A Beginner’s Guide To Growing Dahlias (2024)

Everything You Need To Know To Successfully Plant, Grow, and Care For Your Dahlia Flowers

If you are thinking about growing dahlias, you’ve come to the right spot! I’ve created this beginner’s guide to dahlias so that you too can enjoy gorgeous dahlias in your cut flower garden this summer.

To say that dahlias are my favorite garden flower, that would be an understatement. I fell in love with dahlia flowers at a very young age. These beautiful flowers have always been a favorite of mine! My mother grew dahlias in our backyard garden and my uncle also had a huge dahlia garden in Seattle. One of my favorite childhood memories was seeing fresh cut dinner plate dahlia flowers in the house. From the time I was very little, I was determined to grow my own dahlias someday.

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Table OF CONTENTS

How I Got Started Growing Dahlias

I first started growing dahlias in my own backyard in 2014. That summer of 2014, I bought 16 dahlia bulbs at Costco and online to plant in my flower garden. Little did I know back then that I was just beginning my journey in growing dahlias. The next summer I grew 64 dahlia plants!

Fast forward to now and I am currently planning out our 2021 flower farm where I will be growing somewhere between 700-900 dahlia plants. For me, it’s like the old saying with potato chips, you can’t have just one.

Adding More Dahlia Tubers To My Garden

Every year since 2014, I’ve been able to multiply my dahlia tuber bulbs by dividing them. It’s amazing how single tubers multiply in the course of one year! These tuberous roots can multiply and create on average 3-10 new tubers for the next growing season. Of course I’ve also added many dahlia varieties along the way. In 2020, I grew close to 40 varieties of dahlias (not including the ones I started from seed). This year (2021) I will be growing over 60 different varieties of dahlias.

While I may be growing almost 1000 dahlias, I actually have several thousand dahlia tubers! You can actually find some of my favorite dahlia tubers for sale in our online shop by clicking here.

“Don’t wait for someone to bring you flowers. Plant your own garden and decorate your own soul.”

— Mario Quintana

Are You Ready To Start Growing Dahlias?

Hopefully you’ve found yourself here today because you too have a desire to learn how to grow dahlias. Keep reading and I will do my best in this beginner’s guide to dahlias to guide you in the right direction so that you can successfully get started with planting, growing, and caring for your own dahlia flowers. Whether you are a beginner in the garden or an experienced gardener, I hope you will learn something new about growing dahlias in this post.

What Are Dahlias?

Dahlias originate from Mexico and would you believe that they were once eaten just like a potato plant. Can you imagine growing gorgeous dahlias to eat the tubers? Crazy, huh? In my wildest dreams I can’t imagine growing dahlias just to eat their tubers.

What Are Dahlias According to Wikipedia

According to Wikipedia, a “dahlia is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico and Central America.” Dahlias are a member of the Asteraceae family. They are closely related to sunflowers, daisies, chrysanthemums, and zinnias. There are hundreds of different varieties of dahlias. All dahlia plants produce single stem flowers ranging from 2 inches in diameter to a foot wide. Most dahlias do not produce any scent and they attract pollinators to the garden through their bright colors.

Types of Dahlias

There are hundreds of different varieties of dahlias. All dahlia plants produce stems of single flowers ranging from 2 inches in diameter to a foot wide. Most dahlias do not produce any scent and attract pollinators through their bright colors. Dahlia plants also range in height with some as little as a foot tall and others growing to upwards of 6 or 8 feet in height.

Types of Dahlia Varieties

There are hundreds of varieties of dahlias. However, all varieties are broken down into specific types of dahlias. Within each of these types, many different varieties exist. Now, let’s take a look at the different types of common garden dahlias. These pictures show different dahlias ranging from pom pom to decorative dahlia to dinnerplate dahlias to cactus dahlias. The flower form and flower size can vary greatly from variety to variety. There are over 50,000 classified dahlias in the world!

Dahlia Tubers VS Dahlia Seeds

While many garden flowers are planted by seed, most dahlias are planted as a bulb referred to as a dahlia tuber. If you see a variety of dahlias that you like and you want to grow the same plant, then you must start with a dahlia tuber. By planting a dahlia tuber, you will grow an identical plant from the mother plant.

Dahlia plants produce tubers that grow in the ground. Each year the mother tuber (the original bulb) typically produces anywhere from 5-20 new tubers. By dividing these tubers in the winter, you can multiply the original plant and grow identical dahlia flowers.

Growing Dahlias From Seed

Growing dahlias from seed is very different from growing dahlias from tubers. When you grow dahlia flowers from seed, no two plants will ever be the same! That’s right, by growing dahlia flower seeds, you are actually creating a new variety of dahlias that’s never been grown before. Whereas when you plant a dahlia tuber, it will grow an identical plant from the mother tuber.

Growing Dahlia Seeds

Dahlia flower seeds get their genetic makeup from the seed parent as well as the pollination of bees. That’s right, the bees and other garden pollinators actually play a huge role in determining what your dahlia seeds will eventually grow. The bees carry pollen from one dahlia plant to the next and actually modify the genetic make-up of the dahlia seeds. Most dahlia seeds will grow single or semi-double blooms with an open-center. You can learn more about growing dahlias from seed by clicking here to read my in-depth post on growing dahlias from seed.

Where To Buy Dahlia Bulbs

Nowadays it seems that you can buy dahlia tubers (sometimes referred to as bulbs) almost anywhere. I do however recommend that you choose to buy your dahlia tubers from a reputable grower or wholesaler. Reputable growers are less likely to have disease or viruses present in their tubers.

Some of my favorite online dahlia tuber sources:

• –The Flowering Farmhouse
• –Bear Creek Farm
• –Floret Flowers (currently not selling tubers, but have an amazing seed collection)
• –Swan Island Dahlias
• –Tall Grass Farms
• –Triple Wren Farms
• –Dahlia Addict (An online resource guide that lists many growers throughout the U.S. & Canada)

Where to Buy Dahlia Tubers In Canada:

• –Creekside Growers
• –Dahlia Addict (An online resource guide that lists many growers throughout the U.S. & Canada)

Planting Your Dahlia Tubers

Where To Plant Dahlia Tubers

To begin, you will need to decide where to plant your dahlia tubers. Your dahlias need full sun with at least 6 to 8 hours of direct sunlight per day. Choose a sunny spot with morning sunlight. If possible, try to find a wind protected spot to plant your dahlia tubers.

Good Soil Is Important If You Want To Grow Beautiful Dahlias

Dahlias will also benefit from being planted in well drained, sandy soil. If you do not know the Dahlias are heavy feeders that benefit from being planted in well drained, sandy soil. If you do not know the fertility of your soil, I recommend getting asoil test. A soil test will provide you with important information so you can amend your soil accordingly to have rich soil to feed the dahlia root system. 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.

When To Plant Dahlias

To get started, you need to know when to safely plant dahlias outside. Planting time varies from Most people plant dahlias in early spring. To get started, you need to know when to safely plant dahlias outside. Planting time varies from growing zone to growing zone, but is always after danger of frost has passed. 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 soil temperatures 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.

USDA Plant Hardiness Zone Finder

If you do not know 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.

How To Plant Dahlias

For detailed instructions for planting your dahlia tubers, be sure to check out my detailed post: “A Beginner’s Step By Step Guide For Planting Dahlia Tubers.”

How Deep To Plant Dahlias

Once it is time to plant your dahlia tubers, begin by finding dry areas with good water drainage. Start by a planting hole that is 4-6 inches deep. Next, place your dahlia tuber on it’s side with the eye of the dahlia tuber facing up. Gently cover up the dahlia tuber so it has 4-6 inches of soil covering it. Now the waiting game begins. Some dahlia tubers can take as long as 4 weeks before you see sprouts above the ground.

Spacing Dahlia Tubers: How Far Apart To Plant Dahlias

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.

Dahlias Need Water: How Often To Water Dahlias

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.

Water Dahlias Once They Have Their First Set of True Leaves

Once your dahlias 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. During hot periods I will water my dahlias daily, checking to make sure the soil is not too wet. You do not want your dahlia tubers to rot.

Support Your Dahlia Plants: How To Stake Dahlias

With large blooms, tall dahlia plants can become top heavy and need to be staked. If you are just growing a few dahlia plants in your garden, you can either use garden stakes or tomato plant cages to support your dahlia plants.

If you are growing rows of dahlias, then you will want to use posts to corral your dahlias. I use t-posts spaced every 10’. Then, I use heavy duty polypropylene twine wrapped around the t-posts to support my dahlia plants.

How To Pinch Dahlias

After your plants start growing, you will eventually need to pinch your dahlias. Pinching your dahlias will encourage the plant to branch out and produce more stems. It is important to note that pinching dahlias can delay blooms by a couple weeks, but in the long run you will be rewarded with more blooms.

Knowing When To Pinch Dahlias

When your dahlia plants reach 12-18 inches in height (or have 4 pairs of leaves), you will want to pWhen your dahlia plants reach 12-18 inches in height (or have 4 pairs of leaves), you will want to pinch your dahlia plant.Find the center stem and cut out about 3-4’’ of the center stem. Your dahlia plant should have at least 4 sets of leaves at this point, so when you make the cut, you should be left with at least 3 sets remaining. By cutting out the center stem, you will encourage the plant to branch out and grow more side buds. Pinching is a good guideline if you also want your beautiful flowers to grow longer stems.

Weed Control

It is important to stay on top of weeds around your dahlias. You want the area below your dahlia plants to remain clear to prevent any pests and disease from affecting your plants. To avoid injuring your dahlia plants, hand pull or gently weed around your dahlias.

Diseases and Pests That Can Affect Dahlias

There are many diseases and pests that can affect your dahlias ability to grow. Keeping your dahlias weeded, watered, and fertilized can all help your plant to stay healthy and ward off pests and disease.

Slugs and earwigs LOVE dahlias. There are different ways you can keep both away and prevent them from devouring your beautiful plants! After planting you can put down Sluggo or SluggoPlus around your dahlia plants. This will need to be reapplied throughout the growing season.

Combating Pests and Diseases When Growing Dahlias

Powdery mildew is also something that can easily affect your dahlia plants. Powdery mildew is a fungus that can be treated with neem oil, a fungicide. Neem oil is used as both a fungicide and pest control. You can spray your plants every 7-14 days with neem oil to combat powdery mildew, spider mites, and aphids.

Applying Neem Oil To Your Dahlia Plants

Make sure that you do not spray neem oil when the bees are active. While a great, natural pesticide, neem oil is toxic to bees. Some gardeners prefer to spray their plants with compost tea. A good compost tea can help you grow stronger and healthier plants that are more disease resistant. Compost tea can also help to improve your soil’s fertility.

Beneficial Insects for Pest Control

See Also

How to Grow Dahlias | MiracleGro

Releasing beneficial insects is another way you can combat pests in the garden. I love to release ladybugs several times during the growing season. Lady bugs devour aphids and are a great, natural pest control solution.

Do I Need To Deadhead Dahlias

If you want to be rewarded with lots of dahlia flowers, you will want to deadhead your dahlias. Deadheading spent blooms will encourage new growth on your dahlia plants. To deadhead your dahlias, simply cut off the spent blooms.

How Long Do Dahlias Bloom

Once planted in the ground, dahlias take typically about 8 weeks to start blooming. For most growing zones in the U.S., you will typically see your dahlias start to bloom in July. Your dahlias will continue to bloom until your first hard killing frost.

Growing Dahlias As Cut Flowers In Bouquets

Dahlia flowers are exceptionally gorgeous in bouquets! Many people grow dahlias in their cut flower garden to fill their homes with fresh cut dahlias in the summer. While dahlias are a gorgeous cut flower, they do not have a very long vase life. With proper conditioning though, you can expect a vase life of 3-7 days for your dahlias.

When to harvest your dahlia flowers

When harvesting dahlia flowers, be sure to cut the flowers in the early morning or late evening. Start with a clean pair of garden shears to make your cuts. I like to bring a cool bucket of water into the garden with me so I can immediately place my dahlias in water.

After harvesting, boil a pot of hot water. Make a fresh horizontal cut in your dahlia stem and dip your stems in hot water (water should no longer be boiling, but still hot). Dahlias have a hollow stem and this will help your dahlias to start drinking water and hopefully prolong their vase life. If possible, place dahlias in a cool location for 12-24 hours to rehydrate (do not place in a fridge with fruits and vegetables).

Keep Your Cut Dahlia Flowers Out Of Direct Sunlight

Dahlia flowers are extremely sensitive. While it can be tempting to display your beautiful dahlia blooms in the kitchen, keep your dahlia bouquet away from direct sunlight and fruits and vegetables. Your bouquet will also benefit from fresh water, change out your water daily for longer vase life.

Do Dahlias Come Back Every Year

Depending upon your growing zone, dahlias may come back every year. In zones 8-10 you can actually leave your tubers in the ground over winter. Below zone 8, it is recommended that you remove your tubers from the ground to protect them from freezing and rotting over winter.

Even if you live in growing zones 8-10, it is recommended that you dig up your dahlia tubers every few years to divide the tubers.

When To Dig Up Dahlia Tubers

Dahlias can be a tender perennial in certain growing zones. In a colder climate, you will know when it is time to dig up your dahlia tubers. In late fall, once you’ve either had your first frost OR your dahlia tubers have been in the ground for at least 120 days, you can safely take them out of the ground. You will know when you’ve had a killing frost because you will sadly go out into the garden and your dahlia plants and flowers will all be black.

For detailed instructions on removing your dahlias, check out my blog post: “Everything You Need To Know to Successfully Store Your Dahlias Over Winter.”

How To Clean Dahlia Tubers For Storage

Before you can divide or store dahlia tubers, you need to clean them first. This is a messy process. I suggest wearing clothes that are waterproof and that you don’t mind getting wet. To begin, I like to also wear a waterproof pair of heavy duty gloves. You will need a hose and a good hose nozzle to spray off the dahlias. Be careful not to spray at too high of a setting as you can break or damage the tubers. Watch my YouTube video below to see how I clean my dahlia tubers.

Multiply Your Tuber Stock: How To Divide Dahlia Tubers

Dahlia tubers are expensive. One of the best ways to multiply your stock is to dig up your tubers at the end of the growing season and divide them. One healthy dahlia plant will typically give you anywhere from 5-20 new tubers for the following season! Just imagine how many dahlias you can grow the following season if you divide your tubers!

To begin the process, I like to start by dividing my tuber clump in half. This allows me to get in and divide the tuber clump into individual tubers. To see this process, be sure to watch the YouTube video below as I show you how I divide a clump of tubers.

Growing Dahlias: How To Store Dahlia Tubers Over Winter

You can store dahlia tubers over winter either divided or in clumps. Once your dahlia tubers are clean and dry, it’s time to put them in your storage containers. I line plastic bins with about 2” of vermiculite. (Some people prefer to store their dahlia tubers in peat moss). Then I place my tubers in the container (with the eye side facing up). Once you have a layer full, cover it in vermiculite and repeat. Your plastic bins should be stored in an area that has temperatures between 40-50 degrees. These steps are important as you do not want your tubers to freeze.

Periodically check your dahlia tubers for signs of rot

You should periodically check on your dahlia tubers over the winter. When you do inspect your tubers, check for any signs of mold or rot. If you find any, immediately remove those tubers from the container.

Join Your Local Dahlia Society

If you want to get more involved or learn more about growing dahlias, I recommend that you join your local Dahlia Society. The American Dahlia Society website has a list of various dahlia groups throughout all parts of the country. There’s lots of great reading material on their site that can help you to become a dahlia expert. You can also find and learn about new dahlia cultivars through the American Dahlia Society.

It’s Time To Start Growing Dahlias!

Well, I hope that after reading this far you feel inspired and motivated to grow your own dahlias! If you do decide to grow dahlias, I’d love to hear how it goes. Below you’ll also find a FREE printable step by step beginner’s guide to dahlias that I’ve created to help you plant your dahlia tubers. Soon you’ll discover that there’s nothing better than having fresh cut dahlia flowers from your own garden in the summer.

If you found this beginner’s guide to dahlias helpful, I’d also love to hear from you in the comments below. And don’t forget to PIN any of these images to Pinterest. Thanks for reading and happy gardening!

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