How to Get an Early Start on Dahlias by Planting Tubers in Pots

It takes a little more work to start dahlias early, but the flowers are worth it! The potting up method I’m going to show you today is a great way to get a head start on the season and makes sense for gardeners who want to make the most of their space. The more I venture into growing dahlias, the more I struggle to find space! Sound familiar?.

Dahlias are beloved for their bright, showy blooms that come in a kaleidoscope of colors To get the longest flowering period from these beauties, many gardeners like to get a head start on the season by planting dahlia tubers in pots. This technique allows the tubers to sprout and grow strong roots before transplanting them into the garden later in spring Follow this complete guide to successfully start dahlia tubers indoors in containers.

Why Start Dahlias Early in Pots?

Getting a jump on the dahlia growing season by starting the tubers in pots offers several advantages:

  • Longer flowering period. Tubers sprouted ahead of planting time will bloom earlier and longer into fall.
  • Larger plants and blooms. More time to grow before summer heat means bigger, bushier plants.
  • Use garden space efficiently Start tubers while beds are still occupied by other plants.
  • Ideal for shorter growing zones. Warmer conditions indoors give tubers a head start.
  • Flexible planting timing. Transplant tubers anytime beds are ready, without rushing.

By getting your dahlia tubers actively growing 4-6 weeks prior to transplanting, you can maximize flowers in gardens with short seasons or limited space.

When to Start Dahlia Tubers in Pots

Time your potted tubers for transplanting according to your local climate:

  • Warm zones (no frost): March to April
  • Moderate zones (light frosts): February to March
  • Cooler zones (hard frosts): January to February

Ideally, tubers should be started 10-12 weeks before your average last spring frost date. Check tuber growth weekly to gauge transplant timing.

Choosing the Right Pot Size

Select a container that provides ample room for tuber growth but isn’t oversized. Recommended pot sizes:

  • Miniature dahlias: 1 gallon
  • Small singles/pompoms: 2-3 gallons
  • Medium dahlias: 5 gallons
  • Giant dahlias: 10 gallons

For long tubers, use wider, shallower pots. Avoid cramped pots, which can inhibit growth. Drainage holes are essential.

The Best Potting Mix for Dahlias

A quality potting soil is key for healthy tubers. Look for:

  • Light, fluffy texture to resist compaction.
  • Good drainage and aeration.
  • Low or no peat for sustainability.
  • Slow release fertilizer like fish emulsion or compost.
  • Neutral pH around 6.5-7.0.

Avoid heavy, dense soils or those with water retaining additives. Dahlias prefer a more porous mix.

How to Plant Dahlia Tubers in Pots

Follow these simple steps for potting up tubers:

  • Fill the container about 1/3 with moistened potting soil.
  • Nestle the tuber horizontally in the soil, eye end up, 2-3 inches deep.
  • Cover with soil to just below the tuber eye/sprout. Don’t bury sprouts if present.
  • Water well until soil is moist but not soaked.
  • Place in warm (65-70°F) spot with good light.
  • Pot up additional tubers, allowing 1-2 per small pot and 3-5 per large pot.
  • Let tubers sprout before transplanting!

Caring for Potted Dahlia Tubers

Once potted, dahlia tubers need attentive care:

  • Water whenever soil is partly dry to touch. Avoid excess moisture.
  • Move to sunny, frost-protected spot when sprouts appear.
  • Watch for pests like aphids, thrips, slugs. Remove by hand immediately.
  • Turn pots regularly so sprouts grow upright. Stake if needed.
  • Pinch out growing tips once 4 sets of leaves form for bushy plants.
  • Harden off tubers for 7-10 days before transplanting.

Monitor tubers closely and provide ideal conditions for strong transplants.

When to Transplant Dahlias from Pots into the Garden

Determining transplant timing takes a little practice and observation. Move tubers outdoors based on these factors:

  • After the average last spring frost date in your area.
  • When soil is warm, at least 60°F.
  • When sprouts are 4-6 inches tall with multiple sets of leaves.
  • After hardening off pots for 7-10 days.
  • When beds are prepped and ready for planting!

Wait until all frost risk has passed before exposing tender tubers to the elements.

How to Transplant Potted Dahlia Tubers

Transplanting pre-sprouted tubers from pots is fast and easy:

  • Water pots well a day before to keep soil intact around roots.
  • Carefully remove tubers from pots, disturbing roots as little as possible.
  • Plant at same level as in pots, keeping sprouts above ground.
  • Space plants 18-24 inches apart in beds.
  • Water transplants well and provide shade for a few days if hot.
  • Stake taller varieties for support as they become established.

With a gentle hand, pot-started tubers will transplant seamlessly into garden beds.

The Advantage of an Early Start

Getting a head start on the season by planting dahlia tubers in pots takes a bit of forethought and effort. But the advantages of bigger plants, longer bloom periods, and flexibility in small gardens make it well worth it! With the right timing and care, your potted tubers will flourish into gorgeous, floriferous dahlia plants.

By starting dahlia tubers indoors ahead of planting time, gardeners can gain up to a month of extra growth compared to tubers direct sown into garden beds. Follow this complete guide on the ideal timing, materials, care and transplanting techniques for success with potted tubers. With a bit of practice, you’ll be rewarded with thriving, early-blooming dahlias that keep your garden vibrant for months on end.

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 to grow everything and is always unsure of how much space to give to flowers vs. vegetables, starting my dahlia tubers in pots lets me grow a lot in one area while always having plants ready to be moved. 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. It has ranunculus and anemone flowers that are almost ready to bloom right now, but they 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.

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It’s now safe to plant dahlia tubers in the ground here in Southern California, but I can’t because my garden is full of ranunculus! Also, if I wait until the ranunculus are gone to plant my dahlia tubers, they will be very behind in the growing season and flowers will be a long way off. That’s why I like putting dahlia tubers in pots—maybe you do too?

If that doesn’t work for you, another reason to start dahlias early in pots is to get a head start on the growing season in colder places. Dahlia tubers can be started indoors in early spring, but they need more care and work. They can be started in pots. This way, your dahlia tubers can sprout, grow strong roots, and grow before they are moved into the garden. Keep in mind, though, that dahlias don’t do well in frost, so once they have sprouted, the goal is to keep them warm and give them enough light.

Because of the weather where I live, I can keep my dahlia tubers in pots in a warm corner of my garden, close to a fence and rock wall. If it’s going to be cold at night (in the 30s), I even cover my dahlia pots for the night with row covers or other pots that have been turned upside down.

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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.

Watering After Planting Tubers

A common question is whether or not to water dahlia tubers after planting them. I think this may depend on the climate or zone. Southern California is so warm in the winter—some days are almost too hot to handle—that I don’t think my tubers will rot, but I also don’t want them to dry out completely. Therefore, I do water my dahlia tubers slightly after planting and continue to monitor throughout the season.

Once the dahlia tubers have sprouted, make sure the soil stays moist and the plants stay out of the frost in a warm place. And that’s how you can start dahlias early in pots!.

How to Plant Dahlia Tubers in Pots for Earlier Blooms


Should you soak dahlia tubers before planting?

If you want to grow dahlias early, you can start by planting their tubers in big pots filled with peat-free multi-purpose compost in March or early April. But before you do that, soak the tubers in a bucket of warm water for an hour.

What size pots to start dahlia tubers?

The bigger the pot, the better. Each dahlia tuber needs 12”x12”x12” of space to grow well. Don’t plant too many dahlia tubers in one pot! Plant once all danger of freezing has left the forecast.

How long does it take for potted dahlias to sprout?

When you are planting dahlia tubers, you may or may not see a sprout. Often, the tubers don’t sprout until they have been in the ground (or in a pot) for 4 to 6 weeks. It takes tubers longer to come out of dormancy when they are planted early in the season and the weather is cool.

How do you start dahlia tubers indoors?

Place your dahlia tuber vertically in the potting mix so that you can see the neck, and cover the rest of the pot with potting soil. Be careful not to water the soil immediately, wait until you see eye development (see below) before watering.

Can you put a dahlia tuber in a potting mix?

PHOTO NO. 1: The potting mix just covered the dahlia tuber when it was placed on the bottom 1/3 mixture of soil and copolymer slurry. The eye of the root was left exposed. The plant has grown beyond the top of the pot and has been staked, so it is ready to be completely filled in with potting soil.

How do you plant a dahlia tuber?

Planting the Tubers: Gently place the dahlia tuber in the pot with the “neck” (the area where the sprout will emerge) facing upwards and slightly exposed. Watering Wisely: Lightly mist the soil surface to moisten it. Avoid soaking the tuber, as this can lead to rot. Warmth and Sunshine: Locate your pots in a sunny window.

Do dahlias bloom in pots?

Lora Ashley dahlia bloom. One of my secrets to growing stunning dahlias in pots is to first “wake up” the tubers. By “waking them up”, I mean get the eyes to start sprouting and some roots growing. The eyes are where the dahlia stalks (and future blooms!) come from and if your tuber does not have any your dahlia will not grow.

When should I plant dahlia tubers?

The ideal time for potting up dahlia tubers for an early start is in late March to early April. This ensures they’re ready for transplanting outdoors by mid-May when soil temperatures have warmed in most locations. Pots: Choose pots with drainage holes sized appropriately for your dahlia tubers (6-inch to 1-gallon).

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