I’ve had a fair few requests to write a dahlia guide from those of you that pay any attention to my Instagram stories, where in the summer months at least they are a pretty regular feature.

So, here we are. This is not a definitive, science backed guide, but it’s what I do, and what I have learned over the last 4 years (I think).

Firstly, choose a suitable spot to plant them. You want somewhere in full sun, and while it’s not essential, if your chosen spot is a little sheltered it will go a long way to protecting them from wind and any unsolicited frosts. Soil wise, free draining is best, and slightly acidic is better.

The amount of space you need to allow for each plant will vary by variety, a tiny pompom dahlia plant is unlikely to reach the lofty heights of some of the larger dinner-plate varieties. I’ve had some of these grow to well over 6ft. In general though I allow about a square meter per plant. If anything is too crowded you can always lift the tuber and move it the following year, just like I’m going to have to do. So much of gardening is trial and error, there’s generally more than one route to get the desired outcome.

If you’re starting out growing dahlias for the first time, then you’ll need to buy tubers. So much online choice but which to go for? Think about what you want to do with the flowers themselves. Do you want to cut them and bring them into the house as I do, or do you want to keep them as a decorative feature in your garden as part of a planting scheme. If you enjoy arranging flowers then you’ll prefer varieties that have a long stem and have a good vase life. If you are all about them looking their best outdoors then this is less of a consideration. As spectacular as dinner plate varieties are, they don’t always make the best cut flower. To start with you can’t fit many in a vase, they are top heavy so they don’t sit well, and they don’t always last more than a few days.

All of this said though, choose the varieties that speak to you. The only important consideration really is the height of the plant and whether it will suit the space you’ve planned for it, so it and surrounding plants get the light they need.

I favour using Farmer Gracey for Dahlia tubers, they deliver to me here in France, and on the rare occasion I’ve had tubers that haven’t sprouted they have replaced them FOC. Usually Dahlia tubers can be pre-ordered from December for delivery in the Spring. Popular varieties will sell out though so as with most things in life, book early to avoid dissapointment.

When tubers arrive I plant them in a good sized pot with the stem sticking out above the level of the soil. The biggest threat to my dahlias has always been slugs, so starting them off in pots means you have a better established, bigger plant to go into the ground when they are ready to be planted outside, and ones that might just survive the occasional nibble. I like to put my potted dahlias outside on sunny days and just bring them in overnight to protect them from frost. Only when you’re as certain as you can be that the last frost date has passed should they be planted in the ground. I have planted tubers directly in the ground and found that slugs would nip off any new growth as soon as it appeared so growing on in pots first has always worked better for me.

As your potted dahlias start to grow, keep an eye on the number of shoots. I think the optimum is 3-5 shoots per plant, any more and you can just nip them off at ground level. Of your remaining shoots, when they’ve put out 2 pairs of full leaves, nip off the tops of the shoots. You can use these to make cuttings to get new plants but to be honest I have only limited success with this, and I’ve got too many dahlias anyway sooooo…. I know it seems counter intuitive to chop off your lovely new growth, but each stem will now produce 2 shoots, and you’ll get more flowers and it also helps with longer flower stems too.

When you’re ready to plant outside once all risk of frost has passed, then your major concern is to keep slugs away from them. I do this in several ways religiously for the precious first few weeks and months they are planted outside. Firstly copper rings. You can buy solid copper rings but they are a fortune, so I buy flexible plastic garden edging, (it’s a struggle but you can cut it with good scissors, just don’t use your best ones), and a roll of copper tape. You don’t have to cover the whole ring with tape, just a continuous band that the slugs won’t enjoy sliding over. I think of it as the same sort of effect if we were to lick a battery. Bleugh!. Secondly, beer traps. You can just bury a yoghurt pot up to the level of the soil, it does work but obviously isn’t helped by rain. I’ve found some plastic 3d triangle shaped bags with 2 holes in the front that you use to pour in the beer and these work well. Emptying them (every couple of days) is not for the faint hearted but it does see them off. I have my eye on some ceramic versions which are shaped like snails for Christmas, because that’s how I roll…. Lastly, you’ll need a head torch, a trowel and a bucket, and literally go outside at dusk and pick them off. I’ve filled my small bucket at the start of the growing season in an evening, but you will see numbers diminish rapidly if you persevere. Make sure the edges of your flower beds are strimmed regularly so the slimy little swines have nowhere to hide.

Your dahlias will grow on stems which are quite brittle and will need properly supporting. A dinner plate variety will easily be 6ft tall and the weight of that, especially when it starts to flower, will be too much for the average garden cane. You will need to stake them to avoid the stems snapping off in high winds or with heavy rain. You can choose to tie them in individually with one stake per plant and tie with string as the plant continues to grow. As I grow about 16 in my main bed, I have started to use garden netting strung between multiple stakes which the plants then grow up and through. I find it less work this way and it does the job. The only slight negative is it does make weeding between the plants much more difficult so I apply a reasonable layer of bark chips to help suppress what I can.

Once they’re in and they’re growing nicely, I add some slow release multipurpose plant food granules. Once you start to see flower buds I move to a liquid tomato feed, once every 2-3 weeks, they love it!

Now you’re getting into exciting territory, flower buds! First rule, never cut a dahlia in bud, they are not like roses, that bud will not open. Aim to cut them when they are at least half way open to get the best vase life. If you find they are flowering on very short stems, don’t be afraid to sacrifice a couple of lower buds to get the stem length you want. You’ll get a few less flowers short term, but it will make up for it with an abundance of longer stemmed flowers in the not too distant future. The buds always add a bit of texture and interest to an arrangement anyway I think.

You’ll find a ball of chicken wire is then your best friend, place one in the bottom of your chosen vase or bowl and use it to hold your heavy headed stems in position. You can use something called a flower frog, which is like a round metal cushion covered in inverted copper pins which does the same job. Brocantes here are teeming with beautiful soup tureens for just a few euros which make the most excellent vehicles for dahlias. I also use them for my houseplants, because we all know how expensive houseplant pots are here!

As far as arranging goes, usual rules, no leaves below the water line, cut stems on the diagonal, don’t put them on a radiator or in direct sun if you can help it. You’ll find which of your chosen varieties last the longest through trial and error, but I have a couple of suggestions to help with that.

These are the varieties I grew this year, and this is when they first flowered.

• Totally Tangerine – 21/06
• Lindas Baby – 25/06
• Kogame Fubuki – 25/06
• Myrtyls Folly – 02/07
• Penhill Watermelon – 06/07
• Bohemian Spartacus – 07/07
• Caitlins Joy – 19/07
• Night Butterfly – 20/07
• Penhill Dark monarch – 24/07
• Creme de Cassis – 24/07
• French Can-can – 26/07
• Fancy Pants – 27/07
• Holyhill Spiderwoman – 29/07
• Akita – 29/07
• Peaches & Vanilla – 29/07
• Babylon Bronze – 01/08
• Jowey Linda – 01/08
• Chimacum Davi – 01/08
• Cafe au Lait Twist – 05/08
• Tsuki Yori No Shisha – 13/08
• Fairway Spur – 17/08
• Cafe Au Lait Royale – 28/08
• Islander – 28/08
• Seattle – 17/09
• Kelsie Annie Joy – 17/10

In terms of my favourites, when you’ve gone through spring with very little to put in a vase, the joy of the early flowerers is hard to beat. For this reason I grow the first 2 on this list. Totally tangerine i’ve grown for a few years and It’s reliably first to flower. It’s open centred bent back petals (like an echinacea flower) makes it brilliant for pollinators, but also it’s a great cut flower. It’s followed closely by Lindas baby, which has lovely long stems for cutting, flowers prolifically and has great vase life. It’s often the last man standing when I’m changing out a vase where everything else has gone over. If you grow nothing else, grow these. Later in the season, Caitlin’s Joy and Jowey Linda really come into their own. Long lasting and prolific flowering, their smaller blooms are a great filler for any vase.

For showstoppingly huge blooms, anything proceeded by Penhill, or Cafe au Lait will do you proud.

And for looking epic in your flower border (I found the stems consistently too short to be good cut flower) – Holyhill Spiderwoman.

If I was a dahlia myself, I would totally be Myrtyls Folly. You only have to look at my hair!

Final tip. To get the biggest blooms on your dinner plate varieties, always nip off the little buds that appear either side of your main bigger bud. This allows that bud to reach its full potential, and they don’t call them dinner plates for nothing!

I wish you every success if you choose to grow dahlias next year. They are so addictive, and I am always super excited to see each and every new variety as they appear. There’s nothing like having a house full of cut flowers to brighten your day. I promise it’s easy, otherwise I couldn’t do it! Good luck!

TTFN V x