Did you know that dividing your dahlia tubers every year has many benefits? I’ll show you my process for dividing and explain the advantages of splitting these dahlia root clumps annually.
Dahlias are my favorite cut flower in the garden. I know it’s hard to pick just one favorite, and I have many runner-ups, but there is just something magical about them.
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I’m a self-taught hobby gardener, not a Master Gardener. Everything I share with you on my blog is my personal opinion and things that worked for me along the way.
Why It’s Important to Divide Your Dahlia Tubers
This perennial plant grows from tuberous roots and is easily propagated by digging them up and dividing the roots. This will not only encourage the plant to produce more blooms but it will be healthier in the long run by separating the healthy tubers from those that are diseased or rotted.
It’s also a good idea to divide dahlias every year because of how quickly the tubers grow. If they get too large, they will rot or become too heavy to lift and store. Trust me, there has been a season or two when I’ve had trouble picking up a clump of dahlia tubers because it was too big for me to lift!
Materials You Will Need to Divide
When to Divide Your Dahlia Tubers
Dahlias are hardy only in gardening zones 8-11, so if you live in colder climates, you’ll need to dig up your tubers in the fall. If that’s the case, you have a choice of dividing the roots just before you store the tubers for winter, or you can divide them in the spring which is what I do.
I divide my dahlia tubers in the spring, usually in April. I’m in gardening zone 8B with a last frost date of April 18th, so this works best for my climate. When planning when to divide, take into consideration your last frost date. Here are some benefits to splitting your tubers in the spring…
- The eyes on the tuber are more visible in the spring. If you’re really timing it right, you will even see sprouts where the eyes are, making the process that much easier.
- I’m able to discard any rotted or diseased tubers that haven’t made it through the winter.
- My tubers in garden zone 8B stay in the ground, protected by mulch, so I don’t dig them up in the fall.
Digging Up the Tubers
When digging the dahlia tubers out of the ground you will need to be very careful not to damage them. Use a pitchfork or shovel and gently dig around the dahlia clump and pull up with last year’s stock if possible. It works best if you’re able to have two people working together during the process.
If you do end up breaking a tuber apart, there’s no need to worry. There is most likely an eye on one of the tubers that weren’t ruined.
You will need to wash off the tubers before dividing so you can see the eyes. Store them in a potting shed or garage for a few days to allow them to dry.
Dividing the Dahlia Tubers
Each dahlia division needs to have at least one eye and a fat tuber. Every dahlia tuber clump will usually have one large central tuber, the mother tuber, with smaller offshoot tubers that develop throughout the growing season.
Once the clumps have dried, carefully examine each dahlia tuber to see how they made it through the winter. These are the tubers I look to cut from the root clump…
- Any damaged, rotted, or diseased tubers
- Tubers that are small or with skinny necks and no eyes
- The mother tuber because it’s already expended most of its energy. These offshoots usually have white or pink dots around the base of the stem rather than the typical growth eyes.
It is important to use sharp, clean pruners or a knife when cutting your root clumps. Using clean pruners will help to prevent passing any diseases to the tubers. Split the clump in half so the pieces are easier to work with. It’s really up to you whether to divide the sections even smaller, or into individual tubers. Keep in mind that every tuber must have an eye in order to be viable.
I know that trying to find the eye on a dahlia tuber can be challenging, so I have shared a link with you on a great blog post by Gardens By Evelyn that helped me. Dahlia tuber eyes will never develop farther down the neck of the tuber than the collar. Before an eye has sprouted out, it tends to just look like a tiny bump or wart.
The eyes are basically where the stem comes from the following year. So when dividing the tubers, it’s important to separate the clump into sections that include a part of the stem base with an eye and one or more offset tubers.
If you can’t find the eye on the tuber, place it in a moist and warm area for about a week. Once the time has passed, the eyes should begin to sprout which means they are healthy.
Planting the Dahlia Tubers
Dig a hole 4-6 inches deep and lay the tuber on its side, horizontally, with the growing eye facing up. Fill the hole with soil. Space the tubers between 12-18 inches.
Don’t water your newly planted tubers until you see the first green shoots coming up through the ground. Watering before any new growth is visible can cause the tubers to rot. Dahlias love being watered consistently through the growing season. After your dahlias are established, you should water your plants deeply 2-3 times a week for at least 30 minutes. I have a drip system that works really well.
And remember, slugs and snails LOVE dahlias so as soon as you see new growth popping out of the ground, you must use some sort of slug prevention. I use Sluggo which is safe for pets. I can’t tell you how many times I have had slugs eat the plant as it was just starting out.
For more information about growing dahlias including pinching and staking, read my blog post ALL YOU’VE EVER WANTED TO KNOW ABOUT DAHLIAS.
Leave me a comment if you have any questions about this process. Now let’s see more garden tips and tours from my friends.
Until next time,
More Garden Inspiration
Make sure to visit my friends to see what they’re up to in their gardens. It’s always fun to see what’s happening in the other parts of the country.