The Future in Hydrangea Hybrids
In an interview with Dr. Dirr, we asked "What is the future in Hydrangea macrophylla hybrids?"
We’ve figured out the reblooming, and now we have to get disease resistance. If we can do that for gardeners, we all win. Most of the leaves fell off our rebloomers this year (2018) because of Cercospora infection.
What I’m looking for is new genetics. If we keep doing the same thing, we’re like a breeding cul-de-sac, going round and round in a dead-end, and we’re never going to add any new traits. So we know we’ve got reblooming genes. We have pink hydrangeas, we have blue, we have lacecap. We’ve got a little bit of white. I went back and purchased or secured cuttings of many old French hybrids. Some date from 1880. Many date from 1905 or 1910 from the French breeders like Lemoine and Mouillere. These varieties have some of the biggest flowers and the thickest foliage you can find. Some of these have been around for over a hundred years and are still outstanding plants.
We’re looking for mildew resistance in some of these older hybrids, particularly resistance against Cercospora, which looks like measles on the leaves. This is especially a problem with overhead watering. If you’re going to breed for mildew resistance, what are you going to use? ‘Veitchii’. And we found one called ‘Greenmantle’, which has a froggy looking flower, a big mophead. ‘Greenmantle’ turned out to be disease-resistant, and it has these big green leaves and reddish fall color, thick green sepals with pink spots like teardrops. Another old French hybrid, one of the best, is ‘Ami Pasquier’, which has magnificent flowers and great fall color.
The genetic traits from some of the old hybrids are going to give the next great hydrangea introduction, but it might take multiple years. You cross them one year, collect the seed typically in the fall. Sow it in January, February, and March. Transplant your little cells in April-May. If the reblooming gene is there, you’ll have flower in the first year. If you’re doing a tree, it takes forever, but some of these shrubs, not so long. Hydrangeas are good to work with.
The traits we’re looking for are foliage color, intriguing flower color or a flower that is unique, maintenance of that flower with an ageless or antique-like shade through the summer and the fall, great fall color, and disease resistance. With all this, we’ve got pretty much the whole package. And who knows how long I have on planet earth, but that’s what we’re shooting for. You have to believe and you don’t just quit—I’m not gonna quit!