Why Are My Dahlias Not Blooming?!

It feels like you did everything right, yet your dahlia buds are still not opening. Day after day, you walk down your rows of cut flowers and stand in front of your dahlia plants, asking Why aren’t my dahlias thriving? Why did my dahlias not flower? How do I get my dahlias to bloom?!

Have no fear! You’ve come to the right place.

In this blog post, I’ll give you five reasons your dahlias might not be blooming this season and ways to remedy them so you don’t have to go another growing season without seeing the queens of the cut flower garden in their glory!

A woman with long brown hair stands in a lush garden, smiling and holding a bucket of colorful dahlia flowers. She is wearing a light-colored dress and a white knit cardigan. The vibrant flowers in the bucket contrast with the green foliage in the background.

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Growing Dahlias Is Hard

Once you’ve hit the end of August and you’re still not seeing blooms, it can feel devastating, but if you’re dahlia buds are rotting, or your dahlias aren’t growing tall, you’re not a failure! Especially in a cold climate and short growing season like Zone 3, it can be a real struggle to get dahlias to bloom earlier, or at all, especially when dahlias bloom so close to the end of the growing season.

I grow some dahlia tubers in my mother’s garden and some on my own flower farm. The dahlia tubers in my mom’s garden are flourishing and have had consistent blooms since the beginning of August, while my dahlias have really been struggling. I’ve only harvested maybe five blooms so far the entire month of August, and I have at least ten times the amount of tubers she does!

Why aren’t my dahlias growing?

I’m convinced that good soil health is crucial for the health of your dahlias. While I’m still going to be working on my soil for the next couple of years, I think the quick fix to remedy this next year is to make sure that I put a handful of manure, worm casings, or something similar into the soil for every single tuber. This will be time-consuming, but I think it will pay off.

P.S. I’ve done something similar for the pumpkins I planted in my poor soil, and that scoop or two of manure in the hole really makes a difference!

A vibrant bouquet of dahlias in various colors including shades of red, pink, orange, yellow, and purple. The flowers are displayed against a blurred background of greenery, highlighting their rich and diverse hues.

5 Reasons Your Dahlias Aren’t Blooming

1. Too Much Nitrogen

Nitrogen is one of the foundational ingredients in many fertizliers, because it promotes healthy production of new leaves. If your dahlias are all leaves and no flowers, this could be why. Too much nitrogen in the soil can be deteimntal for dahlias, as it makes dahlias prioritize leaf growth over the production of flowers. This is a common reason why cut flower gardeners won’t see blooms if their dahlia plants are otherwise healthy.

To promote dahlia blooms, I fertilize them with Gaia Power Bloom 2-8-4 from West Coast Seeds (it even has beautiful blooming dahlias on the container, so you know it must be good!). You can also use bonemeal or a homemade concoction of eggshells and vinegar to encourage dahlias to bloom and prevent too much nitrogen from being in the soil.

Close-up of two unopened dahlia buds on a tall, leafy stem with a blurred background of a green garden. The buds are perched atop dark red stems, with foliage and various plants softly out of focus, suggesting a serene, natural setting.

Related: How to Get More Dahlias for Free with Cuttings

2. Too Much Water

If your dahlias haven’t flowered, another possible reason could be overwatering. The question of how often to water dahlias is a little bit tricky to answer. If you water too much, your dahlia tubers will start to rot and you’ll kill your plant. If you water too little, your dahlia will start to look really droopy. So, while there’s no perfect rule of thumb, I would just water when the soil is getting close to dry. What exactly is “close to dry?” If you touch your fingertips to the soil and comes up when you remove your fingers, it’s probably close to dry.

A single deep red dahlia flower in full bloom with an unopened bud beside it, situated among green foliage. The background is a bit blurred, highlighting the rich colors and intricate petals of the blooming dahlia.

Related: How to Overwinter Dahlias in Cold Climates

3. Thrips

Thrips are a common pest found on dahlia plants. The best method is prevention, and I find the easiest method of preventing thrips is to use the little mesh party bags pictured below. However, if your flowers are already infested, some tried-and-true methods do exist to remedy this. Check out this blog post for four ways to get rid of thrips so you can enjoy your beautiful blooms in peace!

Close-up of green plants with dark leaves. Some dahlia flowers are covered with white mesh bags, probably for protection or to collect seeds. The scene suggests a garden or farm setting with a focus on plant preservation or breeding.

4. Not Started Soon Enough

I find that waiting to start your tubers until May without waking them up is a huge no-no, especially in a slow-growing season. If you’re a cold-climate flower grower like me and still struggling with your soil, heed this advice. Any of my tubers that I didn’t pre-start before putting in the ground still don’t have a single promising bud on them as of the end of August. If you really want to ensure that you’re going to get blooms, you really must start waking up your tubers in April at the very latest.

If you want to learn more about starting your dahlias early, check out this video:

Related: How to Grow Dahlias in a Short Growing Season and Cold Climate

5. Variety

Sometimes, a lack of blooms is just an issue with the variety. Did you know that some dahlias take up to two months to wake up and start producing anything? This is why when I invest in a new dahlia variety, I always look to see in the seller’s notes if it’s “early to bloom” or if it’s “prolific.” Because, if I know ahead of time that a variety is going to take its sweet time, I’ll avoid buying it! I don’t have time for that, as my season is way too short, and the frost comes way too soon. Whether the dahlia variety you’re growing is slow to eye up or wake up, or you’ve just grown a later-blooming variety, there isn’t much you can do if it’s natural for that variety!

A close-up of a budding dahlia plant with green leaves and elongated stems. The tallest bud at the top has a round shape with dark streaks, ready to bloom. The background features blurred, grassy vegetation in varying shades of green and brown.

Related: Swoon-Worthy Dahlia Varieties for your Cut Flower Garden

If you want more specific advice for growing dahlias, I always suggest Connie Thompson’s book Connie’s Dahlias: A Beginner’s Guide. She has decades of dahlia-growing experience and writes for cut flower gardeners in all growing zones!

If you liked this blog post, find me on Facebook, TikTok, and Instagram for more cold-climate vegetable gardening tips, delicious recipes, and cut flower goodness! I also make weekly videos over on my YouTube channel. I hope to see you there!

READY TO GROW YOUR OWN BEAUTIFUL CUT FLOWER GARDEN WITHOUT THE HASSLE?

I’ve taken all the guesswork out of creating a cut flower garden with my e-book, Cut Flowers Made Simple. It’s the perfect way for beginner and intermediate gardeners to start their own cut flower garden with or without seed starting.

Finally, you can create a stunning cut flower garden with everything you need to make beautiful bouquets all summer long.