North Region Garden Tips and Blog: Hydrangeas

Before you run out to purchase the most alluring variety of hydrangea you see, take a moment to plan where it will be planted, what conditions it will experience and what type of plant you want. Most hydrangeas like a little afternoon shade, but need at least 4- to 6-hours of sun to flower best. This is particularly true of the big leaf (H. macrophylla) and mountain (H. serrata) hydrangeas. Others, such as the panicle hydrangea (H. paniculata), can take sun all day. Our, 'Fire Light^®' panicle hydrangea is growing on the Southwest side of our house and looks fabulous. Hydrangeas love well-drained soil, but also moisture. That's why they have “hydra” in their name. The bigleaf hydrangea tends to flop in hot sun with lack of moisture, while the smooth hydrangeas (H. arborescens) and panicle hydrangeas are more tolerant of dry soils.

Size is also important. Some panicle hydrangeas, for example, can grow over 12 feet tall. Make sure you have enough space for your favorite variety. If you need dwarf varieties to fit into smaller spaces, there are some great choices. Hydrangea arborescens Invincibelle 'Mini Mauvette^®' has dark pink blooms and only grows 3 feet tall and wide. It's a low maintenance darling in the landscape. 'Wee White' is another Invincibelle variety with white flowers and grows only 1- to 2-feet tall and wide. For panicle hydrangeas, try 'Little Quick Fire'. Its white flowers turn to pink and red in fall and it only grows only 3- to 5-feet tall. For a bigleaf hydrangeas try 'Wee Bit Grumpy^®'. It has purple flowers and only grows 2 feet tall.

For hydrangeas that are native and good pollinator plants, grow any of the smooth (H. arborescens) and oakleaf (H. quercifolia) varieties. I like 'Gatsy Pink^®' oakleaf hydrangea for its showy white turning to pink flowers and beautiful, burgundy, fall foliage color.

If your bigleaf hydrangeas (H. macrophylla) aren't producing lots of summer blooms, try reblooming varieties or the mountain hydrangea (H. serrata) such as 'Tuff Stuff^™'. Unlike the bigleaf types that are native to coastal Japan and Korea, the mountain hydrangeas are native to the cooler mountains. This means the flower buds are more cold tolerant and more likely to overwinter without damage.

To get the most flowers consistently from your hydrangeas keep them well watered and mulched with wood chips and pruned properly. Most hydrangeas don't need lots of pruning, but if you do prune, it's important to do it at the right time for each type. Prune hydrangeas that bloom on new growth, such as the panicle and smooth hydrangeas, in late winter, cutting back these plants by up to 1/3^rd.  Prune bigleaf, mountain and oakleaf hydrangeas in summer after the first flush of blooms have finished. Just remove dead blossoms and errant branches. These bloom from flower buds formed in late summer, so don't prune a lot or now. The flower buds on these hydrangea types also benefit from late winter protection. Lay floating row covers or bed sheets over them plants when a late spring frost is expected.