(This article is recycled from several years ago, so some of its information is irrelevant to current conditions. Also, it posted more than half a day late.)
After the coolest July in a century, and one of the mildest summers in memory, the recent warm weather at the end of August seemed unseasonable, even though it is actually not unusual for this time of year. Predictions of an Indian summer for this year were made shortly after predictions for this past El Nino winter materialized. The ash blasted into the atmosphere by a volcano in Iceland may have changed all that. No one really knows. The weather continues to change like the weather.
For right now though, the damage caused by the sudden warmth is becoming evident. Fortunately, most of the damage is harmless and should be gone by winter. Some is a bit unsightly. The desiccation of small or potted plants may unfortunately be as serious as it looks. The most severely damaged plants may not recover.
The yellowing inner foliage that eventually turns reddish brown in redwood trees is actually a normal response to foliar desiccation that results from warm or dry weather. As long as the outer foliage remains healthy, this discoloration is harmless. Inner foliage that is more expendable is merely being shed to conserve moisture for the more important outer foliage. This shedding foliage will deteriorate and get cleaned out by wind and rain in autumn.
This older foliage typically sheds naturally throughout summer. However, because the summer was so mild, much of the foliage that should have been shed was not shed. As the weather only recently but suddenly became warm, all the foliage that should have been shed earlier became discolored and began to shed at the same time, which is why it is now so much more noticeable.
A few other trees are also shedding some of their foliage. Trees in areas that are not landscaped or watered may drop dried leaves in even slight breezes. Leaves of deciduous trees that would be colorful and pliable if they fell on schedule in autumn are instead crispy and brown. Maple, oak, ash, sycamore (including plane), willow, poplar, eucalyptus and madrone are among the most affected. Fortunately, this is a harmless response to the warm weather after such a mild summer.
Some Japanese maples are damaged more significantly, but should recover. Because they are naturally understory trees (which prefer to grow in the partial shade and ambient humidity of larger trees), they are not well adapted to warm and dry weather, particularly if it becomes warm as suddenly as it recently did. Some got roasted so quickly that the foliage stays attached to the stems as it shrivels and dries. Foliage that is still partially viable (and hopefully functional) should fall in autumn and winter. Foliage that is necrotic (dead) may linger until it is forced to fall by new foliage that emerges next spring.
Potted plants that were desiccated by the heat may not be so fortunate. Even though they can be unsightly, roasted plants that may be rooted into the ground through their drainage holes should not be moved right away, since the roots that are in the ground are the least damaged and the best hope for recovery. Similarly, roasted plants that hang over the edges of their pots should not be pruned back too severely until later, since exposing the pots to more sunlight will cause more heat to be absorbed if the weather gets warm again.
Does the heat seem to have come on suddenly this year? There was all that rain through winter, then a quick but delightful spring, and now it is suddenly over a hundred degrees in some places! What happened?! There is certainly nothing abnormal about such warmth in the middle of June. It just comes as a surprise when it arrives so suddenly after such pleasantly mild spring weather.
2. Russian sage, Perovskia atriplicifolia, That sounds like ‘piroshki’. These and the rockrose #4 were 5 gallon plants, so are somewhat bigger than most other plants in the new landscape. They were not bothered by the change of the weather. Their faded denim blue flowers continue to bloom nicely. This is a plant that has been popular for a while, but that I have never grown. I tend to avoid trendy plants. However, my colleagues do not.
3. gaura, Gaura lindheimeri, The common name is ‘white gaura’, but some are pink and some are darker pink that is almost red. I do not know if they are merely cultivars of ‘white’ gaura, or different specie. It seemed appropriate to omit ‘white’ from the name. Besides, that is how I learned it. This one can self sow enough to be an annoyance. Individual plants do not live very long, so a few feral seedlings can be selected to replace them.
4. rockrose, Cistus cretisus, When I learned about rockrose back in the 1980s, we learned only two specie. One was white rockrose. The other was pink rockrose; and the pink rockrose did not look like this one. Now, there are too many to remember. Most do not have species name, but merely cultivar names. I really do not know if this really is Cistus cretisus. It just happens to look like it. I suppose I should have looked at the label.
5. chocolate coreopsis, Coreopsis ‘Chocolate’, As I implied for #4, nomenclature is not what it used to be. It was standardized to simplify things, but is difficult to keep track of now with all the breeding and hybridizing, and botanists wanting to make a name for themselves by changing a name to something supposedly more accurate. I really do not know the species name of the chocolate coreopsis. It is known merely by the cultivar name.
6. milkweed, Asclepias tuberosa, This one wilted rather badly in the warmth, but did not get roasted too much. The shriveled flowers in this picture are the worst of the damage. It is blooming more profusely now, and is developing strange seed pods. Milkweed is another trendy plant that caters to the butterfly gardening fad. I am not certain if I like the idea of planting something that is expected to get munched. It sure is colorful for now.
This is the link for Six on Saturday, for anyone else who would like to participate:
This really is the best climate here. Winters are just cool enough for many plants that require a bit of a chill, but not unpleasantly cold. Summers are just warm enough for most plants that need warmth, but the weather does not stay too unpleasantly hot for too long. Warm weather here typically lasts no more than a week, and is accompanied by light evening breezes and cooler nights. Minimal humidity typically makes the worst of the heat a bit more tolerable.
This does not seem like such a mild climate when it is difficult to distinguish between the time and the temperature on a local bank clock tower. You know; when punctuation is the only difference between four minutes past one, and one hundred four degrees. Fortunately, like mild frost in winter, hot weather does not happen too often, which is why this climate really is milder than most.
One of the most important differences between plants and animals is that animals are ‘animated’, and plants are not. Aquatic plants might float about, and might even drift into more favorable situations. Vines and plants with creeping rhizomes can likewise relocate. Otherwise, most plants are confined to the same locations where they grew naturally, or where they were planted. They need to get it right from the beginning.
Tony Tomeo 