Propagating Dahlia Tubers: How To Start and Propagate Dahlia Flowers

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It’s hard to find a plant that appeals to everyone, but the dahlia does its best to provide something for everybody.

From its 42 species to over 57,000 registered cultivars and counting, the sheer range of shapes, sizes, and colors is so complex that enthusiasts are still trying to find a way to sort them all out.

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The good news is that once you find a species or cultivar you love, it’s easy to fill your entire home or garden with them.

Whether growing dahlias in a container or in the ground, propagation is quite easy and can fit seamlessly into your care routines.

How to Propagate Dahlia Bulbs and Tubers?

No matter which dahlia you have, you can propagate via division, stem cuttings, and seeds.

However, the process means one method may suit you better than another.

Propagating Through Division

The method of choice for those who need to overwinter their dahlias indoors or have container specimens, root division is an excellent way to clone a plant in the spring.

Prior to planting (or during repotting), take a look at the root mass for your dahlia.

Many growers prefer to remove the mother tuber and discard it, as it won’t produce as well after the first year.

Go through the roots, looking for tubers that have thin necks or signs of damage or disease.

Cut these away with sharp, sterile shears.

With the remaining tubers, look for swollen eyes (these can be made to sprout if you place them in a warm, moist environment for about a week, making them easier to spot). Learn tips on why Dahlias do not sprout.

These are the tubers you want.

Separate and plant each one in its own spot for the growing season.

Propagating Through Stem Cuttings

This method is actually an offshoot of dividing (no puns intended).

Instead of taking cuttings from the adult plant, you’re actually harvesting the sprouts from tubers you’re overwintering.

Choose the healthiest, firmest tubers around late January or February and set them aside in a warm spot.

Take a plastic planting tray or some pots around 6” inches deep and fill with an equal mix of moss and coarse sand.

If planting in a tray, space the tubers 4″ to 6” inches apart, and in all cases plant them so the stems are 1″ to 2″ inches above the soil.

Place the tray in a warm spot with bright, indirect light or fluorescent lighting.

Keep the soil slightly moist and eyes will appear after anywhere from 7 days to a month.

When the shoots from these eyes have four leaves, it’s time to harvest.

Using a sharp, sterile knife, try cutting just below the new stem so you get a bit of the tuber as well.

This will help the plantlet root faster.

You may also wish to dip the tuber slice in rooting hormone.

Removing the bottom pair of leaves, plant the stem in a container filled with a blend of potting mix and perlite.

You may wish to place an open Ziplock bag over the plant to form a humidity tent while it roots.

Rooting generally takes around 2 weeks, and you’ll know if the plantlet’s ready if it gives resistance when you give it a gentle tug.

Learn what to do when Dahlia plants will not flower.

Propagating Through Seeds

A word of warning: Don’t use this method if you have a dahlia cultivar because there’s no telling what will grow from the seeds!

If you have an actual dahlia species or are feeling brave, read on.

Fill a starter pot or seed tray with either a seedling potting mix or a blend of soil and perlite or vermiculite.

After lightly dampening the soil, poke holes about ½” inch deep and spaced 1” inch apart.

Sow the seeds and gently cover with the soil.

Water daily, keeping the container in bright, indirect light or under a grow lamp.

The seeds should germinate in about 2 weeks, and slightly faster if you’re using a seed mat.

If growing in a single container, you’ll want to separate them into their own pots once the seedlings reach 2″ to 3” inches tall or when the leaves begin to touch.

Gradually introduce the seedlings to the outdoors if planting in a garden, bringing them outside for longer and longer periods over the course of a week or so to acclimatize them.

You may also wish to pinch off the central growth bud on taller plants when they reach 12” to 18” inches tall to encourage fuller, bushier growth.

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