How to Grow and Care for Endless Summer® Pop Star® Hydrangeas

Endless Summer® hydrangeas were introduced in 2004, and were lauded as cold-hardy, disease-resistant bigleaf hydrangeas with prolific blooming habits. With these new hardy hybrids, gardeners have had more options for growing colorful bigleaf hydrangeas.

The new Pop Star® cultivar is a lacecap bigleaf hydrangea in an easy-care compact size. It is cold hardy to USDA zone 4, and comes in blue but the flowers can be turned pink with alkaline soil. The small size makes it a good choice for a patio container.

Pop Star Hydrangea Care

The Pop Star hydrangea is relatively easy to maintain: here are some basic tips for care.

• Plant in a partial shade site.
• Add organic matter (compost) when planting to ensure good drainage.
• Water well after planting and for 2 to 3 weeks until established.
• Feed with a balanced 10-10-10 fertilizer in early spring and late summer.
• Prune in early spring, or late autumn after flowering has stopped.
  

Light

This new cultivar blooms in partial shade, so a sun-dappled shady area of the garden is a good spot for it. It would also do well in an area with several hours of morning sun, but afternoon sun in the summer may prove too hot and strong for this shade-loving hydrangea.

Because of its compact size, you can also plant this shrub to get more or less sunlight based on its location and proximity to trees or taller shrubs. You can also try growing this small shrub in a container, giving you flexibility for its location. Observe the movement of sunlight in your yard through the seasons to determine the best spot.

Soil

The main factor to consider when growing macrophylla hydrangeas is whether you want to amend your soil to affect the bloom color. Acidic soils will usually yield a blue flower, whereas alkaline soils produce a pink flower.

To make soil more acidic, add some aluminum sulfate or wettable sulfur to your soil area. Other natural amendments such as peat moss, pine needles, or coffee grounds can also raise soil acidity slightly. To make soil "sweeter" or more alkaline, use powdered lime or crushed limestone.

Water

Water your Pop Star hydrangea well after planting, and water regularly for 2 to 3 weeks until it is established. After that, water as you would the rest of your garden, making sure it gets some additional water if there's a lack of rain for more than a few days.

Temperature and Humidity

This cold-hardy shrub will perform best within the growing zone range of 4 through 9 (USDA). If your summer days tend to get a bit hot (as happens more often in the Northeast), plant your Pop Star hydrangea where it will get morning sun instead of afternoon sun. Temperate zone humidity should not bother this sturdy plant. If you note any powdery mildew, this is more likely due to lack of air circulation, as opposed to too much humidity.

Fertilizer

Your Pop Star hydrangea will likely have some fertilizer granules in the soil in the container when you purchase it. Therefore, wait until your shrub has been established for several months to a year before applying any extra fertilizer. (It's always best to perform a soil test before adding any fertilizer to ensure you aren't overfertilizing.)

A regimen of organic, balanced 10-10-10 NPK fertilizer (which provides equal amounts of nitrogen, potassium and phosphorous) is recommended for the Pop Star hydrangea. This can be applied with plenty of water in early spring, and, if desired, again in early August before reblooming occurs. Don't fertilize after mid-August to allow the plant to prepare for its winter dormancy.

Types of Endless Summer Hydrangeas

• BloomStruck® Bigleaf Hydrangea: This cold-hardy hydrangea has a beautiful range of colors across its blooming season. It grows up to 5 feet tall and 3 feet wide. The color show begins with pale blue, and later includes shades of purple, pale green and dark burgundy. The dark red stems accent the shifting colors. This is one of the most colorful mophead hydrangeas available.
• Blushing Bride Bigleaf Hydrangea: As the name suggests this hydrangea has white flowers that turn pale dusky pink with maturity, similar to the coloration of paniculata hydrangeas, but this is a white mophead. This hydrangea will grow up to 5 feet tall. Its color stays true regardless of soil pH.
• Twist-n-Shout® Bigleaf Hydrangea: This is a lacecap variety that grows between 3 and 5 feet tall. The flowers have vivid colors that range from deep pink to periwinkle blue, depending on soil acidity.

Pruning Pop Star Hydrangeas

The best time to prune bigleaf hydrangeas is in late autumn (late November or early December) after blooms have begin to fade. You can also prune lightly in early spring but be mindful of any buds that have begun to form. These shrubs should be pruned lightly just to maintain shape, or to remove dead or broken branches.

Growing Pop Star Hydrangeas in Containers

These compact shrubs do very well in containers on your patio. Make sure you choose a container that will give the roots some space to grow, and repot the hydrangea every other year, or as it begins to outgrow its container, and refresh the soil each time you repot it.

Overwintering Pop Star Hydrangeas

To protect your hydrangea's roots during a cold winter, put a 3- to 4-inch layer of natural mulch (wood chips, pine straw and leaves all work fine, alone or mixed together) around the base. If your

Pop Star hydrangea is in a container, shifting it to a larger container for winter is a good idea, as the container's soil will likely freeze, which can damage the roots. It's recommended to move the container to a sheltered, slightly warmer space such as a shed, garage or basement, where it will stay cool but not freeze. Give it a small amount of water every few weeks, just barely moistening the soil, as this also helps protect the roots.

Common Pests and Plant Diseases

Although the Endless Summer hydrangeas are considered very disease-resistant, there are some pests and diseases that occasionally affect macrophylla hydrangeas. These may include leaf spot (Cercospora or Phyllosticta hydrangea), powdery mildew, bud blight, and leaf rust.

In addition, common pests that may affect hydrangeas include Japanese beetles, slugs and aphids. Most of these conditions or pests can be addressed with simple non-toxic treatments. Sufficient air circulation helps prevent powdery mildew, so when planting, leave some space around the shrub.

How to Get Pop Star Hydrangea to Bloom

One of Pop Star hydrangea's most appealing characteristics is its ability to rebloom. New buds will appear just four weeks after being deadheaded. It's tight growth habit makes the flowers, not the foliage, the focus.

Some gardeners find bigleaf hydrangeas shrubs to be somewhat challenging in the garden, and their most common issue is a failure to flower consistently. The underlying reason for lack of flowering is often that the buds have been damaged by cold temperatures, but with the cold hardiness of the new Pop Star cultivar, this shouldn't be too much of a problem.

Using a basic balanced organic fertilizer once or twice during the growing season should be sufficient. In addition to early spring and late summer (early August), you could also feed once more in early May and see if that gives an added boost to the flowers. But wait until your plant has been established for a year or so to get a sense of the timing for its blooms, before beginning a fertilizer regimen. (And it's a good idea to perform a soil test before fertilizing).