Twenty years ago, northern gardeners didn’t consider using Hydrangea macrophylla, commonly known as bigleaf hydrangea, in their gardens. While many cultivars were crown hardy in USDA Zone 4, bigleaf hydrangea formed flower buds in autumn, which usually froze over the winter, resulting in plants with no flowers in early summer.
That all changed in 2004 with the introduction of the Endless Summer® hydrangea by Bailey Nurseries and the multiple cultivars of the Endless Summer brand. While the original Endless Summer has been an unreliable bloomer in northern gardens, the more recent introductions have been hardier and more reliable blooming plants in our gardens.
In 2019, the fifth cultivar in the series—called Summer Crush®—was introduced. Developed by Bailey Innovations, the Georgia-based breeding company of Bailey Nurseries, Summer Crush was extensively tested before being introduced, not only in northern gardens but across the country.
Summer Crush is a shorter, more stout and heavily branched Hydrangea macrophylla with thick, dark foliage that resists mildew and wilting from summer heat. One of its parents is Endless Summer BloomStruck®, which has been reliably hardy in zone 4. Gardeners in zone 3 can use Summer Crush beautifully in containers, and if you overwinter it carefully, it just may come back for you.
The color of Summer Crush makes it unique in the series. In Minnesota’s naturally alkaline soils, the color is a rich raspberry. In acid soils, it is a gorgeous purple color, but you will find it sold in the garden centers in the raspberry color. If you want to try to achieve the purple bloom, you will need to acidify your soil. For that, I recommend soil sulphur rather than aluminum sulphate so that you don’t burn the roots.
Reaching a mature height and spread of 18 to 36 inches, this is a wonderful plant not only for container culture but for garden or foundation planting. It is best planted in evenly moist soils (use some wood mulch around it) where it receives sun in the morning through early afternoon. If you can give it some relief from the hot afternoon sun, that is best, but I’ve seen Summer Crush perform well in full sun, with adequate moisture. There are no major insects or diseases to worry about.
Like other varieties in the Endless Summer series, Summer Crush is remontant, which means it forms flower buds on both old wood in autumn and new wood in spring. Depending on how much snow we get and how cold the winter is, we can sometimes lose those fall-formed buds to cold, but be assured that it will create new flower buds in early summer. It will then throw out flowers throughout the season.
Many readers of Northern Gardener know that I work for Bailey Nurseries and, full disclosure here, I am responsible for product development. The testing and introduction of Summer Crush has been an important part of my duties over the last six years. I have had a Summer Crush in my yard in South St. Paul for six winters and can say with confidence it has come through every single winter (even 2019!) and has bloomed consistently for me each year. I have tested it in containers on my back deck and it is just a great plant in a pot. While I understand some of the disappointment in the original Endless Summer, I feel that our breeders have made huge strides in improving the species and creating varieties that work for northerners. When I speak to garden clubs and master gardener groups, I always recommend that northern gardeners use either BloomStruck or Summer Crush for consistent hardiness and bloom.
You’ll find blooming Summer Crush hydrangea in local garden centers in spring 2020.
Debbie Lonnee works in the horticulture industry and gardens in South St. Paul.