Oregon Summer Day

A young girl runs through a field of dahlias in Canby, Ore.

Three of my dahlias started blooming last week, and several more are just about to pop. For most of my dahlia growing years, I had to wait until late July for the first flowers, but who wants to wait that long?

Impatience finally got the best of me. For the last three years, I’ve started some of my favorite dahlia varieties in my small, unheated greenhouse in mid-March, and planted them out at the usual time in May. Each tuber goes in a plastic pot, barely covered in moist potting soil. The warm daytime temperatures coax the eyes to develop more quickly, giving me a jump start on the season. It won’t be long before I’ll be picking armloads of sumptuous dahlias, along with cosmos, amaranth, zinnias, and celosia.

Annual flowers like these have a single growing season to complete their life-cycles. Gardeners know that for the longest possible sequence of blooms, all faded flowers should be removed the moment they start looking shabby, or when the petals start to drop. This stymies the plant’s seed production, and tricks annuals into producing additional waves of blooms.

After flowers are cut for bouquets, they’ll look fresher longer if you can provide them with three elements. Carbohydrates are necessary for cell metabolism. Biocides combat bacteria. Acidifiers adjust the pH of water to increase water uptake.

Everyone seems to have their own recipe for providing these essentials. Mae Lin Plummer did us all a favor and tested six additives against plain water, and reported the results in the May/June 2015 issue of Fine Gardening.

She used freshly cut sunflowers, lisianthus, and celosia. Data was recorded daily for 15 days on the quality of the flowers, and rated with a number system. 2 was “good”, indicating that the flowers looked like they had just been picked. Flowers that didn’t look like they were ready for the compost pile earned a 1, indicating they were “acceptable.” Zero meant that they were wilted or shriveled so badly that they needed to be pitched. The results were surprising.

Plain water was not so bad in that the flowers looked “good”for almost a week before deteriorating rapidly.

Adding 1 tablespoon of Listerine per quart of water as an antibacterial gave similar results. When 1 tablespoon of sugar was added to a quart of water, the flowers did well overall until Day 6, when the leaves began to wilt, while the flower petals themselves held up longer. Similar results were gained by placing the flowers in a solution of 1 tablespoon sugar and ½ teaspoon of bleach per quart of water. While the overall quality of the flower petals was good, and the water in the container remained clear, the leaves began to blotch and spot.

The worst overall results were from using a solution of 1 tablespoon sugar and 2 tablespoons vinegar per quart of water. Flowers started to wilt by Day 2. Stems started turning brown at the bottom, and the damage quickly spread to the flower.

The best home remedy turned out to be 1 part lemon-lime soda to 3 parts water. The author speculates that the sugar provides food to the flower, while the citric acid prevents bacteria build-up. The flowers were acceptable for an average of 7-14 days. Except for the fact that the water was cloudier at the end, these results rivaled those of the winner (drum roll, please).

Flowers treated with FloraLife Flower Food 300 lasted the longest and looked best (9-14 days), and the water remained clearest. While the ingredients in FloraLife are proprietary, the company’s website lists “a sugar for nutrition, an acidifier to lower the pH of the water, and a class of compounds called stem absorption enhancers.”

The study did not compare the merits of a variety of commercial floral preservative brands. Do they all give comparable results, or is FloraLife superior?

While dahlias are not a particularly long-lasting cut flower, I learned from Swan Island Dahlias that their vase-life can be increased by placing cut stems in hot water (160-180 degrees) that’s allowed to cool, before placing the dahlias in fresh water and floral preservative.

Will I use the lemon-lime soda solution or FloraLife in every vase I fill with flowers? Probably not, especially if they’re destined for nothing loftier than my kitchen counter. But will I use one of them if I’m giving flowers as a gift, or if I want my flowers to hold up for a special event?

It’s absolutely worth the extra effort.