June, 2017
POISON IVY FOLLOW-UP
Thank you to everyone who took the time to write in after the Poison Ivy Primer was distributed. Every year, there are many who insist that the 5-leaf plant is really Virginia Creeper and not Poison Ivy, and every year I have respectfully disagreed…until this year. A special thank you to Betty Marose, the retired University of Maryland Extension weed specialist and horticulturalist who took the time to forward to me several scientific articles concerning Poison Ivy and Virginia Creeper. My landscape contractors and I have been suffering from a ‘Poison Ivy’ rash for many years after working in areas where the 5-leaf plant was prevalent, so you can understand my reticence to accept that this is not Poison Ivy. I have since learned that Virginia Creeper contains OXALATE CRYSTALS that have been known to cause a rash almost identical to that caused by Poison Ivy. In addition, it is common to see Poison Ivy and Virginia Creeper growing side by side in the woods. As a result, I would love to find a biologist/chemist willing to test some of my plants for the presence of either urushiol (Poison Ivy) or oxalate crystals (Virginia Creeper). Meanwhile, the message to gardeners is to be cautious when working with either Poison Ivy or Virginia Creeper. If you are sensitive to one, you may be sensitive to the other as well.
For help with identification, see the photo below (courtesy of Betty Marose):
WHEN TO WATER… The cool, rainy days in May were a gift to our plants. As soon as the temperatures soar, our plants will feel the stress, and later in the summer, we will experience the August drought. As a rule of thumb, if we experience a change in temperature of 20 degrees or greater, your plants will feel stressed, and will benefit from additional water. Plants that are beneath a dense canopy or are protected by an overhang will not reap the benefits of a good rain. Be sure to give these challenged areas additional water. If you see the plant begin to droop, or the leaves to curl, then check the soil. If 2 inches below grade is dry, then provide extra water. A long gentle steady soak is better than a short drenching. You want the water to have a chance to really soak in deep before the heat of the day evaporates all of the good work you have done, so water early in the day before 10am or late after 5pm. If these time slots for you don’t seem to work, just remember that anything you do is better than nothing when your plants are stressed.
MILDEW STAINED EXTERIOR SURFACES…Has your terrace or outdoor furniture become dark with stains? Try this recipe to clean your surfaces without a lot of elbow grease. This usually has good results on masonry, wood and plastic. Also works on siding. (Courtesy of the Clemson University Cooperative Extension Service)
1 qt. Liquid Chlorine Bleach
½ cup Detergent (ammonia free)
3 qt. Water
Apply with scrub brush or long-handled scrub brush if cleaning a terrace.
Allow to sit for several minutes, 5-10 minutes.
Rinse well with clean water. A push broom works well to remove water.
*Do not mix ammonia with chlorine bleach as harmful fumes result.
PRUNE SPRING FLOWERING SHRUBS…. Now is the perfect time to prune spring flowering shrubs such as Azalea, Fothergilla, Pieris, Rhododendron, Spiraea and Viburnum. After the flowers have dropped off, you can safely prune, and the plant will have plenty of time for the buds to set for next year.
PERENNIALS THAT FLOP….Some perennials become so tall that they become top heavy, and have a tendency to flop, especially after a good rain. Many of us resort to bamboo stakes and ties to keep them upright, but for some plants, there is an easier solution. In June, cut the plant height in half before it starts to flower. This encourages additional branching and a shorter ultimate height which in turn prevents the ‘flop.’ The plant may bloom a little later than normal, but it will still bloom and be lovely. Some of the ideal plants for cutting back include: Aconitum, Aster, Amsonia, Baptisia australis, Boltonia, Coreopsis tripteris, Eupatorium (Joe Pye Weed), Phlox maculata or Phlox paniculata, Platycodon grandiflorus, Sedum ‘Autumn Joy’, and Helianthus salicifolius. Pinching is another good option, especially for Sedum. Snap off the top 1/3 to 1/2 of each stem by hand (they do snap off if you do this with a quick motion). It actually does not take that long to do, and the outcome is much better than if you simply shear the plant. If your flopping plant does not appear on this list, contact me. I’ll be happy to look up the specifics of your plant.
PERENNIALS THAT REBLOOM…AFTER DEAD HEADING…You will be able to coax an additional bloom from many of your perennials if you dead head them immediately after blooming. This works extremely well with Echinacea / Coneflower, Leucanthemum / Shasta Daisy, Salvia, and Veronica.
PERENNIALS AND HERBACEOUS SHRUBS THAT BENEFIT FROM SHEARING…Some Perennials and Herbaceous Shrubs can be pruned after flowering, and will appear to be shrubs all season. Most notably are Amsonia hubrichtii / Threadleaf Bluestar, Baptisia australis / False Indigo, Nepeta sp./Catmint, and Paeonia lactifolia (the Peonies that start fresh from the ground every year). For the Amsonia and Baptisia, I simply shear these below the spent flowers, creating a nice soft mound. The Peonies should be selectively pruned back to foliage you like. With this plant, be on the lookout for Powdery Mildew. When that appears, cut the plant back to the undamaged foliage. At the end of the summer when the Powdery Mildew appears on my plants, I simply cut the whole plant down to the ground.
RENEW UNSIGHTLY FOLIAGE…Foliage can discolor during the growing season either from too much sun (Sun Scorch) or too much humidity (Powdery Mildew). There are other afflictions as well, but the key is whether the appearance of the foliage bothers you. If so, cut down the plant to the height of fresh new foliage, or to 2-3 inches in height if all of the foliage is damaged. Usually, the plant will generate new, healthy, disease free foliage that season. In the rare case that foliage does not reappear, don’t panic. There is a very good chance that the plant will still appear again next year.
