Nikko Blue Hydrangea
48-72" tall x 48-72" wide. With long-lasting flower clusters and large, bright green foliage, ‘Nikko Blue’ provides an eye-catching accent in entry gardens and patio plantings. The vibrant blooms last for months, providing texture well into autumn even after their color fades. Cut a handful of flowers for a luxurious bouquet. ‘Nikko Blue’ is also ideal for dried arrangements, holding color well when dried properly. All that lush foliage makes for a thirsty shrub so keep plants well-watered and protect from drying winds. Provide a layer of mulch year-round to conserve soil moisture and regulate root temperatures. Plants seldom require pruning. If needed, wait until after flowering to prune as ‘Nikko Blue’ blooms on old wood. Weak or winter-damaged stems can be removed in late winter or early spring before growth resumes. No serious insect or disease problems.
Hydrangea shrubs are native to the US and Asia and produce showy flowers throughout the summer season. There are many varieties available, each showcasing differing bloom colors, flower shapes, overall heights/spreads, levels of winter hardiness, and abilities to be grown in containers.
What does "Blooms on old/new wood" mean and what does that have to do with winter?
Some hydrangeas produce buds that will turn into flowers on old wood (also called "last year's growth"), while others produce blooms on new wood (aka "this year's growth") and still others will flower on both old and new wood. This detail is especially valuable for cold-climate gardeners who may be apt to lose some of their hydrangea branches to breakage from heavy snow and ice, or who may see developing buds killed off by late spring frosts.
For these gardeners, losing old growth branches and young buds could mean missing out on hydrangea flowers the following summer. Choosing a variety that blooms on new wood (or both types of growth) is extra insurance; it means that regardless of your winter and late-spring weather, you can still count on your shrub to produce flowers come summer.
Likewise, warm-climate gardeners who choose varieties that only bloom on new wood, will have to make it a point to prune their hydrangea shrubs in order to encourage new buds to form. A simple task for sure, but one that needs to be remembered.
What does "Bloom color depends on soil type" mean?
The color of most hydrangea blooms are directly tied to the mineral make up of your soil and its overall pH. To really see bold colors, you'll have the best results when planting in containers, which will allow you to create your preferred soil conditions at planting time. Although soil pH can be changed directly in the garden bed, it often takes more than one season to see results. The color of native Smooth hydrangeas (Hydrangea arborescens) cannot be changed.
Acid soils (with a pH below 7) produce purple-to-blue blooms, with the brightest blue blooms resulting from the most-acidic soils. To coax your hydrangeas into producing blue blooms, you can amend your soil with sulfur, or mulch your plants with a pine and/or cedar needle mulch.
Alkaline soils (with a pH above 7) produce pink blooms. The more alakaline (or sweet) your soil is, the deeper pink your blooms will be. This can be achieved by adding lime around your planting area. It is, however, more difficult to turn hydrangea blooms pink because as a general rule, most plants struggle to be healthy in soils with a pH above 7.
Many hydrangeas today are available in a range of heights and bloom cycles, regardless of their overall type. For example, you can find Mopheads that bloom on new growth and Panicles that are container-friendly.
Mopheads: (Hydrangea macrophylla) The most well-known (yet least cold hardy) hydrangea, Mopheads are known for their oversized blooms that come in two flower types - Lacecaps and Pom-poms. Also known as "Bigleaf" hydrangeas, the foliage on Mopheads is quite enormous and delivers a lot of greenery to the garden.
Panicle: (Hydrangea paniculata) Huge, cone-shaped blooms and excellent cold hardiness are the hallmarks of the Panicle hydrangea. Their arching branches and plentiful blooms also tolerate more sun than other varieties.
Smooth/ Snowball: (Hydrangea arborescens) Also known as "Wild" Hydrangeas, these shrubs are native to the eastern US - and while their color cannot be altered by changing soil pH, their blooms tend to turn a pale green as fall approaches.
Mountain: (Hydrangea serrata) More compact than Mopheads and presenting dainty lacecap blooms and smaller leaves, these hydrangeas are native to the mountains of Korea and Japan where they're known as 'Tea of Heaven'. They're known for a slightly weeping shape and a long season of blooms.
Oakleafs: (Hydrangea quercifolia) Native to the eastern/southeastern US, Oakleafs have deeply-lobed foliage that changes color dramatically in autumn. Very cold hardy with showy, elongated blooms.