I’m not sure if you have noticed, but it’s been a hot summer. (As a horticulturist, I am always planting; just now I planted my tongue firmly in my cheek.) Last year, July was cooler and wetter than normal, this year just the opposite. Long hot spells with few breaks in temperatures, and the occasional severe thunderstorm to keep it interesting.
Right now, I am typing on battery power on my laptop, with candles for illumination. I feel like Young Abraham Lincoln, practicing arithmetic by the fireplace, using chalk to write on the back of my shovel. [Note to self after power restored days later: in future, save battery for other endeavors.] I’d like to encourage you to water your plants from time to time. Remember: unlike you with your pint bottle of water on your desk, your plants can’t walk over to the water cooler for a refill. Just as you wouldn’t leave a dog in a hot car, our plants depend upon us to help us through hot summer weather.
The street trees in town are often forgotten. These are the unlucky trees planted in what is called the “Hell Strip,” the area between sidewalk and curb. Called that because it gets hotter and drier faster than other areas due to the heat radiating from street and sidewalk. Also, since the soil area is small, there isn’t a lot of room for water to soak in when it does rain. It’s also often salty, from road salt and pet urine. (Salty soil is a problem for plant roots, they don’t work as well as they do in “normal” soil. It’s the reason that you shouldn’t fertilize a plant in stress; it may make things worse.)
People tend to think of those street trees as the city’s responsibility; as a result, street trees tend to be short-lived. Give them a break and run the hose on the soil out there for awhile, or at least take out a couple of watering cans. Plants vary in their ability to survive periods of drought. Needle-bearing evergreens, such as pines and junipers, tend to be drought tolerant once established (that is; in the ground for a couple of years). Newly-planted plants need to be checked frequently in hot weather because they have a limited root system, initially confined just to the potting soil that they came with. Remember to soak them well, then let them dry out for a couple of days to encourage the roots to grow out into the surrounding soil in search of water.
Especially in the western US, Xeriscaping is becoming the norm; that is, landscaping with plants that tolerate or even thrive in dry conditions. (A Xeric environment is a dry environment. Xeriscaping means landscaping with drought tolerant plants.) Areas with large populations and little water are realizing that they don’t have the resources to maintain lush lawns and temperate plants. Depending on the locale, people are switching from lawns to desert plants, or Mediterranean climate plants. The latter do well in dry and often hot summers, and cool winters when they get the bulk of their limited rainfall. These also tend to be areas with poor, well-drained, rocky soils. Lavender and rosemary are Mediterranean climate plants.
What about Xeriscaping in our area? We have a problem with poor-draining clay soils, wet winters and summers that are often wet and usually humid. Mediterranean plants such as lavender often die here during the winter from root or crown rot, and in the summer, they are prone to foliar diseases from the high humidity. You can help combat these problems by planting where there is good air circulation, and in soil that drains well. This may mean on a slope or in a raised bed. Mulching these plants with gravel instead of bark helps too; it keeps the stems drier and reduces rot. That said, there are lots of plants that don’t require a lot of supplemental water in the summer, and can be used to replace areas of lawn.
By Larry Hurley, Perennial Plant Buyer