How to Grow and Care for Strawberry Sundae Hydrangea

Strawberry Sundae hydrangea

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Strawberry Sundae hydrangea is a cultivar that stands out from the rest of the panicle hydrangea varieties. As a multicolored bloom, the Strawberry Sundae hydrangea flowers are initially creamy white, then change to light pink, and finally mature to strawberry red in late summer. You’ll get to enjoy the various stages of the bloom more than once because Strawberry Sundae blooms from mid-summer to fall. With a maximum height and width of about 4 feet, it is a compact hydrangea that fits in small spaces and a medium to fast grower. Strawberry Sundae is also one of the most winter-hardy cultivars. 

Like all hydrangeas, the plant is toxic to humans and pets.

 Common name  Strawberry Sundae hydrangea, Sundae Fraise hydrangea
 Botanical Name  Hydrangea paniculata ‘Strawberry Sundae’ (‘Rensun’)
 Family  Hydrangeaceae
 Plant Type  Shrub
 Mature Size  4 to 5 feet tall, 3 to 4 feet wide
 Sun Exposure  Full, partial
 Soil Type   Well-drained, moist
 Soil pH  Acidic, neutral
 Bloom Time  Summer, fall
 Flower Color  White, pink
 Hardiness Zones  4-8 (USDA)
 Native Area  Cultivar, no native range
 Toxicity  Toxic to humans, toxic to pets
Strawberry Sundae hydrangea

Salicyna / Wikimedia Commons / CC BY-SA 4.0

Strawberry Sundae Hydrangea Care 

Light

For the best bloom, the shrub needs full sun. If it gets less than six hours of sunlight, it will not only bloom less but also get leggy. At the warmer end of the zone spectrum (more towards zone 8), a location with direct morning sun is better than a site with hot afternoon sun. 

Soil

The soil should be rich and well-drained, with a neutral or slightly acidic pH (between 5.8 and 6.2). Unlike other hydrangeas, the color of Strawberry Sundae is not affected by the soil pH.

Water

The shrub needs about 1 inch of water per week, either from rainfall or irrigation. In hot weather, the plant requires additional water to prevent it from wilting. Hydrangea roots are shallow, which means that water reaches them quickly, but it also means that they are prone to drying out faster because they are so close to the soil surface.

Temperature and Humidity

This cultivar is winter-hardy down to zone 4. High humidity can lead to fungal diseases, especially if it is not thinned sufficiently by pruning to allow enough air flow and moisture from rain or morning dew on the foliage cannot dry quickly. 

Fertilizer

If the hydrangea has been planted in rich soil, it won’t need much fertilizer. Working two shovelfuls of compost into the soil in the spring is often enough. For soil that is less rich, apply a slow-release, balanced fertilizer each spring after the plant has come out of dormancy. Do not fertilize after late July so the plant can enter dormancy and there won’t be any new growth that is susceptible to cold.

Other Panicle Hydrangea Types

There are numerous other panicle hydrangea cultivars, including: 

Pruning

When it comes to pruning your hydrangea, it is important to know that Strawberry Sundae, like the other panicle hydrangeas, blooms on new wood. The best time to prune it is in the late fall. Wait at least two weeks after the plant has dropped all its leaves. You can also prune it in the early spring just before the plant starts to leaf out. 

Propagating

Strawberry Sundae is a trademarked, copyrighted cultivar and propagation by any means is prohibited. Note that the flowers of this cultivar are sterile, so it won’t produce any seeds.

Strawberry Sundae hydrangea

Salicyna / Wikimedia Commons / CC BY-SA 4.0

Potting and Repotting

Due to its compact size, Strawberry Sundae is a hydrangea cultivar that is well-suited to be grown in containers. Choose a pot at least 16 to 24 inches wide, with large drainage holes. Since the plant remains outdoors year-round, use a frost-proof container, such as wood or plastic. Clay or ceramic pots are prone to splitting and shattering in below-freezing temperatures.

Fill the pot with potting mix and keep it well-watered. Potted plants will need more frequent watering and fertilizing about once a month during the growing season. Similar to in-ground hydrangeas, do no fertilize after late July.

When the roots have reached the sides of the container after a couple of years, repot it in a larger container with fresh potting soil, or root-prune it and repot it in the same container with fresh potting mix. 

Overwintering

Strawberry Sundae hydrangea that has been planted in garden soil does not require winter protection other than a thick layer of wood mulch around the plant to insulate the shallow roots from the cold.

Container plants are a different story; their roots are exposed and need to be protected against the cold. There are several ways to do that. As the container is likely rather large, the best option is to create an insulation silo around it, or move it to a sheltered outdoor location. 

Common Pests & Plant Diseases 

Strawberry Sundae can be affected by several diseases, including bacterial wilt, bud blight, leaf spot, powdery mildew, and rust. As always, a healthy plant is less prone to diseases and good air circulation within the plant and neighboring plants. Ample spacing is crucial so disease won’t spread as easily.

Aphids and mites might attack the plant. If you detect them, use neem oil to prevent it from turning into an infestation. 

Strawberry Sundae hydrangea

Salicyna / Wikimedia Commons / CC BY-SA 4.0

How to Get Strawberry Sundae Hydrangea to Bloom

The three most common reasons why Strawberry Sundae does not bloom are lack of light, improper pruning, and lack of nutrients or nutrient imbalance. If the plant does not get at least six hours of sunlight, bloom will be poor. If it’s an in-ground plant, moving it to a different location is not the only option; cutting back surrounding vegetation can also increase sun exposure.

Too much nitrogen produces foliage but no flowers. The source of the excess nitrogen might not be the fertilizer you applied around the plant, it could also be runoff nitrogen fertilizer from a nearby lawn. When you fertilize the shrub again in the spring, use a bloom-boosting fertilizer that is high in phosphorus.

Pruning too late in the spring can also lead to reduced bloom because you accidentally removed developing buds. 

Common Problems with Strawberry Sundae Hydrangea

Strawberry Sundae hydrangea is generally free of issues. However, it is not unusual for Strawberry Sundae to develop some yellowing leaves in the center part of the plant, which oftentimes happens during the first season. As the plant grows, the new foliage at the top is casting shade on the inner leaves below. The lack of light leads to slowed-down photosynthesis and leaves that turn yellow and eventually drop. This temporary problem can be remedied by proper pruning the next spring to increase light exposure to all the parts of the plant.

Also, the large, pyramid-shaped flower panicles can cause the stems to droop, which is a visual annoyance to some gardeners. You can prevent this by keeping the shrub well-pruned so that the stems don’t get overly long.

FAQ
  • Why are my Strawberry Sundae hydrangeas white?

    This is normal, there is nothing wrong with your plant—the flowers of this cultivar start out as creamy white and turn strawberry red to pink in the late summer.

  • Why is my Strawberry Sundae hydrangea not turning pink?

    The change of color from creamy to pink is triggered by cooler weather in the late summer. It is likely that the nighttime temperatures in your location are still quite warm. Once the nights become cooler, you should be seeing the color change.

  • Should you cut back Strawberry Sundae hydrangea?

    Do not cut it back during the growing season, or else you will reduce the bloom. Wait until the hydrangea enters dormancy in the fall to cut it back.

Article Sources
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  1. Hydrangea. ASPCA.

  2. Hydrangea paniculata. North Carolina State University Cooperative Extension.

  3. Hydrangea paniculata 'Rensun'. Missouri Botanical Garden.