My First Year Growing Dahlias: Grow Dahlias with Me!

This year I decided to start our cut flower garden - something I’ve been wanting to have in our home almost as much as growing veggies. A little dream of mine is to grow all my favourite flowers so that I can simply head into the garden anytime I feel like arranging some flowers for the home. Last spring when it came to planting time, I decided to start off with one of my favourites: dahlias!

Of the past couple of weeks, my first dahlias have finally started to flower and so I thought I’d take some snaps and put together this post! This post is a bit about all the research I’ve been doing about growing dahlias, as well as my own experiences in my first year growing this absolutely stunner of a flower. There’s still so much more to learn and I can’t wait to see where my dahlia growing journey takes me over the coming years.

I wanted to share this post asap so took pictures as soon as they started blooming but since writing this post, more of my varieties have coming along which has made me even more excited and in love with this beautiful flower!

WHERE TO GET TUBERS

You can find dahlia tubers online from dahlia farms or nurseries. I got most of my tubers this year from Tesselaar Plants & Flowers which is the dedicated plant part of the business run by the same people who run Tesselaar Tulip Festival & KaBloom! Dahlia tubers also divide themselves when planted so you may also be able to find and share dahlia tubers with fellow dahlia growing friends.

WHEN TO PLANT

Dahlias are planted in spring after the last frost has occurred. Usually in Melbourne, dahlia growers advise planting two weeks either side of Melbourne Cup Day, which is the first week of November. This year I planted my dahlia tubers about one week after Melbourne Cup with the last of them planted 2-3 weeks after Melbourne Cup Day. If I was more organised then I would have tried to plant them earlier, but all good!

WHERE TO PLANT

Dahlias love sun but Aussie sun is pretty harsh. So if you’re choosing between a number of possible locations, somewhere that has morning sun and afternoon shade (e.g. an east facing spot) is better than somewhere with strong afternoon sun (e.g. a west facing spot).

PREPARING TO PLANT DAHLIA TUBERS

Before planting your dahlia tubers, prepare the soil by adding some cow manure or by planting a green manure crop in winter in order to increase organic matter in the soils.

I planted my dahlias into Birdies Heritage Range wooden raised garden beds. Each bed is 2 packs of 80cm x 80cm sized beds which when joined together, gets you three squares worth of planting space. The garden beds are easily customised and you can add more garden beds by simply joining them together. They’re also easy to move around as well. I love this range and have these raised beds all over our garden.

HOW TO PLANT DAHLIA TUBERS

To plant your dahlia tubers, first dig a hole that’s around 10cm deep. Then, lie your tuber flat along the soil. If you can tell which side is the part is the eye - the part that the stalk shoots from (it’ll look like an old stalk used to be there) and which part is the tail - the part where the roots shoot from, then you can rest the tuber so that the eye sits higher and the tail sits slightly lower. But I don’t think this is completely necessary - lying flat is probably just as good.

Then, fill up the hole with soil. Don’t water the tubers once they are in the ground, as this may cause them to rot. Instead, wait for the green growth to come up before you start watering them.

Dahlias can grow up to 150cm tall and also need lots of space. Usually it’s advised to give them around 75cm-100cm space between plants however I saw online a dahlia grower suggest they were fine to plant closer together which is what I did this year to see how they’d fare. I planted 12 tubers spaced equally in each 80cm x 240cm box. Meaning they had approximately 40cm breathing space around each plant.

My verdict: I think my dahlias did fine planted close together. If anything they probably grew a bit slower than expected due to competition of nutrients (and probably slight lack of sunshine as it’s not the best location that I put them in!) Though I think I’d probably try plant them further apart in the future. My main reason for wanting to do this next time was that as the plants grew, they started to mesh into each other and I could no longer tell which stem was from which plant which made it more difficult when it came to pruning and other maintenance.

NOTE: ALSO PLANT STAKES!

Dahlias grow tall and absolutely must be staked for the best chance of success else the flower stems won’t be able to support themselves and snap. Hence, it’s easier to plant your dahlias altogether if possible, so that you can stake them together.

As to what stakes to use:

You can go with wooden stakes and then use twine to secure dahlias to the stakes, or use twine to create a vertical support that dahlias can lean onto.

Alternatively, you can commercial polypropylene trellis netting which you can then suspend horizontally in multiple layers so that the dahlias grow through the netting and are supported like that. This is what commercial dahlia growers often use and is what I used in our patch, supported by Whites ultra posts.

PRUNING

One thing that dahlia growers often recommend doing is cutting off the growing tip of the dahlia when you see around four sets of leaves come up. This will encourage the plant to send out side-shoots which means that you’ll end up with more flowers!

I super recommend doing this. I tried to do this with most of my plants but lost track of what I did and didn’t cut in the end so was not able to do a good job at it! Next year, I’ll be taking notes so I can remember which ones I’ve snipped off and which I haven’t.

FERTILISING

Dahlias love being fed cow/sheep manure + a balanced fertiliser with trace elements. If you have tomato fertilisers at home, these will work great for dahlias as they have similar needs.

Aside from preparing a fresh soil of bed with plenty of cow manure, I actually personally did not feed my dahlias this year, mainly because I had too many things to do. They seemed to still do okay, probably because I had a freshly prepared bed. In coming years I will fertilise my plants and am excited to compare the results.

HARVESTING YOUR BLOOMS:

Dahlias are an absolute beauty that you’ll be sure to want to bring some into the house to arrange in vases or gift to friends! When harvesting dahlias, it’s best to pick them in the morning whilst they’re still very fresh. Pop them in the water straight away. Dahlias don’t last the longest when cut, but you’ll still be able to get a good 5ish days out of them.

I personally love to also enjoy the flowers in the garden and leave them as they are!

Do note: If there are flowers that have passed their prime, do cut them off the plant - this is called dead-heading and it encourages the plant in putting their effort into new flowers and can extend the flowering system!