Race against time for the dahlia buds of May

Things could be worse – 2014 could be the year of late, late spring frosts and then early, early autumn frosts, and dahlias growing in the ground will be turned to mush overnight. So if I grow them in pots, I can find them shelter whenever the temperatures fall.

Dahlias are named after the Swedish botanist, Andreas Dahl, who had an unusual use for the plant – he ate it. He thought the dahlia was better as a vegetable than a flower, and it took quite a time before gardeners got around to cultivating it for its blooms.

Dahlia tubers planted in five-inch pots of decent compost and then kept warm and watered, will soon produce shoots which promise superb late-season colour or offer the chance to propagate even more scintillating flowers.

If you just want your dahlias to bloom, harden off young plants before planting them outside when the threat of frost has finally vanished. Then pop them into a well-dug soil enriched with manure and perked up with a dose of general-purpose fertiliser.

Tall varieties will need staking – a job to do before the plants go into the ground.

Once buried a few inches in their final homes and watered well, just let them grow. As they inch higher, tie them to stakes.

If you want huge flowers, remove all but the central bud; if you want a mass of flowers, pinch out the shoot tips to encourage more side-shoots and blooms.

When the first frost blackens the leaves, cut the stems to 8-10ins and dig up the tubers and the soil surrounding them and pop them away in a shady, frost-free spot for a few days.

Prepare a shallow box with a mixture of garden soil and sand. Clean the tubers and put them in the box, just up to the stem. Then cut back the stems to an inch or two and store the boxes somewhere frost free and out of direct light – between 35 and 50F.

Examine the tubers every few weeks, discarding any that have become soft or mouldy. The healthy survivors can be replanted in spring.