July is upon us, hot steamy days and beautiful hydrangeas are everywhere: all kinds, shades of white, pink and blue, lacy caps, oak leaves beckoning us and being celebrated everywhere. We’re bringing back a few hints on pruning them, but we hope you will just be relaxing in your hammock, keeping cool, drinking iced tea, and enjoying them.
Pruning hydrangeas on old wood
In the May Horticultural Hints, we provided information about pruning hydrangeas that bloom on new wood. Here are hints for hydrangeas, such as the following species, that provide flowers on old wood:
- H. macrophylla: Bigleaf Hydrangeas (large, rounded “mophead” balls or flat “lacecap” shapes)
- H. petiolaris: Climbing Hydrangeas
- H. quercifolia: Oakleaf Hydrangeas
- H. serrata: Mountain Hydrangeas
Varieties flowering on old wood need summer pruning right after blooming. Clean up spent flowers from last year. Remove any weak, thin, or dead stems at the base.
Check the growth size of the hydrangea when you are planting. Some can become very large. Allow enough space for growth.
Pruning reblooming hydrangeas
Another group of Hydrangeas bloom on both old and new wood.
- Endless Summer series
- Let’s Dance series
These can be deadheaded immediately after they finish blooming in summer or lightly shape them in early spring. Prune back to the first set of healthy, plump buds.
Summer care for other plants
Deadhead (pinch off) the spent flowers of perennials and trim off the flower stems. This may encourage reblooming of some plants and in general improve the plant’s appearance. Deadhead flower stalks of daylilies, goatsbeard, coral bells, daisies, bee balm, salvia, phlox and spike speedwell. Do not cut off the flower heads if you wish plants to go to seed.
As plants grow taller, lean over or crowd other plants, give them support by staking them. Many types of stakes are available in garden centers, found in garden catalogs, or just simply use branches. We have used bamboo stakes and ties for very tall plants.
Create a naturalistic look when pruning shrubs: azaleas, rhododendrons, lilacs, winterberries, viburnums, weigelas, hollies, boxwoods, and small trees such as crabapples and Japanese maples. Remove deadwood, broken and crossing branches and judiciously tip branches for shape. This will increase air circulation and space for branches to leaf out to photosynthesize and reduce the incidence of disease and pest problems.
Plantings in containers dry out much faster than plants in the landscape. Lightweight potting mediums make moving pots easier, but more frequent watering is required. Be sure to keep deadheading to keep container plants looking their best and encouraging new blooms.
Be on the lookout for poison ivy in the landscape. The oily resin urushiol is found in all parts of the plant: roots, leaves, flowers, berries, stems and vines. Be sure to wear gloves or use tools to remove and dispose of these plants. If poison ivy plants are very small, place a plastic bag on your hand to pull up the plants and then fold the plastic over the plant and dispose of it in the trash.
Never use pesticides or fungicides on your garden plants when temperatures get higher than 85 degrees. The bright sun will burn the foliage and may kill the plant.
With the heat and humidity of summer, keep a close eye on your garden plants for powdery mildew. The fungus will begin as a white dust-like covering on the leaves of your plants. This is especially true if you water with overhead sprinklers. Powdery mildew will block the sunlight from plant foliage and the leaves will turn brown and black, quickly dying. When the foliage dies, the plant is prevented from making fruit and flowers. Pick up the dropped leaves and dispose of them in the trash.
If leaves are curled and brown on the edges of your plants, the problem may be leaf scorch, which occurs when water loss through transpiration exceeds the ability of a plant to take up water through the root system. Leaf scorch can be caused by transplanting, root damage because of excavation, soil compaction, over fertilization, high soil salts, or environmental conditions. The environmental conditions include hot weather, low soil moisture, and windy conditions.
Be safe! Stay in the shade as you work in the garden on hot days. And be sure to keep hydrated.
Judy Dembsey is chair of environmental education for the Acton Garden Club.
Ann Marie Testarmata is chair of public relations for the Acton Garden Club.
Editor’s note: With the continued hot weather and low rainfall, keep an eye on the Water District website for changes in watering rules.
