Question: Can you help me with some information about the care of hydrangea plants⢠Mine have big blue blooms. How should I prune the plant and when⢠When should I fertilize and with what⢠When should I cut the flowers, and what's the best way to dry them⢠How do you propagate the plant?
Answer: Because you describe your hydrangeas as having "big blue blooms," I'm going to make the assumption that your plants are an old-fashioned Hydrangea macrophylla or one of its many cultivars. Be aware that the advice I'm giving is tailored to this particular species of hydrangea, so it might not be pertinent to other types.
With the exception of a few new cultivars, Hydrangea macrophylla produce their blooms on last year's growth (also known as old-wood), so those seemingly dead brown sticks you see now are holding this year's flower buds. If you cut them down, you are removing all your flowers.
It's one of the most common gardening mistakes in Western Pennsylvania. We see the brown twigs and think they are dead; we proceed to cut them clear to the ground and then wonder why there is no color in July. The best pruning advice I can give is: "Don't."
Just leave the brown stems alone. It might drive you nuts for a few months, but soon enough, the new green growth will push out and mask their presence. Then those gorgeous flowers will arrive, and all thoughts of their former manginess will be out the window and we will be smitten.
To preserve those beautiful blooms for indoor arrangements, I recommend cutting the flower stems off in their prime (if you can emotionally manage it) and using a glycerin solution found at many crafts stores. The cut stems are placed in a vase of the liquid and allowed to "drink" it for a period of about three weeks. This method is the best for maintaining the blossom's beautiful coloration.
Bunch-drying is another possibility. This method involves hanging groups of the flowers upside down in a warm, dry location for several months. However, the blooms will fade somewhat in color, and the stems will become brittle.
To maintain the health of your hydrangea plants for years to come, fertilize annually with one or two inches of quality compost spread over the soil surface around the plant. Organic-based granular fertilizers, like Plant-Tone or Revita, are another option for yearly fertilization. My hydrangeas receive nothing but a top-dressing of compost each season, and they do beautifully. Occasionally, a late freeze will damage the buds, so some gardeners wrap the plants in burlap or landscape fabric each autumn and uncover them in early May. This isn't necessary, but it might provide added winter protection.
Propagating Hydrangea macrophylla is fairly simple using a method called layering. In late summer, select a long branch and, using a clean, sharp knife, make a shallow, inch-long slit on the bottom side of the stem about four to six inches from the end of the branch. Dust the cut with rooting hormone (available at most local garden centers), then bend the branch so that the slit is in contact with the soil. Pin the stem to the ground with a piece of cut wire, or mound soil on top of it to hold it in place.
By the following summer, roots will form where the stem touched the soil. That autumn, cut the branch right where it enters the soil and carefully dig up the newly rooted plant. Move it to a new shady spot in the garden, and work plenty of organic matter into the area during planting.
Horticulturist Jessica Walliser, co-author of the new book "Grow Organic," can be heard from 7 to 9 a.m. Sundays on KDKA Radio's "The Organic Gardeners." You also can find her teaching at Phipps Conservatory and Botanical Gardens, where she has been a faculty member for more than 12 years.
Send your gardening or landscaping questions via e-mail or The Good Earth, 503 Martindale St., Third Floor, D.L. Clark Building, Pittsburgh, PA 15212.
