ERIN MCMULLEN
DAHLIA GROWER

Erin McMullen and her husband, Aaron Gaskey, have been growing dahlias for 17 years. They started Rain Drop Farms in Oregon when she was only 21 years old, initially growing vegetables. Her husband's grandmother gave them 12 dahlia tubers from her own garden to plant. "We rolled our eyes and thought, 'She doesn't understand farming,'" remembers McMullen. But they put the tubers in the ground anyway. "To be quite honest, we totally forgot about them. And then they bloomed and we were like, 'Wow!'"

Now Rain Drop Farms grows one acre of dahlias every year, and farms almost 8 acres of other specialty cut flowers including peonies, sunflowers and roses. They sell to wholesale markets in Portland and Seattle, farmer's markets, direct to designers, have flowers in their CSA boxes, and design for weddings. All this and McMullen is also mom to three beautiful children (including six-month-old Beatrice).

Just in time for Mother's Day, McMullen shares with us what she's learned about growing dahlias over the years, what she'll never do again, and why dahlias are "low maintenance."

YOU GROW ALMOST EVERY TYPE OF FLOWER ON YOUR FARM...ARE DAHLIAS THE MOST DIFFICULT?

Well because we initially planted them and then forgot about them, it was more a of a "survival of the fittest" to begin with, and they seemed fairly low maintenance. Especially compared to other things we had to baby along—things we had to start from seed, pot up, transplant, etc.

I think one of the things that's so daunting about dahlias is that they grow from a tuber, which is out of the norm of what people are used to with gardening. (The only other tuber people are really familiar with is a potato.) That can be intimidating and overwhelming—how to plant the tuber and then what to do with it later. And of course, depending of where you grow them, it can vary dramatically. 

WHAT IS YOUR PROCESS FOR PLANTING DAHLIAS OUT?

Generally we pull the tubers out of storage around the middle of March. We like to have them in the barn, sitting, for a couple of weeks. They're protected in there, they're not going to freeze, but they can start to wake up a little. Their eyes will start to swell, which helps us determine which tubers are alive, and helps to get them going before they go into the soil, which can be wet and cold, even in the spring.

(If there's a dahlia we want to propagate, we will pull some tubers in January or February to wake up and take cuttings, but generally we don't pot up our dahlias—we have too many.)

We try to start planting the first week in April, and the goal is to be done a couple of weeks after that. In terms of amending the soil, we've done it all sorts of different ways. Last year we spent time amending each planting hole, but this year we had a shorter planting window with the weather, so we did an all-purpose fertilizer in the field instead. Whatever you do, you just want to make sure you're not giving them too much nitrogen. If you use an all-purpose 5-5-5 fertilizer (I'd recommend Dr. Earth), that's fine. The nitrogen gives them nice green foliage, but if they have too much, they'll have too much foliage and not enough blooms. The last two numbers are phosphorus and potassium. For dahlias, you want those last two numbers to be higher, which will help with root growth and flower production.

We don't water the dahlias until we see them coming up, and you shouldn't need to if your soil is anywhere near moist when you're digging. (But again, that can vary depending on where you are.) We don't stake at all—that's one of the biggest things we do differently than other commercial growers.

HOW CAN YOU GET AWAY WITH NOT STAKING?!

Well we generally don't have a lot of wind in our field. The other thing is we plant clumps instead of single tubers. We plant a crown with 3-4 tubers coming off of it. We've found it gives us better flower production and it's a stability enhancer that allows us not to net. The plants get just as tall, but they have more roots going down, and we also plant them close together so they have each other as a buffer.

FOR HOME GARDENERS, IS PLANTING DAHLIA TUBERS MOTHERS DAY WEEKEND A FAIR RULE OF THUMB?

Mother’s Day is probably a good benchmark. It depends on the climate, but it’s really when your soil warms up, and danger of deep frost has has passed.

HAVE YOU MADE MISTAKES OVER THE YEARS THAT YOU'VE LEARNED FROM?

Absolutely! The biggest thing was leaving them in the ground. It worked for us for a number of years, but then we had a really bad cold spell and lost 70% of our tubers, which was devastating. Then we tried to mulch them and use plastic, and that created a rodent problem.

Another mistake was with amendments. We were doing individual nutrients, and one of them (potash) got added in a much higher dose, and all of those plants got stunted, about 1/8 of our crop. So that's why we've moved toward using an all-purpose fertilizer.

Another big thing we're still learning about is insects that we deal with on the dahlias. In the last 7-8 years, western flower thrips have really become an issue for us, and we also have cucumber beetles to contend with. We’re not certified organic, but we don’t spray, we don’t use insecticides. The cucumber beetles are really hard, we haven’t found a good solution for them, but we’ve found that the more birds we have, the better, and we do a lot of hand picking. It's interesting— they really affect the white dahlias most. We found a great predatory insect for the thrips: minute pirate bugs. They are tiny little things. We ordered them a few years in a row and now we have a fairly flourishing population that returns. 

YOU DIG YOUR TUBERS UP AT THE END OF THE SEASON, CAN YOU SHARE THAT PROCESS WITH US?

We don’t have to pull the tubers out of the ground here generally, but we choose to so we can divide them to a size we like, and to make sure we don’t lose the varieties we really need. We've also had issues with rain and rot, and rodents as well. 

We generally wait until our first frost, give them a week to cure, and then dig the tubers. But of course that changes according to the weather. Last year we had the frost and then sunny, clear days, so we had time to dig them all out by Nov. 1. But other years we've had to dig in heavy rain, which is a mess. They're muddy, so we had to spray them off, which is not ideal. If they're too wet when you store them, they can rot. You have to cure them and let them dry...but you also don’t want to get them too dry, because then they’ll shrivel.

Ideally we lift them, shake off the dirt and divide them in the fall. Once they’re dry, we store them in wood shavings in crates in our cooler. (We don't store them cold in the cooler, we just use it to hold them.) The tubers like to be around 45 degrees or so. Not warm enough for them to start waking up, but not freezing. We store the other half in our insulated box truck, and we put a heater in there if it gets really cold. I would love to just ignore the tubers all winter and assume they’ll be fine, but we do check on them about 2-3 times throughout the winter. The first time you check, you’re always nervous about what you’re going to find! Even in the insulated trailer and cooler, once they start warming up, they wake up and their eyes start to swell. Once that happens, they're ready.

WHAT ARE SOME OF THE MOST POPULAR DAHLIAS YOU GROW?

Our market is so varied, I get to grow the whole rainbow of dahlias. For the past five years, our designers have been very focused on white and cream shades, blushes, toned-down colors. Of course Dahlia 'Cafe Au Lait.' But then we've also found we're getting more interest in dark, saturated colors: deep purples, moody (not bright) oranges, jewel tones. For the farmer's markets, people want something bright and fun: reds, oranges, pinks.

We try to grow the types that we find last longest as cut flowers: balls and poms. Of course there are things you can do to prolong their vase life—use clean vases, clean water, keep them out of the sun when sitting on your table—but dahlias don't necessarily last a long time. We always let our clients know that with 'Cafe Au Lait' and other dinnerplate dahlias, you're getting 3 days of ethereal gorgeousness, and then they fade pretty quickly.