Hydrangea serrata 'Blue Billow'

The parents of this lovely Hydrangea serrata (Lacecap) variety were found growing on the wooded slope of a Korean mountain, which explains Blue Billow's exceptional hardiness. This shrub produces delicate clusters of light blue flowers that last for several weeks in early to midsummer (July here in Connecticut), turning a stunning deep crimson as they age. Fall foliage is an attractive shade of burgundy. Excellent in a shady border with Ferns and Astilbes. 'Blue Billow' is a reliable bloomer through Zone 6, and adventurous gardeners in Zone 5, where flowering occurs 3 or 4 years out of 5 may also wish to give it a try. It performed well at our nursery in full sun. Blooms on old wood.

For this Hydrangea, you can change the color of your blooms by using one of our soil additives, flowers will generally be more blue when grown in acid soils, and pink when grown in alkaline soils.

Hydrangea is a valuable genus of some 100 species of shrubs and vines grown for their large and very showy flower heads. Hydrangeas are at their best in summer and fall—a quiet time for most woody plants—and are worth having for that reason alone.

For more information on Hydrangea care, click on Growing Guide.

We want our customers to receive strong, healthy plants that are ready to thrive in their gardens and homes. Here's what we'd like you to know about our shipping practices.

Delivery Timing

We aim to deliver your plants at as close to the proper time for planting in your area as possible. To do so, we consider the USDA Hardiness Zone to which we're shipping, current and forecasted weather at the destination and along the shipping route, and whether your plants are ready for transplant.

In spring, we ship first to the warmest regions and move north as planting conditions improve. For fall deliveries, we begin with the coolest regions and work south. We frequently adjust shipping schedules when extreme weather could put plants at risk while in transit or soon after arrival.

Because different plants reach readiness at different rates and are weather-sensitive in varying degree, a single order may be delivered via multiple shipments. Plants sold as part of a collection, or that are otherwise meant to arrive together, will be shipped together. Please contact our customer service team with two weeks' advance notice if you anticipate being away at the expected time of delivery.

Tracking information for each package is delivered via email.

Plant & Container Sizes

We deliver plants in various sizes and stages of growth, and the product detail pages of our website indicate the form and/or pot size in which the plant will be delivered. Pot sizes range from 1 pint to 1 gallon and larger. Many perennials, roses, shrubs and vines are delivered bareroot - that is, not in a container at all. Bulbs and tubers are generally delivered bareroot and fully dormant. We choose container sizes and delivery methods based on how each plant grows best, how we can minimize transplant shock, and how to minimize unnecessary bulk/weight in shipment.

Caring for Your Plants Upon Arrival

It is important to acclimate greenhouse-grown plants to life outdoors. All plant shipments include simple instructions for handling your plants upon arrival. Further how-to information, including planting instructions, is available on each plant's product page.

Latin Name Pronunciation: hye-dran'jee-uh

Growing H. serrata

Light/Watering: Most varieties thrive in full sun in the North, but in the South require afternoon shade. Moist soils that do not dry out are best; do not plant in hot, dry, exposed sites. Mulch to conserve moisture and buffer soil temperatures.

Fertilizer/Soil and pH: In some varieties, flower color is determined by the pH of the soil; at low pH (acid soils) flowers will be blue and at higher pH, flowers will be pink. Generally, a pH below 5.0 results in deep, vivid blues and as the pH rises the flowers range from blue to lavender to mauve to a vivid deep pink at pH 7.0 (neutral). The pH determines the availability of aluminum in the soil; this element is more readily available in acid soils, and this availability results in the blue flower color. Since phosphorus ties up aluminum in soils, using a fertilizer low in this nutrient will aid in attaining blue flowers. If pink flowers are desired and your soil is acid, simply add lime to raise the pH and use a balanced fertilizer. Aluminum sulfate will lower pH if blue flowers are desired.

How to test your soil?

We recommend that you visit your local Cooperative Extension Service to find out about soil testing in your area. Follow this link for a directory of institutions involved in the Cooperative Extension program.

Pests/Diseases: None serious. Occasionally powdery mildew will infect the foliage, especially in humid areas with poor air circulation. Treat with an appropriate fungicide if the problem is serious, and be sure to rake up and destroy all fallen foliage in the autumn.

Pruning: Little pruning is needed, but if shrubs grow too large, cut back stems by about one-third by the end of August. In spring, only prune out dead wood. Most Hydrangea serrata varieties bloom on old wood. H. s. Tuff Stuff™ is a variety that blooms on both old and new wood. If no fall pruning was done, stems can be cut back by one-third in spring if necessary—but this will sacrifice the bloom on the old wood and shrubs will not flower until late summer.

Transplanting: Young plants may be transplanted when dormant in early spring; larger tree-form varieties are difficult to move once established, but it can be done. Prune top growth after transplanting to reduce water loss.

End of Season Care: Rake up and destroy any fallen foliage that was infected by powdery mildew or other fungi.

Calendar of Care

Early Spring: Prune out any dead wood from all varieties. Check soil pH and adjust up or down if needed for desired flower color. Feed plants with a fertilizer high in phosphorus (such as 15-30-15) to encourage blooms. Complete any transplanting before leaves unfurl.

Mid-Spring: Mulch plants after soil has warmed to conserve moisture and buffer soil temperatures. Watch for powdery mildew and treat as needed.

Summer: As soon as blooms fade, remove old flowering stems. If needed, prune as indicated above by the end of August.

Fall: Remove and destroy any fallen foliage that was infected by powdery mildew. If not pruned in spring, plants can be shortened, or pruned back to the ground.

For more information on growing Hydrangeas, click here.

SHOP ALL HYDRANGEAS

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Should you have any questions about how our guarantee applies to a particular product or circumstance, our customer service team will be happy to help – please contact us at (800) 411-6159 or custserv@whiteflowerfarm.com.