I get asked all of the time what my favorite flower is and answering always feels a little like singling out a favorite child. In truth there really are no favorites, just preferences at a given moment depending on circumstances like the mood that day, what’s peaking in the garden, the weather and so on.
During the long, hot summer stretches I often dream about them, counting to fives, rubber banding their stems and placing them into water. Over and over again. Many late summer days are spent entirely in the dahlia field, from sun up to sunset harvesting and bunching, driving truckloads back and forth to the cooler. On dahlia harvest days we are all ready for the change of pace and welcome the monotonous, beautiful, steady task that it is.
We’ve tried numerous approaches and techniques to growing our dahlia crops over the years. Here I’ll share what all of that trial and error has boiled down to but please keep in mind, this is what works for us, in our climate and based on our own personal production goals. We have severely limited space so must grow our plants closer together than we would if there were huge rolling fields at our disposal.
We also grow our flowers organically, so I won’t be recommending a bunch of chemicals but instead what we do to preventively combat insects and disease. Some of it may sound a bit “woo-woo” but the approach has worked very well for us and I think it might for you too. If you have any tips or tricks that you’d like to share (organic or not) feel free to leave them in the comments section below. It’s always nice to hear what others are doing all around the world.
90% of our dahlias are grown out in the open field. Our little plot is situated on top of a sandbar, literally. If you dig down just a foot, you’ll find silver beach sand, so we rely heavily on large doses of compost for fertility and thick mulches to help retain moisture through the drier parts of the season. We generally begin field planting about two weeks after our last frost date (4/25) with the process normally consuming the early part of May. Prior to planting all beds are amended with 3-4” of compost, rock phosphate, a little lime and a general organic fertilizer.
This mix is tilled in and then tubers are placed roughly a foot apart down the row, with two rows per three foot wide bed. Dahlias need a lot of water throughout the season. We run three lines of drip irrigation per row and then mulch over the top of it with a thick layer of leaves or dry grass clippings to help keep the water from evaporating. While this process is very labor intensive, once the tubers are in, dripped and mulched we do very little to them for the remainder of the season.
When sprouts begin to emerge, we go through and pull back the mulch from around the crowns. Once the plants reach rough 12″ we give them a hard pinch (snip out 3-4″ of the growing center) which encourages low basal branching, increased stem count and overall stem length.
We then start applying a bi- weekly doses of compost tea (with added kelp, rock powders and fish emulsion) to promote strong growth and help combat disease. T-posts are placed every ten feet on the outside of the beds and a double layer of bailing twine is attached to corral the bulky plants. In past seasons we’ve used tenax flower netting to help support plants but getting it off at the end of the year was a nightmare so we switched over to the twine.
For big fluffy, fragile blooms like those of the dinner-plate group, we’ve recently changed over to growing them indoors. This tiny tweak has made a world of difference in both productivity and stem length, but flower quality has also shot through the roof! Tender monsters like the Cafe au Lait’s really benefit from being out of the weather. Our plants reached over 7ft. inside the hoop-house and that was with twice a week harvesting!
Next season the plan is to use a sturdier support system (wire mesh instead of the twine) to help corral their incredible bulk. Pinching low is essential for useable flower stems on these beasts! Trying to get a dahlia with a stem as thick as a broom handle into a bridal bouquet or centerpieces is a nightmare. Our hoop-houses are unheated but with the extra insulation we were able to tuck tubers into the beds by mid March.
Insect pressure varies from season to season. Some years aphids come in abundance, other years like last thrips are a big issue and earwigs, those little bastards are always lurking, ready to chomp the perfect blooms. We’ve found that the healthier the plants, the less insect pressure we experience, so we do a lot of work to keep plants healthy and well watered throughout the season. Just like the human body, the stronger our immune systems, the easier time we have fighting off intruders.
In really extreme cases of aphids we have resorted to a few application of insecticidal soap to knock back the population. Safer brand makes and OMRI approved concentrate that you can find at most garden and hardware stores. Because of on going western flower thrip pressure, we’ve stopped growing white dahlias in the field and instead have better luck with them indoors. I’ve read about a few OMRI approved options that we might test out in the near future but so far, nothing has been very effective.
In the hoop house especially, earwigs wreak havoc and we’re still trying to find a good solution. Someone suggested last year that laying out pieces of plastic irrigation pipe with one end taped off would lure them in. Then in the morning you sweep through the patch and empty the pipes into a bucket of soapy water. We got so busy last season that I didn’t give it a proper go but am determined to try it again. There’s nothing more heartbreaking than seeing dozens of Cafe au Lait blooms chomped into bits!
While dahlias aren’t a terribly long lasting cut flower, their brilliant colorful blooms make up for their fleeting existence. The trick for longest vase life is keeping them well hydrated from harvest to the end consumer and to cut them from the plant at the proper stage. We harvest our patch every three days, rain or shine and never leave a single ripe flower on the plant. This protocol ensures that every harvest day is efficient because we aren’t having to examine individual blooms for signs of imperfection.
In the past, when we’ve skipped a harvest or delayed it by a few days, we end up spending twice the amount of time in the patch sorting and grading flowers. What a nightmare! The three day rule has changed everything and now we can comb the patch, almost without looking because every flower is at its prime and in perfect condition.
We cut straight into cool water, no preservative and the flowers are quickly shuttled into our 38-40* cooler for at least 12-24hrs. before heading out to customers. This approach gives a solid week of vase life and we’re consistently told by our buyers that our dahlias last longer than any others they’ve tried.
When I asked our friends Tony and Denise from Bare Mountain Flowers in Oregon what they do for the best vase life they shared, “We harvest early in the day before noon and put all the stems in a solution using Chrysal Gerbera Chlorine tablets. We use 1 tablet per gallon water that has OVB hydrating solution. The flowers are left in the hydrating solution for 2 hours in our cooler and then transferred to a fresh container with one more chlorine tablet per gallon of fresh water. We use no flower food as we are typically moving the flowers to market within 24 hours of harvest. Once in the vase we do recommend use of a basic flower food.”
Bob Wollam from Wollam Gardens in Virginia also chimed in with his secret recipe,”We cut our Dahlias into hot/warm water in the field and then again into hot water with a Chlorine pill and Chrysal #2 in the packing shed. We then try to hold them for 12 hours in the cooler at 38 degrees before taking to market.”
Tuesday we’ll dive into digging, storage and dividing techniques plus my favorite sources for tubers here in the states! If you have sources in Canada the UK, AU or NZ you love, leave their info in the comments below and I’ll happily add them to the list.