How To Plant Dahlia Tubers

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A Beginner’s Step By Step Guide For Planting Dahlia Tubers

A tray full of various dahlia tuber ready to be planted in the garden.

Have you just purchased dahlia bulbs and now you find yourself wondering now ‘how do I plant dahlia tubers?’ Well, you’ve come to the right spot! In today’s post I’m going to teach you how to easily prepare and plant your dahlia tubers so that you have gorgeous dahlia flowers this summer! This beginner friendly, step by step dahlia tuber planting tutorial will help you to grow dahlia flowers this summer.

Close-up of a Castle Drive Small Dahlia growing in our flower field.

I fell in love with dahlia flowers at a very young age. Growing up I remember seeing all the beautiful dahlias grown in my uncle’s garden. When we would visit, there would be gorgeous flower bouquets throughout the house.

I also remember my mother growing quite a few dahlia plants in our yard. She would put the large dinner plate dahlias in vases in our kitchen. I always dreamed of having my own dahlia plants where I could have fresh cut flowers in my home.

Jennifer from The Flowering Farmhouse holding freshly cut dahlia flowers from her cutting garden in 2015.

Fast forward to my adult life and in 2014, I finally started growing my own dahlia tubers. In 2014 my husband and I bought a house that finally had space for a small garden! I couldn’t wait to start planting dahlias.

At first I learned the hard way that you just can’t plant dahlia tubers anywhere. Dahlias need to be planted in specific locations in order to grow big and healthy plants. Do not be intimidated by growing dahlias. If you follow these simple steps below, you’ll be equipped with the knowledge to successfully plant dahlia tubers in your own garden.

When To Plant Dahlias

To get started, you need to know when to safely plant dahlias outside. This varies from growing zone to growing zone. While it can be tempting to get an early start on growing dahlias, your dahlia tubers should not be planted until the ground has warmed and all dangers of frost have passed. The ground temperature should be above 60 degrees before planting out your dahlia tubers. Depending upon your growing season, most areas can plant dahlia tubers outside around mid April through May. 

USDA Plant Hardiness Zone Finder lets you check your last average frost date for your growing zone.

You can use the USDA Hardiness Zone Finder to check when your last average frost date is for your growing zone. As a general rule, this will tell you when it’s safe to plant out your dahlias. Of course, be sure to also check your local forecast for any late forecasted frosts. I typically wait a week or two after our last frost date before planting out in the garden.

Where to Plant Dahlia Tubers

This is where I grew dahlia tubers in 2019. I experimented using a weed barrier cloth around the dahlia plants. I would not recommend this for dahlias.

Knowing where to plant dahlia tubers is important if you want to have big, gorgeous blooms this summer. Dahlia tubers need to be planted in a sunny site that receives at least 8 hours of full sunshine per day. If you are located in a hot climate, find a spot where your dahlias will have morning sun and afternoon shade.

Does Soil Type Matter For Dahlias 

Soil type matters if you want to grow healthy dahlias. Your dahlia tubers will also benefit from being planted in well drained, sandy soil. If you do not know the fertility of your soil, I recommend getting a soil test. A soil test will provide you with important information so you can amend your soil accordingly. Doing so will reward you with more dahlia flowers this summer. Dahlias do best in slightly acidic soil with a pH of 6.5 to 7.

In 2020 we amended our field with good soil. We grew some of the biggest and healthiest dahlia plants we’ve ever grown! Starting with good soil is the foundation for beautiful dahlia flowers.

If your soil is too heavy, you can also amend your soil with sand, peat moss, or compost to improve soil drainage. For small areas you can find these soil amendments at your local nursery or home goods store. It is important though to not add any soil mixes that have additives or fertilizers.

Can Dahlias Grow In Containers

Growing dahlias in containers is typically not recommended unless you are growing dwarf varieties.

Can I grow my dahlias in containers? Typically growing dahlias in containers is not recommended. The best dahlias to grow in containers are dwarf dahlias and low growing varieties. If you do choose to grow dahlia plants in containers, the containers should be at a minimum 15’’ wide by 15’’ deep. You will want to use a mix of garden soil, potting soil (without any additives) and peat moss.

Dahlias grown in containers need frequent watering once they have sprouted. Be careful though to not overwater them as too much water will cause the tubers to rot. You will also want to regularly fertilize your container dahlias to make sure they continue producing beautiful dahlia flowers throughout the season.

How Far Apart Do You Plant Dahlia Tubers

Dahlia tubers laying in the ground, ready to be covered up with soil. The ideal planting distance for dahlias is 12-18 inches apart.

Next, you need to know how far apart to plant your dahlia tubers. Most dahlia tubers need to be spaced at least 12-18 inches apart. This allows for air flow to move freely through your dahlia plant. If your dahlias are spaced too closely together, air can not flow through and you will be more likely to have pest or fungal problems on your dahlia plants.

How Deep To Plant Dahlias

When it’s time to plant your dahlias, begin by making a hole that is 4-6 inches deep. Once you dig the hole, mix in a small handful of bone meal. This will provide important nourishments for your growing dahlia plant.

Bone meal ready to be mixed into soil.

Next, it’s time to put your tubers in the dirt. Begin by placing your dahlia tuber on it’s side with the eye of the dahlia tuber facing up. Gently cover up the dahlia tuber with soil. Now the waiting game begins. Some dahlia tubers can take as long as 4 weeks before you see sprouts above the ground.

It’s important to note that snails and slugs both LOVE dahlias. After covering up your dahlia tubers, sprinkle a light dusting of snail & slug bait around the area. I like to use Sluggo to keep the slugs away from my dahlia plants. There’s nothing worse than finding your new, tender dahlia sprouts have been munched on by slugs.

When Should I Water My Dahlia Plants

Dahlia plants that have recently emerged from the ground. These dahlias have their first true set of leaves and can now be safely watered.

How often you will need to water your dahlias depends a lot on where you are growing your dahlias. Most soil has enough moisture that you do not need to water your dahlias until the first set of true leaves appear on your plant. Watering too soon can cause the dahlia tubers to rot. 

Once your dahlia plants have sprouted their first set of leaves, you should give your plants a deep watering 3-4 times per week. I prefer to use a drip line to provide a good, long soak. With a drip line, I water my dahlias for about 30-60 minutes each time.

Time To Get Growing Your Own Dahlias

Alright, it’s time to get started growing your own dahlias! Hopefully after reading this post, you feel more prepared and confident in planting your dahlia tubers. On my blog, you'll find a FREE printable step by step guide that I’ve created to help you plant your dahlia tubers.

Have you grown dahlias before? As you get more comfortable in growing dahlias, you may even enjoy my blog post How to grow dahlias from seed! Be sure to visit my blog for more on growing your own flowers! And you can check out my complete guide to growing dahlias by clicking here.

Happy Gardening!

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Jennifer Gulizia | The Flowering Farmhouse
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  2 questions
  • Suzzann Suzzann on Feb 13, 2021

    i have planted Dahlias before and they just fell over to the ground, I tried several holders for plants that were not strong enough, for that reason I just gave up. How do you keep them upright?

  • Duane Barkes Duane Barkes on Feb 13, 2021

    I’m in zone 6. Do dahlia overwinter?

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