Dahlia Tuber Care in a Dry Climate

While I really want to write about business topics in this issue—because winter is all about refining our business practices while we have the time to learn new skills and make major overhauls—I am saving all of that for “The Business of Flower Farming” meeting in Denver in February. Just two days could fill your head so full and (if implemented) make your business so smooth and profitable, that really you can’t afford to miss it. I hope to see lots of you there!

So, in the meantime, I am going to do a complete 180 and just get super focused and nerdy on dividing and storing dahlias. While I know most of you are already pros at this, and I feel a little sheepish sharing my own process, I have to admit I struggled for a number of years with successfully storing my tubers. I had so many years of lost tubers and lost income and missing out on ordering new ones because I thought the one I had were good and accounted for. I also wanted to share a few tools we use to make the process much quicker.

It’s All About the Weather

One thing I heard at the ASCFG Conference in Raleigh (I can’t remember who said it, but I’m thinking maybe it was Stanton Gill talking about IPM) and it is so true: in farming, it’s all about the weather. While I am so grateful for the internet age and all the available information on farming, our unique and very dry climate makes a lot of things not so transferable from other regions. So when I develop a good practice, especially one for the Southwest climate, I like to share it widely.

Every flower farmer I know does this process of caring for their dahlia tubers a bit differently, so I am just sharing what works for best for us. Some of this I learned through trial and error, and some was sage advice shared by Calvin at Arrowhead Dahlias in Colorado, where they are also in an arid western climate. All the dahlias I have ever purchased from Arrowhead have come in looking amazing, firm with nice visible eyes.

For reference we are in Zone 7; it is the desert, but at high elevation, which means really big temperature swings from day to night, and plenty cold in winter. If you live in a warmer climate you can leave the tubers in the ground. But if you live where the ground freezes you need to dig them up and store them where they won’t freeze. The added benefit to digging them up is that one tuber becomes a clump of tubers, which means you can divide and multiply your stock to get more dahlias each year.

The Process

After a few frosts in the fall, we cut the plants back to about 6” off the ground. We usually do this with loppers or pruners, which is tedious, but this year we tried cutting them back with the flail mower. It didn’t work perfectly, but it was good enough and definitely faster. Then we run the tractor with an undercutter blade on the back down the whole row. Now, this works perfectly. It is way faster and easier on your back than a digging fork, but it depends on your scale and what tools you have at your disposal. Our undercutter is homemade, but I saw some available on www.marketfarm.com.

Next, we pull up the large clumps of tubers and spray them vigorously to get all the dirt off. We then divide those clumps into either individual tubers or clusters of tubers (more or less quartering the clump) depending on the size of the clumps and ease of division. The dividing is actually quite a particular process as each tuber must be attached to an “eye” like the eye on a potato, which is where the sprouts will emerge. But in the case of dahlias, the eyes are close to the stem and getting the most tubers with eyes attached can be quite the puzzle. Many tubers break off without an eye, or are just located on the plant in such a way that they don’t have eyes near them. Also on some varieties the eyes are less obvious than on others. It is mentally challenging and pretty satisfying work, but it is also cold and wet and tedious. And there are so many to divide. There are tons of great tutorials already out there online for how to divide dahlias that I won’t go into the process in depth here.

The Storage

One thing we do differently than a lot of other folks I know is we dig, wash, divide, and pack for storage as much as we can do all in the same day (or dig and wash one day, and divide and pack away the next). Then we just keep repeating the process. Other people often dig all their tubers at once and then store them for a few months in a protected area before they start dividing. In our dry climate, I find that our tubers shrivel out within a few days, especially if left in a warm, sunny place like a greenhouse. We do it in small chunks so the tubers are not left out more than one or two days. Once divided, we pack our tubers into cedar shavings and store them in large plastic bags, in bulb crates, in our root cellar. In wetter climates, plastic bags would probably be a big no-no as things would stay too moist and create mold and rot. Just like in all of farming, it is a big lesson in finding out what works for you, the never-ending trial and error. Don’t reinvent the wheel, but also don’t get too stuck on how other people do it when it doesn’t work for you.

The Lessons Learned

We got all 50 varieties of our dahlia tubers divided by the end of November last year and ended up with about 5,000 clusters for planting this spring. They are stored safely in our root cellar, but I still like to check on them about once a month and make sure no disasters are happening. Now, that number is not counting the 20 or so varieties that we hurriedly got out of the ground when I was worried about some super cold nights in the forecast. After we dug the remainder of the field (way more than the usual amount for one day) we washed them all and set them overnight in our uninsulated barn. When I went out to start dividing in the morning, they were all frozen solid and eventually ended up on the compost heap. Uggghhh, so frustrating.

I could have put them in the walk-in. Or put a space heater in the barn for one night. Or left them in the field for a few more days. So many alternate realities I could play out in my mind. But, instead I will be buying more (and begging some friends) for some replacements for 2019. Nothing is ever safe from the farmer’s mistakes.

Wishing you all the best in the season of acquiring new dahlia tubers – it’s a jungle out there!

Shanti Rade

Whipstone Farm

Shanti Rade Whipstone Farm [email protected]