Dahlia Growing Guide: My tips for gorgeous dahlias

There’s nothing quite like dahlias in full bloom! Geometric, shaggy, mini and huge, the genetic diversity is just endless. That is why these flowers have captivated the minds of millions making them objectively the most popular flower in the world!

I have been obsessed with Dahlias for nearly a decade now (proof below). And I have learned a thing of two about the process that works for for me.

I have also learned several things NOT to do, starting with DO NOT buy from a big box store. It really isn't worth it. There are over 600 small dahlia farms in the US alone that you can patronize and should have way fewer disease issues.

If you just picked up dahlias from the farm (or have a box sitting on your counter right now), here’s exactly what I recommend.

Start Them Early (It’s Worth It)

If you want earlier blooms and to avoid any rot issues if you have wet ground like me, don’t wait to plant your tubers directly outside.

Instead, pot them up and get them growing indoors first.

• Use fresh potting soil (I buy the organic Coast of Maine potting soil)
• Pot them horizontally or at an angle that fits in the pot with the eye at the highest point. The eye is from where the tuber sprouts (picture below)
• Place them in a warm, bright spot (grow lights are best indoors)
• Water once when you first pot them

Then leave them alone.

The eye is the dark spot (like a pimple) at the top of a tuber. When in doubt, wait until the tuber sprouts and it will be obvious.

NOTE: Do not keep watering until you actually see growth
(unless the soil goes completely bone dry)

This part is important because too much water before they sprout is one of the easiest ways to rot a tuber.

In this picture I am pointing to a dahlia that has sprouted out of the soil:

Once They Sprout, Get Them Outside

As soon as you see green growth, it’s time to start transitioning them outside.

• Move them outdoors to begin hardening off
• Bring them in if temperatures dips below 35F
• If you have grow lights, you can keep them inside longer

This early start gives your dahlias a real head start and you’ll notice it later in the season.

When to Plant Dahlias in the Ground

Dahlias are not frost tolerant, so timing matters.

Plan to plant them outside:
👉 After your last frost
(around May 15th here in New England)

Late is fine, especially if they are potted up and growing. I usually am still getting some dahlias in the first week in June (or this year July!)

How to Plant Dahlia Tubers

Keep it simple:

1. Choose a spot with as much sun as possible
2. Make sure your soil is well-draining
3. Plant tubers 3–4 inches deep
4. Lay them horizontally
5. Space about 12 inches apart

Dahlias don’t like to sit in water but they also don’t want to dry out completely.

👉 Think: consistent moisture, not soggy soil

✂️ Pinching = More Flowers

This is one of the simplest things you can do for better results so don't skip it.

When your plant reaches about 6–12 inches tall:
👉 Pinch out the center growing tip

This encourages:

• A stronger, bushier plant
• More stems
• More flowers throughout the season

It might feel counterintuitive, but it makes a big difference.

💧 Watering & Feeding Dahlias

Once established, dahlias are fairly easy but they do have a few preferences:

• Water consistently (especially in summer heat)
• Avoid letting them dry out completely
• Make sure the soil drains well

And importantly:

👉 Dahlias like to be fed

I use a kelp & seaweed foliar feed to keep plants strong and blooming. It’s an easy addition that helps support growth without overcomplicating things.

This year I am trying out adding Molassas to that same foliar feed, I will update you on how it goes!

Staking

Staking is usually necessary for most dahlias excluding miniature ones and particularly strong ones. For example, Bloomquist York is 6 feet high but incredibly strong.

If you have just a few dahlias, you can stake individual plants using a post and ties or a tomato cage.

This year I staked individual plants, usually 2-3 to 1 stake. You can see some of the twine I used. 
Side note, this deer fence was unnecessary, the deer dont care for dahlias around here.

If you have a whole bed of dahlias I suggest either horatonova netting or coraling the outside.

Here I do both. I do hortonova on some beds and coral others. I prefer coraling because it is generally easier to harvest without messing with netting.

Hortonova:

Coraling

And sometimes you just enjoy a variety that doesnt need it. I plant Cheers all around this garden and never stake it.

Harvest Often = More Blooms 🌸

The more you cut dahlias, the more they produce.

Don’t be shy about harvesting! Plus bonus if you cut longer stems, the plant will continue to give you longer stems. At the very least, deadhead to continue to keep the plant flowering vs. producing seed.

A Note From the Farm

Dahlias reward attention early on.

If you:

• Get them growing before planting out
• Give them sun
• Keep them fed and watered

You’ll be rewarded with a summer full of blooms.

And once you grow them… it’s very hard to stop.

🌼 Want More?

If you’re growing multiple varieties, keeping track of what performs well becomes just as important as growing them.

That’s exactly why my husband and I built Clade! So you can:

Track your varieties

Remember what thrived

Plan better year after year

👉 Learn more about Clade and start tracking your first 20 varieties for free here