Tuberous begonias for dazzling flower power

Begonias are the comeback kid of the horticultural world. Not that they ever truly went out of fashion, but when busy Lizzie downy mildew wiped out supplies of popular Impatiens walleriana a decade ago, gardeners were left searching for bedding alternatives to keep containers and hanging baskets ablaze with summer colour.

The crisis threw the spotlight on tuberous begonias, renowned for their canopies or cascades of vibrant hues that are worthy of an RHS Britain in Bloom medal and non-stop flowering throughout the warmer months. Plus, they’ll thrive in sun or partial shade.

Gardeners often ponder which way up to plant dormant tubers but there’s an easy way to remember. The bowl-shaped underside is where roots will emerge from, so should be pointing downwards, with shoots sprouting from the cupped side, which must face skyward.

Begonias will need to be hardened off, gradually acclimatised to outdoor conditions, before planting out after the danger of frost is over – that’s usually late May in the south or early June in northern regions.

After a month in their final growing positions, boost flowering by liquid-feeding weekly with a high-potassium fertiliser such as tomato food. Plants can be thirsty and flowers may drop prematurely if compost is allowed to bake dry, so water regularly.

Although they’re largely troublefree, taking care to avoid wetting foliage when watering can reduce the risk of leaf spot. Stems can be brittle, so begonias will thank you for planting in a sheltered position.