How to Plant Hundreds of Dahlia Tubers
1,600 dahlias in our annual field.
April 19, 2024
For every year of farming, the number of Dahlia Tubers we plant on our 1-acre flower farm changes. Most years, the number of Dahlia Tubers we plant has grown because our space has grown; however, this year (2024), we are actually cutting back our Dahlia production to less than half of what we grew last year.
Why would we cut our Dahlia production in half?
Well, it’s simply because we had too many flowers and couldn’t sell them all. Our main sales outlets for our dahlias are: selling bunches directly to florists, mixed retail buckets of bulk flowers to the public (buckets include dahlias but are not solely dahlias), and using a ton of dahlias in our wedding designs.
Still, in 2023 we grew over 1,600 dahlias and most of the plants were so productive that we couldn’t keep up with harvesting, deadheading, and we couldn’t sell all of the blooms. So, to cut down on waste (including materials/time/cost of labor involved — which are all super important waste factors), we are cutting our Dahlia production to less than 800 plants this season in 2024. We’ll see how that number works out and report back.
Related: Will Deer Eat My Field of Dahlias?
How we grew dahlias in sandy soil
I have grown dahlias for the past six years for cut flower production. Success has come in varying degrees. For the first four seasons, I was growing on our first flower farm in a sandy loam soil that drained quickly — great for cycling water, not great for retaining nutrients. The dahlias in that farm were not very floriferous and I never had enough blooms. The maximum amount of Dahlias I was able to plant there was 400, and still, I never had enough blooms to go around between selling to florists and needing dahlias for my own wedding work.
Dahlia bed on the left in sandy loam soil, mulched with straw, 12 inch plant spacing.
At that first farm with sandy soil, I was growing dahlias in 36 inch wide beds, two rows of dahlias per bed with each dahlia tuber spaced 12 inches apart. It was a tight planting because I was working with a small amount of space and I aimed to fit as many plants in that space as I reasonably could. I never used landscape fabric on those dahlias — I simply dug holes with a shovel, added a shovelful of composted cow manure per hole, placed the Dahlia tuber in the hole about 4 inches deep, and covered it up. The first year, I added alfalfa pellets to the beds which was a mistake because there was too much nitrogenous action which caused a lot of healthy green growth but hardly any flowers.
Related: I do use Alfalfa Pellets on most other plantings - Read about our soil prep here
In those first four years, I mulched the dahlias with a thick layer of straw mulch to help retail soil moisture and organically keep weeds down. I laid one line of drip irrigation (this is the exact drip tape we use) per row of Dahlia Tubers and watered several days per week all summer, which kept the dahlias hydrated and happy in that dry sandy soil.
Still, after growing 400 dahlias like that every year, I yearned to have enough cuttable blooms with a reasonable amount of extra to spare, say 10%. So naturally, I went on to plant way too many…
Related: Are Dahlias Hard to Grow?
growing dahlias in wet clay soil actually works, with observation
In 2022, we purchased our own farm property in Burt, NY and planted dahlias there for the first time. The soil profile is completely different than the other farm and it has been a bit of a learning curve. Despite this new soil having a heavy clay composition and tons of rocks (which is completely different from the other soil we were used to growing in), a soil test revealed that it is completely balanced in nutrients with a pH of 7.0. Our dahlias grow and bloom unbelievably well here — so much better than the other farm, and for that I am beyond grateful!
I’ll go into more detail later on in this post about what we’ve learned about growing dahlias in clay soil.
planting dahlia tubers with a tractor
That first year on our new farm in 2022, I planted 900 Dahlia tubers at 12 inch spacing. We had so much going on that spring, with multiple flower farms (I was still maintaining the original farm for another two seasons while we got the new farm up and running), so we decided to plant the dahlias in the quickest way we knew how… using our new Kubota tractor.
Related: Choosing a Tractor for the Flower Farm
In order to efficiently and quickly plant all 900 tubers in one day with just two people, I acquired a Middlebuster attachment for our tractor. We pulled the middlebuster down a freshly tilled, open area to create long trenches. We did this instead of digging individual holes for the dahlia tubers, so all I had to do was walk along the trench with a bin of Dahlia Tubers and drop the tubers into the trenches. I did this very quickly without worrying whether the eyes were pointed up or down, knowing the dahlias would figure it out on their own.
The 2022 Dahlia field planted using the middlebuster.
The middlebuster dug the trenches about 6 inches deep, which is the depth I was aiming for to plant the tubers (trenching depth is adjustable based on how you install the attachment to your tractor). After the Dahlia tubers were laid in the trenches, I simply went down the rows with a hard rake, raking the soil back down into the trench and over the tubers. This would have been even quicker and more efficient with a Garden Bedder/Hiller Attachment for the tractor, but we didn’t have that at the time (the hiller attachment has become an invaluable tool on our farm — we’ve used it to hill up every single planting bed on our farm).
The dahlias grew great that year in the trench planting — they were planted so deeply that they didn’t even require any staking in our totally exposed, super windy field. The only problem with this setup was the weeds — they grew out of control because I did not have the time to address them, and when using a middlebuster, you can’t use landscape fabric in the planting beds to keep the weeds down. Just something to consider.
So, if you have 1,000+ dahlia tubers to plant and some space to spare (because you need to be able to drive a tractor between the single rows), then a middlebuster is an awesome way to plant a ton of Dahlia Tubers at once.
We now have a 96’x30’ high tunnel erected in this spot, which will be another fun(?) learning experience in the years to come!
Related: How to Plant Clover Pathways
planting dahlia tubers with an auger
Another quick way to dig holes for Dahlia tubers is to use an Auger Drill Bit on an electric drill. While one person walks down the bed drilling holes with the Auger, another person can come behind and drop the Dahlia tubers into the holes and quickly cover them up. Even better, the holes could be covered up using the Bed Hiller Attachment on your tractor, if you have one. This quick planting process would allow for double rows of dahlias per bed, as opposed to the single rows of dahlias planted with the Middlebuster. I have not planted dahlia tubers this way, but I know people who have with success.
drainage pattern is important when planting dahlias
The main issue we’ve faced in our new clay field is the high water table and the way the rainwater drains, and sits, in our field.
In 2023, we planted over 1,600 Dahlia tubers just to the west of the 2022 planting. Before planting, I was unaware of the way the water sits in that part of the field. When you stand back and look at the field, you can literally see it dip in the center, which is an indicator that water sits in that spot and the soil is compacted. It was amazing (and horrifying) to watch all of the dahlias in the center of that field grow stunted or rot in the standing water. A learning experience, for sure!
Our 2023 Dahlia field.
planting dahlias in landscape fabric
This 2023 planting, we did not use the middlebuster again because I wanted to plant the dahlias in landscape fabric to keep the weeds under control. It took me so, so, so long (an entire week) to lay the landscape fabric, blow the holes with a Mag Torch, and plant the dahlia tubers — but in hindsight, it saved me a TON of time and stress not having to worry about weeding this area. There is always an upside and a downside to everything we do at the farm.
I believe the landscape fabric helped heat the soil up which caused the dahlias to come up quicker (we had cuttable blooms in mid-July, which is pretty amazing for field planted dahlias in Zone 6b). Also, because I planted each individual tuber by hand, I wasn’t planting as deeply as the trenched dahlias in 2022 so they came up quicker because of that, too. These dahlias were more prone to falling over because they were not planted deeply, so they needed to be staked — we used wooden posts, u-posts and tomato twine. Plant spacing for this Dahlia planting was 16” apart in two rows. We will continue this spacing going forward, using the pre-blown holes in the landscape fabric.
Our 2023 dahlias in landscape fabric — you can see how the field dips down in the middle.
fertilizers for dahlias in clay soil
Since our soil is completely balanced in nutrients (for now), in 2023, we only used a handful of Bone Meal per tuber hole, and covered the holes with a shovelful of composted animal manure. I sprayed the field with one application of homemade compost tea in July, which I would have done more often, but I did not prioritize this task and it got lost in the flurry of the season.
We did not use drip irrigation at all on the dahlias — remember we have a wet field — and we spot-watered only a few times during the season when it was super dry. 2023 was a rainy season in Western New York, so we were spared having to worry about consistently watering the dahlias. The landscape fabric also helped to hold moisture in the soil. The whole thing worked out really well, except for the middle of patch being stunted and/or dead due to standing water in our heavy clay soil.
Moving forward, in 2024, we are going to avoid planting in the compacted wet spots. We’ll plant between 700-800 dahlias in the best part of the field where the dahlias were planted last year, and also in our new high tunnel, which is right next to that “good” part of the field.
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I look forward to reporting on growing dahlias in the high tunnel! I hope this article has been helpful for anyone feeling overwhelmed with planting hundreds of Dahlia tubers. There are so many different ways to do this — I’ve done it several different ways — and I hope my experiences are useful to you.
peace, love, plant magic.
Fran Parrish