How to Dig, Divide & Store Dahlias

When to dig

Dahlias aren't hardy in Zone 5b, so the tubers come out of the ground every fall. Wait for the first hard frost to blacken the foliage. That frost tells the plant to stop growing and helps the tuber skins toughen up for storage. Many growers then wait another week or two before digging. In the Lakes Region that usually means late October, and always before the ground freezes.

What you'll need

• A garden fork (it's gentler than a shovel)
• Sharp, clean snips or pruners, plus rubbing alcohol to wipe them
• Labels and a pencil or permanent marker
• Bins or crates, and a storage medium such as vermiculite, peat moss or wood shavings

Digging, step by step

1. Cut the stalks down to about 4–6 inches. Leave a stub you can hold and label.
2. Loosen the soil in a wide circle about a foot from the stalk, then lift the clump gently from underneath. The necks that connect each tuber to the crown snap easily.
3. Rinse off the soil with a hose so you can see the eyes.
4. Label the clump right away. You'll be glad you did in spring.

Dividing

A tuber will only grow if it has three things: a plump tuber, an unbroken neck, and at least one eye on the piece of crown attached to it. Eyes are small bumps, often pink or white, where last year's stem meets the tubers.

• Start by cutting the clump in half through the crown, then keep cutting until each piece has an eye.
• Discard tubers with broken necks, soft spots, or no crown attached. They can't sprout.
• Can't see any eyes? They're easier to spot after a week or two, or in spring. You can store the clump whole and divide it before planting.

Curing and storing

Let the divisions dry for a few hours to a day, just until the cut surfaces callus over. Then pack them in a bin with a slightly damp medium, with the tubers not touching if you can. Keep them somewhere dark and cool, ideally 40–50°F: a basement corner, an insulated garage or a crawl space that never freezes.

Check them once a month

• Soft, mushy or moldy? Cut out small spots and dust the cut, or throw out anything badly rotted before it spreads.
• Shriveling? Storage is too dry. Mist the medium lightly or add a little damp vermiculite.
• Sprouting early? Storage is too warm. Move the bin somewhere cooler.

This is exactly how we prepare every tuber we sell.