start dahlias early in pots to get ahead of the season

Get an Early Start on Dahlias With Pots

by | Mar 18, 2022

Sure, it’s a little more work to start dahlias early, but these flowers are worth it! This little potting up technique I’m sharing today is a great way to get a head start on the season and makes sense for gardeners who are trying to use their space intensively too. The more I venture into growing dahlias, the more I struggle to find space! Sound familiar?

Why would I start dahlias early?

There are multiple reasons you might want to pot-up and start your dahlia tubers early.  One such reason is: space. As someone who loves growing alllll the things and constantly agonizes over how much space to give flowers versus vegetables, starting my dahlia tubers in pots allows me to intensively grow in one space, while always having plants ready to be transplanted. Let’s use this one garden bed, pictured below, as an example.

This year, I have allotted this bed as one of my few flower beds. Currently, it’s growing ranunculus and anemones flowers that are just about to bloom, but those flowers will also need to die back a bit before I dig up the corms. In other words, it’s going to be a while before dahlias can be planted here.

spring bed of colorful ranunculus and anemone flowers

This is a designated “flower” bed that is currently filled with blooming ranunculus and anemones. Since my dahlia tubers cannot be planted yet, I decided to start my dahlias early in one gallon pots.

Here in Southern California it is now safe to plant dahlia tubers out in the ground but, because of the ranunculus in my garden space, I can’t! Furthermore, if I wait until the ranunculus are done to plant out my dahlia tubers, the dahlias will be extremely behind in the growing season and flowers will be far off in the future—and that’s where potting up dahlia tubers in pots benefits me! Maybe you too?

If that example doesn’t apply to you, another reason to start dahlias early in pots is to get ahead of the growing season in colder climates. While it does take extra work and pampering, you can start dahlia tubers in pots, in Early Spring, indoors (or in a greenhouse). By doing this, your dahlia tubers can sprout, grow a strong root system, and grow before ever being transplanted into the garden! Remember though,  Dahlias do not fare well in frost, so the goal is to keep them warm and provide enough light once they have sprouted.

Due to my own climate, I can keep my potted-up dahlia tubers in a corner of my garden next to a fence and rock wall, where it stays warm. If we have a frosty night expected (temperatures in the 30s) I even cover my dahlia pots with row cover or other overturned pots for the night.

cafe au lait dahlia growing in a raised garden bed

These were my ‘cafe au lait’ dahlias growing in my raised garden bed. In the winter, it became difficult to plant around the tubers. In the Summers they started to take up a whole half of my raised bed! This is why they had to be dug up and moved to a designated flower bed.

Last year I decided my cafe au lait dahlias, that were growing in my raised vegetable beds, were taking up too much space. I dug up the tubers after the Summer passed and left them in a grow bag in my garage. Full disclosure, that is not a recommended way to store dahlia tubers over winter, but I’m a very lazy gardener and the tuber clump was so large I didn’t have another storage option. Eventually, that tuber clump started to dry out, so I planted it in a grow bag just like I outline below. Now, there’s a pretty good plant growing in the grow bag! I’m concluding that digging up tubers and transferring them to pots or grow bags filled with potting soil in Winter is probably a good way to go for those in mild climates that need the space.

How to start dahlias early in pots

The process is surprisingly simple and straight forward. You will need:

♦dahlia tubers (view seed and tuber sources I’ve used HERE)

♦1 gallon pots (we always save our pots from purchases so we have many in our garden shed)

♦organic potting soil

a large dahlia tuber clump that is already sprouting

This is a new dahlia tuber, and you can see that it already started sprouting! It’s ready to grow! Starting dahlias early in pots makes it easier for me to work within my smaller garden space and plant intensively.

How to Pot Up Dahlia Tubers To Get an Early Start

Hopefully your tubers will fit in one gallon pots! Most of mine were new tubers, so they all fit, with the exception of the cafe au lait—that one got a grow bag all to itself.

Place a little soil in the bottom of your pot and place your tuber inside to see where the eye of the dahlia tuber sits. In Tips for Magnificent Dahlias, I go over a little dahlia anatomy, but the “eye” is basically the little spot at the top of the tuber where sprouts will form. I planted my eyes about 2-3 inches deep.

Once you’ve gotten the correct height, simply fill around the tuber with your potting soil. I’ve been using G & B Organics potting mix recently, but any good potting mix will do.

place dahlia tubers in pots filled with potting mix to start them sprouting early

This gallon pot is filled on the bottom with potting mix, and I placed the tuber so that the little eye (which you can see sprouting) will end up about 1-2 inches below the soil line. That’s all you need to start dahlias early!

One important thing to note is dahlia tuber shape. Dahlia tubers come in a variety of shapes and sizes and clumps. In my example photo, that is a clump of tubers that I planted. If your tubers are singular or on the longer side, you can lay the tuber on its side with an eye facing upwards before burying.

Watering After Planting Tubers

One common question is: should I water my dahlia tubers upon planting? I’m beginning to suspect this is a climate/zone specific question. Personally, Southern California is just so warm during the Winter—borderline scorching some days—-so the risk of rot is pretty low and I don’t want my tubers to dry out completely. Therefore, I do water my dahlia tubers slightly after planting and continue to monitor throughout the season.

Once your dahlia tubers have started to sprout, definitely keep the soil moist and the plants safe from frost in a warm environment. And that’s how you can start dahlias early in pots!

Other Applications of this Method

Besides dahlias, I’ve recently learned that this can be done with bare root roses too. One reader shared over on Tips for Getting Started Growing Roses that they plant their bare roots in pots to get a head start on the season. Coincidentally, I was expecting a shipment of bare root roses from David Austin Roses but didn’t have the garden area ready yet, so I tried out this technique! The bare root roses leafed out wonderfully in 5 gallon pots.

You can also pot up ranunculus and anemone corms early as well! I haven’t personally tried this, but have seen many gardeners do it. Honestly, this could probably be applied to a wide variety of plants!

dahlias can be started early in gallon pots with potting mix

Here is a selection of my dahlia tubers started early in pots. You can see that some have sprouted and I’m still waiting on others.

Planting Dahlias in the Garden

There’s quite a bit of dahlia growing information here on Freckled Californian. I’ve shared how to plant and care for dahlia tubers in Tips for Growing Magnificent Dahlias and journaled about my experience Growing Dahlia Flowers From Seed. The adventures will continue!

Meanwhile, once the ranunculus and anemones are done for the season, I’ll amend the soil organically with some compost, bone meal, and an all-purpose fertilizer. My process for amending soil can be found HERE, but it also varies depending on what’s available and what I’m planting.  Once the garden bed is ready, I’ll plant these dahlias just like I transplanted my dahlia seedlings or any plants really. There won’t be a need for a row cover because it is already plenty warm here in Southern California! Hope you all have a wonderful, dahlia-filled Summer!

Meet Randi

Urban gardening is my jam. I’m Randi, California girl who obsessively gardens to grow food and flowers around my urban home. Seasonal, simple living is what inspires me~ I hope it will inspire you too. Join me in crafting a life and home connected to the garden Read More>>>>

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