Dahlias have become one of my favorite flowers to grow! They are beautiful and diverse, and each carries its own unique charm. They are truly a spectacle in the garden and make such gorgeous flower arrangements in the home!

Over the years, I've planted many dahlias in my garden, and though I'm no expert, I'm excited to share what I've learned with you so you can have beautiful blooms too!

Growing dahlias may not be the easiest compared to other cut flowers, but they are definitely worth it. And once you have figured out all the ins and outs, you will not regret it.

Scroll down to learn more and let's start growing dahlias together this summer!

Contents:

Understanding tubers & clumps
When to plant dahlias
Where to plant dahlias
How to plant dahlias
Growing dahlias in containers
How to grow dahlias from seed
What to do after planting
Digging up dahlia tubers

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Understanding Tubers & Clumps

Dahlia tubers are like the heartbeat of these stunning flowers. They consist of a stubby stem with several swollen parts attached, meeting at what we call the crown. Tubers are similar to a potato. From this crown, stems sprout from buds, or eyes.

These eyes are where the magic happens, as they are the starting point for dahlia stems to grow. It's essential to note that tubers serve as food storage vessels to fuel the plant's early growth, but they themselves don't sprout.

The tubers will multiply yearly, but you only need one tuber with one "eye" to successfully grow a vigorous dahlia plant. And when you dig up the tubers in the fall (more on this later), store them correctly, and divide them, you can easily triple or quadruple your stock in 1 year.

A clump, on the other hand, is a cluster of tubers around a stem, which can make planting slightly different from planting individual tubers.

When to Plant Dahlias

Timing is crucial when it comes to planting dahlias, as they do not like cold soil.

Aim to plant your tubers when the ground has warmed up (when the soil reaches 60ºF) in spring, and there's no threat of frost. This is usually around May, depending on where you live.

A good rule of thumb is to plant them around the same time you would plant tomatoes.

Alternatively, you can start them in pots about a month before the last frost and then transplant them once the danger of frost has passed. This will give you a bit of a head start, meaning you can expect some flowers earlier!

Where to Plant Dahlias

Dahlias thrive in full sun, so choose a planting site that receives at least 6 to 8 hours of direct sunlight daily. Morning sunlight is particularly beneficial for them.

It is also good to plant them where they are a bit protected from the wind, although mine don't have some sort of cover near them, and they are doing great.

Opt for fertile, well-drained soil with a pH of 6.0 to 7.5. Raised beds have worked wonders for my dahlias, providing both good drainage and a fertile environment for growth.

Read more: Raised beds vs. in-ground beds

How to Plant Dahlias

Planting and growing dahlias is relatively straightforward but requires attention to detail.

Here's a step-by-step guide:

Digging the Hole: Start digging a hole about 6 to 8 inches deep.
Preparing the Soil: Mix some compost and a handful of bonemeal into the planting hole to provide essential nutrients for your dahlias.
Positioning the Tubers: Place the tuber in the hole with the eyes facing upward. If you are unsure about which end is up or if the tuber has eyes, plant it on its side. When planting clumps, position them with the stem up and tubers down. Space the larger varieties 3 feet apart, medium-to-low-height varieties 2 feet apart, and the smallest bedding dahlias, grown from seed, 9 to 12 inches apart.
Covering with Soil: Cover the tuber with 2 to 3 inches of soil, ensuring the sprouts are at ground level.
Watering: Resist the urge to water immediately after planting, which can encourage rot. Wait until the sprouts have emerged above the soil before watering.
Staking: Tall, large-flowered dahlias may require support. Install stakes around the plants and tie the stems as they grow.

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growing dahlias in containers

Medium—to dwarf-size dahlias can be grown successfully in pots, making them a versatile option if you have limited space or want to add a pop of color to your patio or balcony.

Here’s how you can grow dahlias in containers or pots:

Selecting the Right Pot: Choose a pot at least 12 inches in diameter with drainage holes at the bottom to prevent waterlogging. Larger pots provide more space for root growth and stability for the plant.
Potting Mix: Use a well-draining potting mix rich in organic matter. You can mix garden soil with compost or use a commercial potting mix formulated for flowers.
Planting: Plant the dahlia tuber in the pot with the eyes facing upward, similar to how you would plant them in the ground. Ensure the tuber is covered with a few inches of soil, leaving the sprouts at ground level.
Watering: Hold back on watering for now, as this will only cause root rot. You just want slightly damp soil. Once the plant has started to sprout, you can start watering. Allow the top inch of soil to dry out slightly between waterings to prevent root rot.
Sunlight: If growing indoors, place the pot in a location that receives full sun for at least 6 to 8 hours a day. Choose a bright, sunny spot near a south-facing window.
Support: Depending on the variety of dahlia and the size of the pot, you may need to provide support for the plant as it grows. Install stakes or a trellis in the pot to support the stems and prevent them from bending or breaking.
Fertilization: Dahlias grown in pots may require more frequent fertilization since nutrients can leach out of the soil faster. Use an organic fertilizer every 2 to 3 weeks during the growing season.
Maintenance: Regularly remove faded flowers (deadheading) to encourage continuous blooming. Monitor the plant for pests and diseases and address any issues promptly.

How To Grow Dahlias From Seed

Growing dahlias from seed can be a rewarding experience. However, it requires a bit more patience compared to growing them from tubers.

Here's a step-by-step guide on how to grow dahlias from seed:

Selecting Seeds: Choose high-quality dahlia seeds from a reputable supplier or harvest them from existing dahlia plants in your garden. If you're harvesting seeds, select mature seed heads from healthy plants at the end of the growing season.
Preparing the Soil: Fill seed trays or small pots with a well-draining potting mix. Moisten the soil slightly before planting to ensure good seed-to-soil contact.
Planting Seeds: Sow dahlia seeds thinly on the soil's surface about a week or two before your last frost date, spacing them about an inch apart. Press the seeds lightly into the soil but avoid burying them too deeply, as dahlia seeds require light to germinate.
Covering and Watering: Cover the seeds with a thin layer of fine soil or vermiculite to help retain moisture. Water the soil gently using a misting spray or a watering can with a fine rose attachment to avoid displacing the seeds.
Providing Warmth and Light: Place the seed trays or pots in a warm location with indirect sunlight. Ideally, the temperature should be around 70-75°F (21-24°C) to promote germination. You can also use a heating mat to maintain consistent warmth.
Germination: Dahlia seeds typically germinate within 7-14 days, although it may take longer for some varieties. Keep the soil consistently moist but not waterlogged during this period.
Hardening off: Before transplanting seedlings outdoors, gradually acclimate them to outdoor conditions by exposing them to increasing amounts of sunlight and outdoor temperatures over the course of a week.
Transplanting: Once the seedlings have developed 2-3 sets of true leaves, they are ready to be transplanted into larger pots or directly into the garden. Gently separate the seedlings, being careful not to damage the delicate roots.
Planting Outdoors: Choose a sunny location with well-drained soil for planting your dahlia seedlings. Space the plants according to their mature size, typically 12-18 inches apart.

Continue with after-planting care as you would for tubers. Flowers should appear about 10 weeks after sowing the seeds, depending on the weather.

Dahlias grown from seed yield tiny clumps of tubers that are often too small to divide, so you can preserve the entire bundle in a Ziploc bag packed with peat moss or vermiculite throughout the winter.

*If you live in a growing zone with a longer growth season, you can directly seed your dahlia seeds in the garden. Your soil must still be at least 65–70 degrees F.

What to Do After Planting

Have Patience, Friend. Sprouts may take up to five weeks to emerge, so be patient. You can expect blooms about 8 weeks after planting.
Once sprouted, dahlias benefit from a low-nitrogen, liquid fertilizer, or organic fertilizer like compost, which is applied every 3 to 4 weeks until early autumn.
When plants reach about 1 foot tall, pinch out 3 to 4 inches of the center branch to encourage bushier growth and more flowers! If you want single, big blooms, you do not need to pinch.
For larger flowers, consider disbudding by removing smaller buds next to the central one in a flower cluster.
The more you cut and remove faded flowers, the more they bloom!
To make a bouquet, cut stems in the morning before it gets too hot, and place them in a pail of cool water. Remove the stems' bottom leaves and set the flowers in a vase with water. Place the vase somewhere cool and away from direct sunlight. Check the water daily. They will stay fresh for up to around 7 days.

Digging Up Dahlia Tubers

Dahlias are native to Mexico, so they are not particularly winter-hardy and won't survive freezing temperatures. They will split in freezing temperatures and start to mold in soggy soil.

For this reason, you need to dig up your dahlia tubers and store them for the winter until spring, when all signs of frost have passed. If you live in a warm climate with no freezing temperatures, you can leave them in the ground.

In my zone, 7b, I have left tubers in the ground and they have grown back. We have raised beds which I think helps!

But don't worry, when stored properly, the same tubers can be replanted each spring and last you years!

Read this blog on how to store Dahlia tubers in winter.

Friend, growing dahlias can be a rewarding experience and the joy of picking a beautiful bunch to make an arrangement for your home is unmatched!

With the right care and attention, you'll be rewarded with a stunning display of blooms in your garden.

Love, Annette xx

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