Have you noticed the Dogwoods, especially the Cornus florida / Native Dogwood and Cornus kousa / Kousa Dogwood? They put on quite a show this year. Unfortunately, the late freeze we had in April damaged much of the young foliage on a number of shrubs. In my garden, Hydrangea macrophylla / Bigleaf Hydrangea, Schizophragma hydrangiodes / Climbing False Hydrangea and several new arrivals fresh from southern nurseries were the hardest hit. All are starting to push out new growth, and before long the damaged foliage will drop or be hidden by the new. These plants could benefit from a little extra fertilization as they attempt to leaf out for a second time.
As far as our plants are concerned, we went straight from April to August. The cool, rainy days in May were a gift to our plants, but the high temperatures we are experiencing now are quite stressful for them. Do give them water when you can.
WHEN TO WATER…The temperatures have already started to soar, 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.
HYDRANGEAS… I love Hydrangeas for their bold, bright blooms that seem to last forever. Unfortunately, my Hydrangeas have been hard hit by a late freeze for the third or fourth year in a row. The ‘Endless Summer’ cultivars that bloom on first and second year wood perform better than the more traditional cultivars that only bloom on second year wood, but I am still so disappointed. We should all be supplementing our Hydrangeas with Hydrangea paniculata varieties. The blooms are big and bold, long lasting, and the plants hold up well to late spring freezes. New cultivars are appearing every year. Many of the better known cultivars are quite tall, 6-8’ HT such as ‘Tardiva’ and ‘Limelight’. ‘Vanilla Strawberry’ has pink and white on the same panicle. ‘Little Lime’ and ‘Silver Dollar’ are dwarf forms that should not exceed 3’ HT. I recently stumbled across ‘Magical Flame’, a dwarf form with Bubblegum Pink panicles that turn Deep Pink – Red as they age. H. paniculata starts blooming later than H. macrophylla. In most cases this means August – October which is a substantial show.
BRINGING PEONIES INSIDE…Many Peonies have started blooming, treating us to their delicate beauty and welcome fragrance. The flower heads are so heavy that many flop after only a day, especially when it rains. You can outsmart Mother Nature by bringing them inside. When the buds are full and the ants have finished eating the outer coating, cut the buds, dunk in cold water to remove any stray ants, and refrigerate until ready for use. If you arrange the buds in the morning, they will usually be open by dinner.
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, 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.