Tubers are the roots of mature plants and look like a cluster of brown, carrot-like roots joined by the previous year’s dried stem. You can buy them from garden centres or by mail order in spring, or use your own tubers that have been overwintered.
When to plant dahlia tubers
Staring dahlias in pots is a great way to get them into growth earlier in the season. Simply plant dahlia tubers in large pots filled with peat-free multi-purpose potting compost in March or early April, and then keep them on a windowsill or in a frost-free greenhouse until late May, when it’s safe to plant them outside.
Starting off dahlia in pots will also encourage them to develop more quickly, so they’re likely to start flowering earlier. Before planting, soak tubers in a bucket of tepid water for an hour so they can fully rehydrate.
Where to buy dahlias online:
- Crocus – Choose from a huge range of colours and shapes, and take advantage of discounted prices if you buy multiple collections of dahlia tubers.
- Thompson & Morgan – Shop the new 2022 range of varieties, including ‘Electro Pink’, which is the world’s first dark leaved cactus dahlia, as well as the dwarf ‘Lubega Power Tropical Punch’ that’s ideal for containers.
- de Jager – Established bulb specialists with an impressive collection of dahlia tubers, in a range of colours and flower shapes.
- Dobies – Great selection on offer, with offers and discounts on specific collections.
You Will Need
- Dahlia tubers
- Large pots
- Peat-free multi-purpose compost
- Plant labels
When planting dahlia tubers, ensure the joint where the roots meet the stem is facing upwards. Label your pots and grow on in a greenhouse or sunny windowsill. Keep the tubers well watered.
Pinch out the tips of the main shoot, down to the top pair of leaves. You also need to remove most of the shoots growing from the tuber, except for five. This encourages bushy plants, strong, vigorous growth and a lot more flowers.
When all risk of frost has passed, harden off your dahlias by placing them outside during the day and bringing them in at night. After a week they will be ready to plant out into their final growing positions.
Basal cuttings from dahlias
Once your dahlias have started sprouting, it’s the perfect time to take basal cuttings. It’s a simple process and will provide you with new plants for free.