Selection, Planting And Fall Care Of Hydrangeas

This is a great time to plant a few new hydrangeas in the garden. These versatile shrubs make colorful screens, focal points and combine nicely with other plants in mixed borders. Then make sure all new and existing hydrangeas receive the needed care to prepare them for the winter ahead.

Those looking for native options are in luck. Smooth hydrangea (Hydrangea arborescens), native to Illinois and much of the eastern United States, has been a traditional favorite for shady spots in the garden. Many refer to this group of hydrangeas as Annabelle-type, due to the notoriety of this variety. Smooth hydrangeas combine nicely with other shade-tolerant plants like hostas, astilbes and ferns. The large, round flowers start out green, then turn to white and eventually back to green. Annabelle-type hydrangeas will tolerate more sun as long as the soil is moist but not soggy wet.

Because these hydrangeas flower on new growth, prune them any time during the dormant season. Consider pruning them in late winter, after the worst weather has passed and before growth begins to enjoy the winter interest the dried flowers provide. Promote more sturdy growth by cutting all the stems back to 12 to 15 inches above the ground. Next, remove half of these back to ground level. The older stems provide support for new growth sprouting at the base of the plant. Or, cut all the stems back to several inches above the ground, but plants pruned this way tend to be floppier.

Panicle hydrangeas (Hydrangea paniculata) come in a variety of sizes, are hardy and require minimal care. Grow these in full sun for maximum flowering or in a partially shaded location where they will also perform well. Panicle hydrangeas prefer moist, well-drained soil but once established will tolerate drier conditions than other hydrangeas.

The large, cone-shaped flowers of panicle hydrangeas generally start white and mature to shades of pink and red. Like Annabelle hydrangeas, these reliable blooming shrubs flower on new growth. They require very little pruning to perform their best. Just remove crossing, damaged and weak stems as needed. Thinning the plants to five to 10 primary shoots will encourage larger flowers. Avoid severe pruning that can result in weak, floppy growth.

The other North American native hydrangea is the oakleaf (Hydrangea quercifolia). This shade-tolerant shrub provides four seasons of beauty. The deep green, oak-leaf-shaped leaves make a nice backdrop for other shade plants. The late summer cone-shaped flowers start out white and mature to pink and eventually brown. The fall color is outstanding, with a mixture of bronze, maroon and purple. Once the leaves drop, the exfoliating orange bark is revealed to brighten up the winter landscape.

This hydrangea flowers on the previous season’s growth. Limit pruning to crossing and broken branches and dead wood in the spring. Prune right after flowering to control the size.

Bigleaf hydrangeas (Hydrangea macrophylla) are the colorful pink and blue hydrangeas that have been mainstays of southern gardens for decades. They bloom on the previous season’s growth that is often killed to the ground by our cold winters. Repeat blooming varieties now allow northern gardeners to enjoy their blossoms. They flower on old growth if it survives, and again on new growth.

Increase the chance of an early-season floral display by allowing the plants to stand for winter. Cover them with straw or evergreen boughs for added insulation. Wait for the buds to swell in spring and remove any dead stems and dead growth above the swollen buds. Even with added insulation, the whole plant may only need pruning back to ground level.

Grow bigleaf hydrangeas in moist, well-drained soil in a location that receives full sun with some afternoon shade. The flowers will be blue in acid soil and pink in alkaline or high-pH soils like those in northern Illinois. Enthusiastic gardeners can change pink blossoms to blue by applying aluminum sulfate to the soil from spring through July. Be sure to read and follow label directions.

Improve flowering by keeping the soil moist, but not wet, throughout the growing season. Fertilize in spring with an organic nitrogen fertilizer that contains flower-promoting phosphorous that is available to the plant.

Proper care throughout the growing season is the best preparation for winter. Continue watering hydrangeas as needed throughout the fall thoroughly whenever the top few inches of soil are crumbly and moist. Wait until spring to fertilize, and then only if needed. Late-season fertilization may stimulate late-season growth that is more subject to winter injury.

Extend the enjoyment by growing a variety of hydrangeas to provide blooms from summer into fall, then cut and enjoy a few to enjoy indoors, fresh or dried.

Melinda Myers has written more than 20 gardening books, including The Midwest Gardener’s Handbook, 2nd Edition and Small Space Gardening. She hosts The Great Courses How to Grow Anything instant video series and the nationally syndicated Melinda’s Garden Moment TV and radio program. Myers is a columnist and contributing editor for Birds & Blooms magazine. For more information, visit MelindaMyers.com.

 

 

Learn more about selection, pruning and care of hydrangeas with Melinda Myers at 11 a.m., September 16, at Pasquesi Home and Gardens, located at 975 N. Shore Dr., in Lake Bluff. The event is free, and no registration is required.