The Pros and Cons of Early Dahlias

Last week I was sitting around with some farmer friends and we started talking about dahlias— cause it’s almost that time ya know? A few growers mentioned how they had left their tubers in the ground to overwinter and thus began a discussion on the pros and cons of early dahlia blooms. It was some good stuff so I thought I’d share what we talked about!

First off— who doesn’t want to see their dahlias earlier rather than later? So point #1 in the pro category. In order to get earlier blooming dahlias, you need to either overwinter (if that works for your zone), plant very early, or pre-sprout and pot up indoors. Any of these methods would bring dahlias on early. In my zone 7b climate, early dahlias are usually blooming mid- June. If you plant after our last frost date, then usually mid July for first bloom. If you are warmer or colder, adjust accordingly. A lot of this info is a bit more specific to warm hot climates but from what I know- if you are colder, then early blooms wouldn’t be much of a thing without a temp controlled greenhouse.

I really think it’s a matter of expectations if you are going for early blooms. I know some people do it intentionally but I suspect most folks just don’t want to have to dig them up in the fall (and I don’t blame you!).

So in the con category- early blooms are way more susceptible to pest problems. June brings thrips and Japanese beetles in my area. Might as well go ahead and add in the grasshoppers that will be in by late June and well you can forget about getting a perfect bloom without an organza bag!

Also in the con category- vase life! Dahlias that bloom in hot weather have an average vase life of 3-5 days and big dinnerplate types- You might as well enjoy them on the plant. Years ago I had a beautiful flush of cafes in mid- July. I thought it was going to be awesome until I started testing vase life and I was getting 3 days! That’s really not even usable for an event. So now I program my cafes to come on much later when the weather is cooler.

So where does that put us if you left your tubers in the ground overwinter? You have a few options.

1. You can accept the pest pressure and realize the first blooms are not going to be perfect unless you bag them or spray them but honestly a lot of sprays won’t get the thrips.
2. If you sell your blooms, advise your customers of the shortened vase life. I think this is pretty important because you don’t want to turn people off of using dahlias in arrangements. I make sure to let my customers know the vase life gets better in the fall and that summer dahlias should be used for events only!
3. You can cut your plants back. This is a good option if you want to minimize the work of dahlias and overwinter them. In mid june or when you start seeing buds, cut the plants back by half. You can also use this technique to time out blooms too. On average it will take the plants 6-8 weeks to rebloom if you cut back hard. The exact time depends on the variety.

All in all I don’t think having early blooms is a bad thing but I think it’s worth having the knowledge and correct expectations of how dahlias perform differently in hot weather.

So are you ready for Dahlia Season? If you need a bit of help getting started, join us for our On Farm Workshop- Dahlia Dividing and Planting- April 23. All the info here!

Not local? Check out our virtual Workshop: Dahlia Growing in the South