Learn the Basics of Lifting Your Dahlia Tubers

By Steve K. Lloyd

Copyright © 2024 All Rights Reserved

Some growers are fortunate to live in temperate climate zones and over-winter their dahlia tubers in the ground. You qualify if your soil is cold enough to preserve the dormant tubers at a cool temperature but mild enough that the winter chill does not freeze the buried tubers. 

In most of the country, however, growers dig their tubers at the end of the growing season and preserve them in a controlled environment until it's time to plant them again in the spring.

Whether digging tubers in the crisp months of autumn or the first sun-dappled days of early spring, a few tips can help make the job easier and help ensure you finish the job with healthy, intact tubers you can plant and enjoy again.

If you only have a few dahlia plants in your garden, you may dig them all up at once and start dividing the clumps. If you have more than a half-dozen, it's best to break the job up and dig a few dahlias every day, dividing as you go. The process takes a fair bit of physical labor, so spreading the task across several days makes it less like work. Also, dealing with just a few different plants at a time makes it easier to keep the varieties straight, so you don't accidentally mix up tags and end up with a pile of Mystery Tubers.

The first step is to gently pull aside the winter mulch if you used it. Ensure a tag or other identification tells you what variety it is.

If you left soaker hose or drip irrigation heads in place over the winter, move them aside so you won't damage them with your digging tools. You can probably still see the dahlia's stem if you cut it just above the ground. This tells you where the central growing point is situated, and the tuber clump radiates fairly equally out from this point.

Once you know where the tuber clump is, use your hand to scribe a circle in the garden soil with a radius of about 12 inches from the stem, or where you think the stem was. When you finish, you'll see a circle 2 feet in diameter, with the stem at the center. Using a shovel or digging fork, gently insert it all around the perimeter of this circle, applying a gentle rocking motion as you go.

After working around the circle, the soil inside should look and feel loose. Work your digging tool around the ring again, angling a little toward the circle's center while applying a little more levering force. You may feel the tool cutting or snapping small roots; that's fine. Just be careful not to stab any tubers if you can help it.

Now, you should be able to lift the entire clump out of the hole. If the clump is heavier than you care to lift, you can use your hands to pull chunks of soil gently from the tuber clump. Do not pull very hard—it's easy to snap tubers. When this happens, the neck of the tuber will often break, destroying the growth potential of that tuber.

As you lift the tuber clump, try cradling it from underneath to prevent the sometimes fragile tubers from sagging under their weight. Lay the cluster on the ground or place it in a tray, basket, or bucket. 

Keep the tag or label with the clump. A great tip is to use plastic tags that tie around the plant's stem and stay with the clump during digging, washing, and dividing. Others report success tying brightly colored surveyor's tape around the clump and writing the name of the dahlia on the tape.

If digging more than one tuber clump, take your tools and containers to the next plant. Follow the same process: locate the central stem, scribe a circle around it, and gently dig and rock until the tubers come free of the surrounding soil.

If you are digging in the fall and plan to over-winter your tubers in clumps (waiting until spring to divide them), you may choose to wash off the dirt that clings to the tubers, allowing the clumps to air dry for 24 hours and then storing the clumps as-is. 

Most growers choose to wash the soil away from the clump with a garden hose, whether they divide the clumps immediately or later. 

Climate, storage capability, and preference may influence when you dig your dahlia tuber clumps, but autumn or spring, the steps are the same. The tubers are tougher and less prone to damage in the fall, but the eyes are usually not readily visible. The eyes typically appear more clearly in the spring, but avoiding damaging a few tubers as you dig and handle the clumps is a little more challenging.

The important thing is to work carefully, remembering to practice good posture when digging and lifting to avoid back and muscle strain. Space out the task so you don't spend an entire day digging and then find you have more tuber clumps than you can readily process. 

Whatever method you use to label your varieties, be sure those tags do not become separated from the tuber clump.

Finally, as you dig, remember to marvel at the incredible resilience and beauty of dahlias, a plant that can reproduce and multiply itself in so many unique ways.

For tips on over-wintering your dahlias, dividing your dahlia tuber clumps, and waking up your tubers for spring planting or cutting beds, check out other great Dahlia Doctor articles on these topics. Happy digging!