DAHLIAS: Digging and storing

Digging up and dividing Dahlias is an essential part of their care, ensuring healthy growth and abundant blooms for the next season. Home gardeners don’t need to lift and divide their plants each year although it is advisable to do so. If the drainage is good the rootstock will survive winter and regrow in spring. Each plant will produce a clump of new tubers which, undivided, will produce smaller plants with poorer quality blooms. Eventually the plant will become so congested and the results so poor that it should be lifted and divided. Here’s a step-by-step guide on how to do it effectively.

Tubers

A tuber is a swollen root containing the food that supports the growth in spring until feeder roots develop. Each tuber is attached to the base of the plant stalk (the crown) by a connector (the neck) and has a tail from which the feeder roots spread.

The number and size of the tubers in a clump, the size of the crown and the thickness of the necks depends partly on the growing conditions but can vary significantly from one variety to another.

By dividing the clump to separate the tubers, each with a section of the crown from which the dahlia will reshoot in Spring, you can increase the stock of your favourite plants.

Timing

• Best Time: The ideal time to dig and divide dahlias in Australia is during late autumn to early winter, after the first frost but before the ground becomes too cold and wet. In many regions, this is typically around May to June.

Tools and Materials Needed

• Garden fork or spade

• Sharp knife or secateurs

• Garden gloves

• Bucket of water

• Sulfur or fungicide (optional)

• Labels and marker

Steps to Dig and Divide Dahlias

1. Preparation

• Cut Back the Foliage: Once the foliage has been blackened by frost, cut the stems back to about 10-15 cm (4-6 inches) above the ground.

2. Digging Up the Tubers

• Loosen the Soil: Using a garden fork or spade, start loosening the soil around the dahlia clump, about 30-40cm away from the stems to avoid damaging the tubers.

• Lift the Clump: Carefully lift the entire clump out of the ground, gently shaking off excess soil.

3. Cleaning the Tubers

• Wash the Tubers: Rinse the tubers in a bucket of water to remove remaining soil, making it easier to see where to divide them.

OR

• If you happen to have a suitable brush, or air hose you may wish to blast the dirt off without the use of water which may help reduce the risk of rot while storing

4. Dividing the Tubers

• Identify Eyes: Each tuber needs at least one eye (growth bud) to sprout. These are usually found near the base of the stem.

• Divide: Using a sharp knife or secateurs, cut the tubers into sections, ensuring each piece has at least one eye. Avoid making the divisions too small; a good size is about the size of a fist.

5. Treating and Drying

• Optional Fungicide: Dust the cut ends with sulfur or a fungicide to prevent rot.

• Drying: Let the divided tubers dry for a day or two in a cool, dry place. This helps to heal the cut surfaces.

6. Storing Tubers

• Storage Environment: Store the tubers in a cool, dry, and dark place. Ideal conditions are around 4-10°C (40-50°F) with good air circulation.

• Storage Medium: Place the tubers in a container with peat moss, sand, or sawdust to prevent them from drying out completely.

7. Labeling

• Label Varieties: If you have different varieties of dahlias, label them before storing to keep track of which is which.

Replanting

• Timing: Replant the divided tubers in early spring, after the danger of frost has passed and the soil has warmed up.

• Planting Depth: Plant them about 10-15 cm (4-6 inches) deep, with the eye facing up.

• Spacing: Space the tubers about 60-90 cm (24-36 inches) apart, depending on the variety's growth habit.

By following these steps, you can successfully dig, divide, and store your dahlia tubers, ensuring healthy and vibrant plants for the next growing season.