There are three primary methods to learn how to grow dahlias: from tubers, rooted cuttings, or seeds.
Tubers are the underground storage organs of mature dahlias, resembling a cluster of brown, carrot-shaped roots connected by the dried stem of the previous season. You can purchase tubers in spring from local nurseries or online suppliers, or reuse the ones you stored through the winter.
About Dahlia
Choosing a favorite dahlia can feel like sorting through a box of colorful buttons! Their blooms range in size from small 2-inch pompom types to massive “dinner plate” varieties reaching up to 15 inches across. Most types grow between 4 and 5 feet in height. Dahlias are available in a stunning spectrum of shades: white, cream, yellow, orange, peach, soft pink, hot pink, crimson, deep red, lilac, violet, near-black, multicolor blends, bronze tones, fiery hues, and beautifully variegated or bicolored combinations.
Dahlias belong to the genus Dahlia in the Asteraceae (daisy) family. These tuberous perennials are typically planted outdoors in late spring around May and begin blooming from midsummer until the first frost in fall. They are Ideal for borders and also make excellent flowers for cutting. If you grow vegetables, consider planting a row of dahlias along the edge of your garden. They’ll brighten the space without casting shade on your crops.
When to Plant Dahlia Tubers
Starting dahlias in containers is an excellent method to kick-start their growth earlier in the year. Plant the tubers in spacious pots using a peat-free, all-purpose compost during March or early April. Place the containers on a sunny windowsill or inside a greenhouse protected from frost, and wait until late May. Once the risk of frost has gone, transplant them outdoors.
Potting up dahlias early also helps them establish faster, which often results in earlier blooms. To prepare for planting, soak the tubers in a bucket of lukewarm water for about an hour to allow them to rehydrate properly.
Growing Dahlias in Pots
Many types of dahlias thrive in pots throughout the year, adding vibrant color to patios and balconies. Compact and medium-height varieties such as mignon, ruff, ball, pompom, and water lily dahlias are particularly well-suited for container gardening. Avoid tall types like cactus dahlias, which can reach heights over 2 meters and typically need staking. As a general guideline for how to grow dahlias in containers, stick to those that maintain a manageable height.
Position potted dahlias in a bright, sunny, and sheltered location, away from harsh winds. Keep the soil moist and add a liquid fertilizer rich in phosphorus once a week to support healthy blooming.
Choose a free-draining, peat-free compost mix and plant the tubers halfway into the potting mix, ensuring the buds are just lightly covered with soil. Give them a good watering after planting. Once shoots reach around 10 cm tall, pinch out the tips to promote fuller, bushier plants.
What You’ll Need:
– Dahlia tubers
– Large containers
– Peat-free multi-purpose compost
– Plant tags
– A marker or pen
Step 1
When planting dahlia tubers, make sure the point where the roots connect to the old stem faces upward. Label each container clearly and place them in a greenhouse or on a bright windowsill. Keep the soil evenly moist to help the tubers establish.
Step 2
Once growth appears, pinch back the top of the central shoot just above the uppermost set of leaves. Also, thin out the new shoots by keeping only five strong ones and removing the rest. It will encourage the plant to grow fuller, with sturdier stems and a higher flower yield.
Step 3
After the danger of frost has gone, begin acclimating your dahlias to outdoor conditions. Set them outside during the day and bring them in at night for about a week. After this hardening-off period, they’ll be ready to settle in their permanent spots in the garden.
How to Care for Dahlias
Once fresh shoots begin to emerge on young dahlia plants, feed them with a potassium-rich fertilizer to support strong development and encourage an abundance of blooms.
At the end of autumn or the beginning of winter, dahlia tubers should be dug up and divided. Trim back any dying foliage as the season ends. Gently lift the clump of tubers and separate them, ensuring each piece has a visible growth “eye” to sprout from. Store the individual tubers in a cool, dry, and dark spot, such as a cardboard box filled with dry sawdust or shredded paper, until you’re ready to plant them again in spring.
In areas with very well-drained soil, you can opt to lift, divide, and immediately replant the tubers in early spring each year.
FAQs
Can you leave dahlias in pots over winter?
Yes, you can keep dahlias in containers through winter, but they’ll need protection from the cold. Trim back the plants and move the pots into a frost-free location like a shed or garage.
When do dahlias start to sprout?
Tubers planted in early spring usually show signs of growth within 2 to 3 weeks.
Are dahlias edible?
Yes, dahlia petals are edible if they are grown without pesticides. They make a beautiful, flavorful addition to fresh salads.
Can dahlias self-seed?
They can, but the new plants likely won’t match the original. You might discover unique and unexpected blooms from self-seeded dahlias.
Are dahlias toxic to pets?
Unfortunately, yes. Dahlias are toxic to cats and dogs, so it’s best to keep them out of reach if you have furry companions.
