As our Mediterranean climate launches into dry summer with temperatures soaring to full throttle, garden plants also feel the heat. Indications of heat stress in landscape and garden plants include, wilting or drooping leaves that do not return to normal by evening; curled or chlorotic (yellow) leaves that may fold or drop; new leaves that are smaller than normal; or foliage that becomes grayish and loses its green luster.
For areas under water restrictions, as some of us are right now, prioritizing which plants receive valuable water is a consideration. Many homeowners choose to use available water for mature landscape ornamentals and fruit trees. One or two deep irrigations, several weeks apart during the hot months will often help these valuable plants survive. Trees can often survive one season of drought, but subsequent seasons of drought can result in severe stress and even death. Drought stressed trees are more prone to damage from disease and insects.
In order to produce a good crop, fruit and nut trees need adequate water in the root zones from bloom to harvest. However, the trees can survive drought conditions with some early applications of water, although fruit production will be decreased. For vegetables, timing and amount of water are critical to obtaining an adequate harvest. Water is most critical during the first few weeks of development — after transplanting into the ground, and during flower/fruit production. Typically, tomatoes, beans and root crops require regular watering and generally don’t tolerate long dry periods.
Newly planted trees, shrubs and ornamentals can take a while to adapt to new locations and may need extra watering as roots grow – water when the top 3 to 4 inches of soil is dry. Water until the soil is moist to a depth of 8 to 10 inches, which can be checked by inserting a long screw driver or piece of rebar into the soil to about 12 inches. If moist soil is found on the device, water is seeping deep enough to feed roots.
The watering schedule for established trees will depend on the age of the tree. In general, a mature tree will benefit from a low-flow system (such as drip irrigation system with emitters) for 12 to 24 hours every 21 to 30 days, depending on the weather and species of tree. Water just inside the drip line of the tree (the area of the leafy canopy) to about 5 feet beyond the widest limbs where most of the feeder roots grow. Never let water settle near the trunk of a tree.
Adding mulch is a boon to home gardens. Mulching is simply the process of covering the soil around plants with organic (straw, wood chips or bark for example) or synthetic material. Mulching helps protect roots from high temperatures, helps reduce loss of soil moisture and suppresses weed growth. Weeds compete with garden plants and trees for water. One essential rule to using mulch is to pull mulch material away about 3-inches from the base of the tree or stem of the plant.
To learn more, the Master Gardeners of Nevada County will present a workshop, Gardening in Drought on Saturday, July 30, from 10 a.m. to noon. The workshop will be presented at the Demonstration Garden on the NID Business grounds, 1036 West Main St. in Grass Valley.
Another tip for hot summer gardens is to observe the garden for pests — whether chewing the leaves or taking down entire plants, managing pests stems on figuring out what the culprit is. Integrated Pest Management (IPM) involves identifying the suspects, determining the degree of interference with desirable plants, and how to manage the pest. To help identify pests, observe what is happening with the plants in a given area. Are there visible insects chewing on leaves, or is there goo arising out of the bark of a tree? Observations will help target research as to what the pest is. Take a flashlight and look at night to see what lurks in the darkness! Online resources for pest management can be found on the UC Davis IPM website at: http://ipm.ucanr.edu/. This is an excellent source for treatment protocols as well.
Another garden task for summer is to deadhead annual and perennial plants. Deadheading is simply the practice of cutting dry or dead blooms off plants. Removing the flower (not just the dry petals) will also remove the seeds which is really what we want to accomplish by deadheading. Many flowers will bloom again after spent blossoms are removed. Deadheading may also promote more attractive growth habits, and prevent reseeding where you don’t want reseeding to take place. By cutting just above the first leaf, most plants can be deadheaded without affecting the rest of the plant. For those who find deadheading more tedious than relaxing time in the garden, there are varieties of flowering plants that don’t need to be deadheaded – just check with our local nurseries. And, please consider planting perennials later – in the fall as the cooler temperatures and rains set in. Planting now will require more water to get the plants established.
For more information about Master Gardener workshops, events and other great gardening links, go to our website at http://www.ncmg.ucanr.org.
Ann Wright is a Nevada County Master Gardener.
As our Mediterranean climate launches into dry summer with temperatures soaring to full throttle, garden plants also feel the heat. Indications of heat stress in landscape and garden plants include, wilting or drooping leaves that…
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