Starting Dahlias in Pots

Get a head start on the growing season by starting dahlias in pots. With these step-by-step planting and growing tips, you will have beautiful blooms all season long!

Dahlias are the best cutting flowers because they produce many flowers from late summer through fall. To get dahlia blooms earlier, pre-sprout the tubers with my technique.

How to Start Dahlia Tubers Early

The process of starting dahlia tubers early in the season is quite simple. Fill pots with a bit of organic potting mix, and add the tuber, leaving the necks of the tubers just above the top of the soil.

Mist with water to lightly dampen the soil, place in a warm area, and wait. After a couple of weeks, the young plants will have several leaves and be ready to harden off outside after all danger of frost has passed.

Pre Sprouting Dahlia in Pots — Dahlia tubers ready to be planted

What to Do With Dahlia Tubers in Spring

With the arrival of early spring comes the arrival of dahlia tubers in the mail. When you receive your order of dahlia tubers, you may wonder what to do with dahlia tubers in spring?

Maybe you have some tubers in winter storage and want to know what to do with them?

You have three options–keep them in storage in the plastic bag they arrived in, wait until the cold soil in the ground warms and plant them outside or get a head start on the season by starting dahlias in pots indoors.

Pre Sprouting Dahlia Tubers in Pots

Dahlia plants are not frost-hardy, meaning they should not be planted outside until the soil temperatures warm to 60 degrees.

Pre-sprouting dahlia tubers by planting them in pots indoors is a great way to start your plants earlier in the spring.

Here in Missouri, zone 6, our last chance of frost date is April 22. Dahlia tubers are pretty particular about their needs for growth, and there are two things they love – a sunny spot to grow and warmth.

In parts of the country, as here in Missouri, we are experiencing an exceptionally cool spring. It’s the tail end of May, and we still have had overnight temperatures in the 40s for about a week now.

We’ve had almost no sun, and it’s rained every day- not ideal when planting dahlia tubers in the ground.

I am grateful to have dahlia tubers tucked away in the garden shed where they are happily sprouting.

Hopefully, mother nature will cooperate, and all the dahlias will be in the flower garden here in a couple of weeks.

Why You Should Start Dahlia Tubers Early

If you’re toying with starting dahlia tubers in pots to get earlier blooms, the time is nigh! Here are some reasons why you should start your dahlia tubers early.

Viable Tubers

Pre-sprouting dahlia tubers are a great way to test that your tuber is viable. If you are unsure that your tuber has an eye, then pre-sprouting is the best way to give the dahlia a chance to show it is a viable tuber before being planted in the garden.

Soil Warmth

Dahlias grow best in warm weather. The soil should be around 60 degrees Fahrenheit before placing the plant outside in the ground. The soil in pots will warm much more quickly than the soil in the ground.

For pre-sprouting the dahlia tubers, place the potted tuber in a sunny, south-facing window to keep the soil warm. Or, if necessary, place the pot on a seed-warming mat to keep the soil warm.

Get a Jump on the Flower Growing Season

One of the best reasons for sprouting dahlia tubers early in pots is to get a head start on the growing season. Dahlias are one of the easiest cut garden flowers to start indoors in pots.

I am always looking for a flower gardening project –especially after a long winter. One of my all-time favorite things to do is start my dahlia tubers in pots! Sprouting your tubers will help them develop strong, healthy roots before being transplanted out into the garden.

When Should I Start Dahlias Indoors

The best time for potting up dahlia tubers for an early start to the growing season is in late March to early April if you hope to plant them by mid-May when the soil has warmed in most locations.

Dahlias typically take about two to four weeks to start sprouting out of the soil, which means you should start this process six to eight weeks before the expected planting time in your region.

Best Soil for Starting Dahlias in Pots

To start dahlia tubers in pots, it is best to use an organic potting mix blend, a loose blend of organic matter such as sphagnum peat moss, humus, & perlite. This blend is also enriched with earthworm castings, alfalfa meal, kelp meal & feather meal.

Whichever potting mix you pick, it should be loose dry, or wet. It’s essential to ensure no clay in the mix, as Dahlias do not grow well in heavy clay soil.

Gardening Essentials for Starting Dahlias in Pots

This post contains affiliate links; I make a tiny commission off any purchase that you may make. This small commission helps you keep Rocky Hedge Farm going at no additional cost. Please see my disclosure policy for more information.

Pots: depending on the size of the dahlia tuber, choose a pot to accommodate the tuber. Anything from 6″ plastic pots to gallon pots will work.
Organic Potting Mix: This organic mix for sprouting dahlia tubers is a rich blend of sphagnum peat moss, humus & perlite enriched with earthworm castings, alfalfa meal, kelp meal & feather meal
Heat Mat: this heat mat maintains sweet-spot temperatures around 68-86 degrees. It is wear-resistant and durable to use.
Dahlia Tubers: hopefully, you already have your dahlia tubers, but if you are looking to purchase healthy tubers that are good quality, here are some flower farmers to purchase from. Triple Wren Farms and Bear Creek Farm are both great options. You can also see more recommended dahlia sources at Floret Flowers.
Plant Labels: don’t forget to write the name of the variety of dahlia on a plant label so you can remember what was planted in each pot.
Plant Spritzer: this little plant spritzer is excellent for giving dahlia tubers just a bit of water at a time.

How to Start Dahlia Tubers

Starting dahlias in pots has several benefits. Getting the tubers out of storage and planted in pots helps the plants grow a healthy root system with plenty of leaves in time for planting in the garden.

But, my favorite reason for sprouting dahlia tubers is to get an early start on flower gardening. I love walking through the gardens in the early morning, gathering fresh-cut floral bouquets for our home all season long.

Growing Dahlias in Pots — Planting a Dahlia Tuber in a Pot

Plant Dahlia Tubers

Depending on the size of your dahlia tuber, plant a single tuber in a 6-inch-diameter pot or a larger tuber clump in a one gallon pot. The pot will need to have good drainage holes at the bottom.

Fill the bottom half of the pot with slightly moist potting soil. Lay the dahlia tuber either on its side or pointed upward on the soil with the neck of the tuber pointed up in the planting hole.

Sometimes, the tuber will already have a tiny sprout, and if so, go ahead and pot those tubers. It simply gives them a chance to grow strong before being planted in the ground.

Then, add another layer of potting mix. If the head and neck of the tuber are sticking out, this is perfectly fine. Or, you can choose to cover the entire tuber with 1-2″ of soil, either way, the tuber will sprout.

I like to leave the neck exposed to see the new growth that the tubers are beginning to put on.

Label the Dahlia Tubers

After planting the tuber in the pot, write the name of the variety on the container or a plant label.

This helps to remember what has been planted and how to label the plant once it is transplanted into the ground.

Watering Dahlia Tubers

Watering dahlia tubers depends very specifically on your soil conditions.

It isn’t essential to water dahlia tubers after they have been potted if the organic potting mix is moist. However, if the soil is dry, it is okay to lightly mist the soil to dampen it.

Once the first leaves appear, lightly water the plants, then water the soil sparingly whenever it feels nearly dry beneath the surface. Just keep in mind that too much water will cause tuber rot.

Keep the Tubers Warm

Dahlias sprout best when the soil temperature is above 60 degrees Fahrenheit. Place the potted dahlia tuber near a sunny window. The room temperature needs to stay warm all day and night.

If you don’t have a warm enough space, consider placing the pot on a seed warming mat to keep the soil warm.

Transition Tubers

Dahlias should be moved to the flower garden after the last spring frost has passed and the soil is at least 60°F.

It’s important to harden off or acclimate your dahlia outdoors before planting them in the ground.

This is best done by moving them into a shady location during the day and then bringing them back in during the night for a week.

After a week, leave them in a slightly sheltered location from the sun and strong winds all day and night. Then transfer the plants to the flower garden.

Plant Dahlias Out in the Garden

To plant the dahlias in the garden, choose a location with good drainage and full sun. Remove the tuber with the potting soil and place it in the ground.

Bury the crown of the tuber where the leaves are coming from several inches below the soil surface.

If you bury several of the leaves or shoots below the surface of the soil, this is okay.

They will continue to grow through the soil. If a shoot breaks during the planting process, don’t worry; another one will grow.

To give your dahlias the best start in the garden, follow my guide for planting dahlia tubers.

If you want more blooms on your dahlias, be sure to learn how to pinch out dahlias! And, for maximum size blooms, disbud the dahlias!