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It is mid-October and the dahlias in my yard are looking the best they have all summer. Most have been blooming since July, basically nonstop and I’d be hard pressed to find another flower that puts out that kind of performance. Some of their success is part of the nature of dahlias, but the reason they are still blooming, and blooming better than ever, is because I have been good about deadheading them. If you keep on top the deadheading, dahlias will bloom right up until frost.

Sometimes it’s easy to identify spent blooms on deadhead. The petals wilt and start falling off and there’s no doubt that flower needs to go.

But if you miss that stage, which is not uncommon when you have a plant laden with blooms, it can be hard to tell the buds that are about to open from what’s left of the spent flowers.

Turns out, it’s all in the shape. New buds that will still flower are round. Spent flowers have a triangular, pointy shape. In the photo below, the bud yet to open is on the left and the spent flower is on the right.

 You can look a little closer to see the differences as well, but the shape should tell you quickly what’s what. After you’ve identified which bits need to go, trace the flower stem all the way back to its intersection to a leaf and use a pruner to clip it off there. That will promote more blooms and avoid unslightly flowerless stems sticking out here and there.

Even though this spent bud is still slightly open at the top, its elongated shape is a sure sign that it needs to be removed

A closer look at a round bud show petals waiting to unfurl. 

Of course, if you’re just passing by and you see a spent bloom that needs to go, feel free to nip it off with your fingers. That’s far better than doing nothing and you can come back later to take care of the bare stem.

It’s as simple as that. If it’s a triangle, take it off, if it’s round, let it stay attached to the ground. See what I did there? The good news is that it’s so easy, you don’t need my less-than-catchy rhyming device to remember it.

Now get out there and deadhead some dahlias!

15 Responses

  1. I’m wondering how you keep powdery mildew away from your dahlias? We won’t have a freeze for a couple of months (it’s Oct and I’m zone 9B) but the PM is taking over and making the dahlia season much shorter than I thought it could be.

  2. Thanks Erin, you’ve inspired me to grow a few dahlias this year. I even used your early spring potting up method!

  3. Great info!! I just planted my first Dahlias and I’m trying to learn all I can. I planted 2 types … Bohemian Spartacus dinner plate and Pinelands Princess. Can’t wait to see what they do!!

  4. Thanks so much for all your help. I have always wanted to grow Dahlia’s. Finally have some great help from you . thank you again

    1. This is my first year growing dahlias. I wasn’t sure about deadheading..we will see if I can grow them. Liked your article. Very helpful

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