Monty Don reveals his dahlia tuber planting tips – for a colorful display

The celebrity gardener shares his top tips on checking the condition of dahlia tubers, and planting them to get the most dazzling displays in the garden this year

dahlia tubers showing the grown flowers in the border
(Image credit: Pippa Blenkinsop)

It's nearly time to awaken your dahlia tubers from their winter hibernation and get ready to kickstart them into action, advises Monty Don.

No garden would be complete without these fabulous flowers, and mid March, says the BBC Gardeners' World presenter, is when you should be checking over dahlia tubers ready for planting.

He shared his advice on how to check and plant dahlia tubers on a Gardeners' World video last March, so now is the perfect time to remind ourselves of his top tips.

dahlia tubers dahlia 'karma choc'

(Image credit: Leigh Clapp)

March is the time to check on the condition of dahlia tubers that you dug up and stored away last winter in a dry, frost-free shed or greenhouse.

To inspect each tuber: 'first get rid of all the loose compost around it and check each dahlia is in good nick,' Monty Don explained. 

dahlia tubers

(Image credit: Pippa Blenkinsop)

The respected gardening broadcaster advised to look for the following to check if the dahlia tuber is good:

  • A nice plump dahlia tuber;
  • Check the tuber is firm;
  • If the dahlia tubers are too shriveled up they are too dry;
  • If they are rotten they are probably too wet;
  • Check for slug damage on the dahlia tuber;
  • A little bit of mould on a tuber is no problem;
  • Cut out bad or damaged tubers

dahlia tubers dahlia bed

(Image credit: Pippa Blenkinsop)

Once you have checked the condition of the dahlia tubers and cut out any bad bits, you can plant them in pots, advised the gardening guru. For growing dahlias successfully, he has these tips.

'Use a plastic pot at this stage that is just big enough for them to grow. We want them to start to develop a root system,' the presenter advised.

Use a good quality, fresh compost as 'dahlias are greedy plants,' he added.

Water the potted dahlias, put them somewhere sheltered and warm to trigger the growth, such as in a cold frame, greenhouse or conservatory, and keep them moist by watering once a week. 

'Do not let them dry out. You'll very quickly see new shoots,' encouraged Monty.

Keep an eye on the mercury levels outside, however, as if another cold snap sweeps in, you may need to cover them with protective fleece.

dahlia tubers dahlias in vases

(Image credit: Janine Joles/ Unsplash)

The dahlias that have been potted under cover will be ready to plant out in the garden in about mid May, when the top growth is about a foot high.

'Dahlias are something that I'm going to be growing here at Longmeadow with a vengeance, because I love them,' added Monty.

Rachel Crow

Rachel is senior content editor, and writes and commissions gardening content for, Homes & Gardens magazine, and its sister titles Period Living Magazine and Country Homes & Interiors. She has written for lifestyle magazines for many years, with a particular focus on gardening, historic houses and arts and crafts, but started out her journalism career in BBC radio, where she enjoyed reporting on and writing programme scripts for all manner of stories. Rachel then moved into regional lifestyle magazines, where the topics she wrote about, and people she interviewed, were as varied and eclectic as they were on radio. Always harboring a passion for homes and gardens, she jumped at the opportunity to work on The English Home and The English Garden magazines for a number of years, before joining the Period Living team, then the wider Homes & Gardens team, specializing in gardens.