How to Grow Dahlias for Summer Color

Updated on February 2, 2020
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.


Growing up, my mother grew flowers and my father grew vegetables. The only exception to this division of labor was my father’s dahlias. He loved them, especially the large dinner plate dahlias. There was even an informal neighborhood competition to see who could grow dinner plate dahlias with the biggest flowers.

What are Dahlias?

Dahlias (Dahlia pinnata) are flowering plants that grow from underground tubers. They are related to sunflowers, chrysanthemums and zinnias. Dahlias are originally from Mexico so they are not cold hardy. North of zone 8, they are grown as annuals or the tubers are lifted from the garden and stored indoors until the following spring.

A modern single dahlia which resembles its ancestors
A modern single dahlia which resembles its ancestors | Source

Dahlias were cultivated by the Aztecs for their tubers which were eaten rather than for their flowers which were small and daisy-like. The plants made their way to Europe in the 16th century after the Spanish colonization of the New World. Starting in the late 17th century, European hybridizers began developing the different flower forms with which we are familiar today. They are the single flowered dahlias, which resemble their ancestors, the pompom dahlias, the cactus dahlias with their spikey petals, decorative dahlias which resemble chrysanthemums and the enormous dinner plate dahlias whose flowers can be as large as 12 inches across. Within those flower forms, there are 14 recognized groups of flower types.

A decorative dahlia.  It looks very much like its cousin the chrysanthemum.
A decorative dahlia. It looks very much like its cousin the chrysanthemum. | Source

How to Grow Dahlias

Unless you buy plants, what you will receive when you purchase dahlias are brown tubers that resemble carrots. The tubers should be planted in the spring when the soil reaches 60⁰F. You can also start your tubers indoors 4 to 6 weeks before your last frost. Plant them in individual containers 3 inches below the top of the soil. You should insert a stake in the container to support the plant as it grows. Depending on the variety, the plants can grow 3 to 6 feet tall.

In the garden, select a site that gets full sun and has protection from the wind. Plant the tubers 6 to 8 inches deep. Smaller dahlias should be planted 2 feet apart while the larger ones should be planted 3 feet apart. Plant the tubers like carrots with the pointy end downwards and the fatter end which has the growth tip pointing upwards and level with the top of the soil. You should also install support stakes at planting time so that you don’t damage the tubers later in the season trying to push the stakes into the ground. The stakes should be 5 to 6 feet tall. Tie the stems to the stakes as they grow.

Do not water the tubers after planting. This will cause them to rot. Wait until you see the plants emerging from the soil and then give them a good soaking. Thereafter you can water 2 or 3 times a week to keep the soil moist.

Pompom dahlias.  They remind me of golf balls.
Pompom dahlias. They remind me of golf balls. | Source

How to Grow the Biggest Dahlia Flowers

Dahlias will start flowering 8 weeks after planting, usually in July. They should be deadheaded regularly to ensure continuous blooms until the plants are killed by frost in the fall. To encourage dinner plate dahlias to produce their large flowers, they should be disbudded. All dahlias send up a stalk with a terminal bud on the end and other buds along the sides of the stalks. All of these buds will open into flowers. If you want large flowers on your dinner plate dahlias, you should remove all of the side buds so that the plants will concentrate all of their energy into the single terminal bud. This is known as “disbudding”. Unfortunately it means that you will only have one flower per plant if you want the largest flowers.

Cactus Dahlias.  Cactus flowered zinnias are nearly identical.  Not surprising because zinnias are in the same family as dahlias.
Cactus Dahlias. Cactus flowered zinnias are nearly identical. Not surprising because zinnias are in the same family as dahlias. | Source

How to Store Dahlia Tubers

In the fall, the frost will kill the plants but don’t dig the tubers up immediately. Wait for a week after the foliage dies. This allows the tubers to achieve full dormancy for the winter. Gently dig up the tubers then cut away the foliage. Brush the soil from them but don’t wash them. Wetting them at this stage will cause them to rot over the winter. Allow the tubers to air dry for 24 hours.

Line a cardboard box with newspaper and put the tubers in the box in a single layer. Cover them with sand, sawdust or peat moss that is slightly moist. Store the box in a cool dark place that remains 40⁰F to 50⁰F all winter. Check your tubers regularly. If they start to shrivel, mist the packing material very lightly.

And don’t forget your labels! If you are growing more than one type of dahlia, label each variety. No matter which variety you are growing, the tubers all look alike.

In the spring when the soil has warmed, remove your tubers from their winter quarters. This is a good time to divide them if they had grown into large clumps last summer. Using a sharp knife, cut the clumps of tubers into smaller groups leaving at least 3 “eyes” in each clump. The plants grow from those eyes just like potatoes do. Then plant them in your garden after the soil has warmed.

© 2018 Caren White


    0 of 8192 characters used
    Post Comment
    • OldRoses profile imageAUTHOR

      Caren White 

      12 months ago

      I'm so glad that you found it helpful!

    • Gloriousconfusion profile image

      Diana Grant 

      12 months ago from United Kingdom

      I've just bought a dahlia with dark purple foliage still at the budding stage, so I'm waiting to see what it looks like. I wasn't sure whether it needed full sun, and whether it would grow well in a large pot, so finding your article today was very helpful and I shall follow your advice, thanks.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)