Dahlia Cuttings: Why I Ditched Root Riot Cubes (And What I Use Instead)

If you want to multiply your dahlias — really multiply them — cuttings are the way to do it. One tuber can become five or more plants in a single season. The earlier you start, the more you'll have. Here's how I've been building my dahlia inventory this year, and the change I made to my rooting setup that's made a real difference.

Where My Cuttings Come From:

I've been working with four different sources this season, each with its own rhythm:

• Fall tubers I purchased quite a few last fall specifically to pot up early and take cuttings. To do this well, you need a warm room, grow lights, and enough time to keep an eye on them — they can't dry out once they start sprouting.
  
• Quart-sized plants I bought from Dapper Dahlias in January. These come in already well-established — cut one down and you can have 20 plants quickly. Their customer service was genuinely good; any plants that didn't ship well were replaced without fuss.
  
• Pot tubers: These are dahlias I left in their pots when I planted out into the garden last year. They still produced full-sized plants, but because the tubers were contained, they're densely packed — better for a cutting bed than for dividing. They tend to throw more sprouts than a single field tuber will.
  
• Potted-up tubers For varieties that are poor producers, or ones I want more of, I pull them from storage early. Once the eyes start developing, you're ready to take cuttings.

A Few Things Worth Knowing About Cuttings
Not all cuttings root at the same pace. Stem cuttings — taken from an established plant — and cuttings taken directly from tubers both root in about three weeks for me. Leaf cuttings take longer. Sometimes you'll see roots developing before the foliage above has caught up. That's normal.

One tip I keep coming back to: when taking cuttings from tubers, leave about a dime's width of stem on the tuber. That small bit of stem signals the tuber to produce more sprouts — I've seen as many as four from a single tuber this way.

On rooting hormone: I use Clonex gel. I don't think it hurts, and I've kept it as part of my routine. That said, it's genuinely optional — your call.

Why I Stopped Using Root Riot Cubes
This is the part I wish someone had told me earlier.

Root Riot cubes were a good learning tool when I was first figuring out cuttings. But I've moved on, for two reasons. First, I came to absolutely dread dividing dahlias in the fall and finding that compressed cube material lodged around the neck and worked in between the tubers. Second — and this matters more — I've noticed I get fewer tubers from plants rooted in Root Riot. My best guess is that I wasn't planting the seedlings as deep as I should have been when using them.

What I Use Now
For my scale of growing, I switched to small greenhouses with LED lights and a vent on top. I now fill the cells with seedling mix, press it in firmly, and spray everything down until it's evenly moist.

I remove the bottom leaves, usually with a sanitized Xacto knife.

Then I use a dibbler to make a hole most of the way down, set the cutting in, and press the soil in around the stem to make good contact. That's it.

Oh, and don't forget to label!

One thing I've changed: I've stopped misting the foliage. I think the extra surface moisture was contributing to mold. Now I just keep the soil consistently moist — if it starts to look dry, I spray it.

The rooting ratios have been noticeably better. And come fall, no cube residue to deal with.

Cuttings are one of those skills that feels finicky at first and then clicks. Once it clicks, it's one of the best tools you have for building your dahlia inventory without buying a tuber for every plant you want to grow.

More on what I'm growing this season soon. — From my garden to yours.