How do you plant dahlias? And when should you start?

Dahlias are incredibly popular! They’re striking, large, and colorful flowers that are sure to catch your eye in the garden! But how do you plant dahlias?

For many people, this still doesn't seem all that easy. That's why we've put together all our tips for planting dahlias.

Dahlia: Location and Care

The best spot for dahlias is a warm spot in the garden, in full sun. Dahlias thrive in well-drained soil that’s rich in nutrients. During the growing season, they like to be watered generously (especially if they’re in pots!). You can also give these plants a little liquid fertilizer each week during their long blooming period. They’ll reward you with an especially abundant bloom!

In the winter, you should dig up dahlias after the first frost. By then, the foliage will have turned black or brown. You can leave dahlias in the ground over winter only if they’re in a sheltered spot, in very well-drained soil that doesn’t get or stay too wet in winter, and covered with a thick layer of mulch. Even so, there’s always a risk of loss.

When Should You Plant Dahlias?

Once there’s no longer a significant risk of (night) frost, you can plant dahlias in the ground. This can be done from around mid-April through mid-May. Within a few weeks, you’ll see them sprouting above ground, and starting in the summer, you can enjoy their abundant blooms.

Starting Dahlias in Pots

Would you like to enjoy your dahlias even earlier? Then you can also start growing your dahlias in pots earlier. By starting them off in pots in early March, you can sometimes have blooms as early as mid-June. In case of frost or night frost, place the plants in a frost-free spot. You can also more easily place the pots in a spot where you have fewer (or no) problems with snails.

Once the dahlias are big enough, you can still plant them in the ground, or (if you’ve planted them in large pots) place them, pot and all, in the flower bed.

How to Plant Dahlias?

Select the dahlias you want to plant (from your winter supply or new dahlias) and dig a fairly spacious planting hole, based on the size of the tubers. Add some compost or good planting soil to the planting hole. Plant the tubers so that the top is about 5–10 cm deep.

If you want to try leaving your dahlias in the ground over winter, plant them a little deeper. Cover the dahlias with fresh, nutrient-rich soil and water them generously. This will wake the dahlia tubers and stimulate growth. Within 2–3 weeks, you’ll likely see growth points emerging above the ground.

By Ellywa – Own work, CC BY-SA 4.0

Can you grow dahlias in a pot?

While you typically start dahlias in pots and later transplant them into the ground, it’s also possible to keep dahlias in a pot. Choose a spacious pot (depending on the type of dahlia, a pot with a diameter of 30–40 cm is definitely recommended). Place the pot in a warm, sunny spot. Add a thick layer of hydro granules or pottery shards to the bottom of the pot to ensure good drainage. Fill the pot with nutrient-rich potting soil and, if desired, cover the dahlia with fresh compost. You can also add a layer of fine gravel as a top dressing. Water thoroughly after planting and repeat this 1–2 times a week until growth is visible. From that point on, water thoroughly every day.

After a few weeks, it becomes important to fertilize the dahlia once a week. Liquid plant fertilizer works very well for this. For example, fertilizer for potted plants or tomato fertilizer.

Note: Snails love young dahlias!

Once the young growth points emerge above the ground, they’re a real magnet for snails! Protect your young dahlias from snails and slugs as much as possible. For example, use a layer of sharp gravel, eggshells, sharp pinecones, seashells, or a copper border. Another effective way to deter snails is to start your dahlias in pots first. Once the dahlias are a bit larger (and the leaves are less young and fresh), you’ll have much fewer problems with snails.