add worm castings in the spring when I first plant and then fertilize every 3-4 weeks with a liquid fertilizer.

9. 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. Or move your container indoors or in the garage. If you live in zones 8-11 you can leave your dahlias in the pot.

Common Questions

Now you know how to plant and care for dahlias in pots here are some common questions!

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

Now you know how to grow dahlias in pots you can see it’s not hard! I can’t wait for you to experience delightful dahlias this year!

As always, 

Grow flower to heal your soul,

Beth