growing dahlias – my do’s and dont’s and learning as you go

I’ve been growing dahlias here for six or seven years now. It started with a tuber I found in a bargain corner at the garden center, and which turned out to be the most beautiful café au lait! I was immediately hooked, and have been growing them ever since, in increasing quantities each year.

Like everything else in the garden, there is an element of trial and error in growing dahlias. It took me a while for example to understand that I can leave some dahlias in the ground in certain parts of the garden, whereas elsewhere I have to lift them because the earth is too damp during the winter.

Like so many others, I have admired the long beds of dahlias that populate Instagram like the one at Charlie McCormicks house in England. I attempted the same thing this year, planting 45 tubers along a 25 meter wall. On the whole it looks good, but I’m not quite there yet. The key seems to be staking the dahlias individually.

So, although I don’t consider myself a dahlia expert, here is my list of do’s and don’ts – learned the hard way!

Lifting dahlias for the winter.

Yes, I know, that’s what you meant to do. And I have done it for several years, but it is a lot of work. Each tuber needs to be cut back and lifted. Washed clean of any clinging earth, labeled and allowed to dry before storing beyond the reach of frost and light. I’m lucky to have a dark wine cellar with space to store the twenty or so crates that were needed to stock the huge tubers.

You can forget about them all winter, but when the moment comes to replant, it’s easy to feel fainthearted. The realization that the 50 tubers you dug up last autumn need to be divided, and you now find yourself with well over 100 dahlias needing a home … it can come as a shock.

At the end of the day, you have to get to know your garden. If there are beds that are very damp during the winter you will need to lift the dahlias, but those that are well drained could be left. If you’re willing to take the risk of losing some over the winter rather than having the work of lifting and planting – this is your call!

Choosing the right spot

When planting dahlias, it’s important to understand how tall and wide they’ll be when they start growing. This year I accidentally planted some Bel Amour tubers at the front of a bed with a much shorter variety behind. The result is that the shorter dahlia is practically invisible. You also want to have easy access to each dahlia plant for deadheading, so don’t put them at the back of a very deep bed unless you can get in there with a secateur.

Water carefully

Dahlias don’t like to get too hot or too dry. Their leaves look a tad tired, and they have trouble producing as many flowers. The best way to water is a drip pipe – less wasted water and it goes straight to the root. The easiest time to lay down the drip hose is when you plant the tubers.


Deadheading needs to be done regularly in order to continue getting a healthy growth for your dahlias. If you let the plants go to seed, not only are they less pretty, but they also use a lot of their precious energy trying to grow the seeds instead of concentrating on exceptional blooms. And of course, the very best way to deadhead is to pick them before they fade and bring them inside for endless bouquets!

take cuttings

it is very easy to multiply dahlias by dividing the tubers, but did you know you can also propagate by taking cuttings from the plant once the new shoots are about 10 cm high? Cut off small shoots, leave only the top two leaves and the pot immediately around the edge of a large pot filled with good quality earth, already damp.

Stake your dahlias

Possible the most important step! Dahlias can grow 6 feet tall, and their flower heads are heavy, especially in the rain. The ideal is a sturdy stake for each plant. Failing this, a grid system using a sturdy string zig-zagged between stakes. This year I used string and stakes along the bed, but it wasn’t as effective as individually supports for each plant.

Drying your dahlias

You may not know just how beautiful dahlias are when they dry! To do this, cut your flowers for their best blooming moment. Take them inside, away from direct sunlight, but not in the dark. They need plenty of circulating air, and the easiest way to dry them is to stretch a length of chicken wire along a ceiling space, and simply poke the dahlia stems – upside down – through the holes. In 3-4 weeks you’ll be able to create a stunning bouquet of dried dahlias that will last through the winter months.