As your dahlias get older, they tend to get bushier and taller every year. But here’s a pro tip: dividing those dahlia tubers isn’t just a great way to get free plants for your garden—it’s actually really good for the health of the original plant! It’s a win-win for any gardener.
When is the Best Time to Divide?
The best time to divide your dahlia tubers is in the spring, right before you’re ready for planting your dahlias. While you’re checking on them in their winter storage, go ahead and scout out which ones look ready to be split. However, try to resist the urge to cut them while they’re still in winter storage; doing it too early can cause them to sprout prematurely.
Which Tubers Should You Choose?
Look for large, older clumps that have developed several individual tubers. These are your best candidates. When a dahlia clump gets too crowded, the tubers start competing for water and nutrients, which often leads to smaller, less impressive flowers. By thinning them out, you’re actually helping the plant grow stronger and produce those big, beautiful blooms we all love.
Just a heads-up: always stick to healthy tubers. If you see any that are damaged or showing signs of rot, toss those out—they won’t do well and could spread issues to your healthy plants.
How to Divide Your Dahlias: Step-by-Step
Ready to get started? Here is the easiest way to divide your root tubers:
- You can separate the individual tubers pretty easily. A sharp, clean knife works best for a precise cut, but sometimes you can even pull them apart by hand. The most important thing is to make sure every piece you keep has at least one or two “eyes” (those little bumps where the new growth starts). Without an eye, the tuber won’t sprout!
- Try to keep your cuts as clean and small as possible. If you want to be extra careful, you can dust the cut ends with some basic charcoal powder to help disinfect them and prevent rot.
- Once they’re separated, you can treat these new tubers just like any other dahlia. You can put them straight into your garden beds or plant them in pots. Just make sure the “neck” of the tuber is facing up. This way, the new shoots have a direct path to the surface, which helps the plant bloom much earlier in the season.
Generally, you can divide your dahlias every two to three years. You’ll know they’re ready when the clump looks crowded and has plenty of new tubers to spare!
