Trees and Drought in the Home Landscape
In a perfect world, weekly rain showers during the growing season bring precious water to thirsty Tree roots. Life-giving water allows Trees to grow and expand, to shade us, to shelter wildlife, and to perform their daily functions—not the least of which is the feat of photosynthesis, whereby air and water are miraculously turned into food. Unfortunately, we don’t live in a perfect world, and prolonged droughts sometimes occur. Drought not only interrupts Trees’ daily functioning, but it can cause serious, lasting damage to Trees.
Climatologists tell us that we can expect droughts to happen more frequently in the future. With that likelihood in mind, we are wise to understand how drought affects Trees, to learn what we can do to help Trees cope with drought, and to know which Trees are naturally tolerant of extended dry spells, so that we can keep our Trees healthy and continue to reap their benefits for years to come.
Early warning signs
Contrary to what many people think, most Trees’ roots do not run deep underground in search of water. The majority of Tree roots are found in the top 2 feet of soil, spreading shallowly and widely over time. If the top layer of soil becomes dusty-dry during a drought, a Tree’s delicate feeder roots near the surface begin to die, and the Tree will show early signs of drought stress. These early indicators include:
- foliage losing its luster, turning yellow, or changing into its fall color much earlier than normal.
- leaves wilting, or in severe cases, defoliating early.
- foliage becoming “scorched,” or brown around the edges. Entire leaves may become curled, brown, and crispy.
- buds failing to form properly. For example, Crape Myrtles often won’t bloom in an extremely dry summer without supplemental water, because they’re unable to set flower buds.
Delayed effects of drought
Other signs of distress may not show up until a year or two after a drought event. Trees that have undergone a severe drought should be carefully monitored in the months following a drought. They may be subject to:
- dieback in the canopy. Branches may fail to leaf out in the spring.
- instability. Weakened branches may break in the first strong winds, and Trees with compromised root systems may even topple in a bad storm.
- suckering. Drought-damaged Trees that are prone to suckering will be prompted to send up a plethora of shoots from below ground.
- watersprouts. Some Trees will respond to drought damage by producing a profusion of “watersprouts”—long, relatively weak branches that shoot straight up from the canopy.
- stunting. Growth may be weak when it resumes, and new leaves may never expand to their full, normal size.
- excessive seed production. Stressed Trees often produce an abundance of seed in an effort to keep the species alive as the individual faces possible death.
- disease and insect attack. Drought-stressed Trees are especially vulnerable to attacks from pests like borers and bark beetles and diseases such as root rot and Verticillium wilt.
What you can do to protect Trees from drought
Trees in your landscape aren’t completely at the mercy of the weather. In fact, there are several things you can do to help keep Trees strong and healthy in the event of a bad drought. A little foresight can save a lot of heartache in the future. To protect your Trees against drought, you’ll want to be sure to:
- water newly planted Trees correctly. Irrigate using the Bower & Branch Elements™ Watering System. This system was specifically designed for newly planted Trees and their health and removes the burden and worry associated with watering. Simply refill the container every 10 to 14 days when empty. This system also helps to avoid overwatering, which can cause serious problems, too. Overwatering often has similar symptoms to drought stress (yellowing leaves, wilting).
- keep the surrounding area weeded. It’s also a good idea to remove as much sod around the Trees as possible. Lawn roots compete with Tree roots, and in a drought situation, competition is especially fierce.
- mulch with about 4 inches of shredded bark or wood chips. Check it once in a while to make sure the mulch isn’t so compacted that water isn’t getting through.
- choose drought-resistant Trees in the first place. Trees vary widely in their ability to endure drought. Choosing the toughest ones will make your job of keeping them happy much easier.
Drought-tolerant Trees for the landscape
There are drought-tolerant Trees of all shapes and sizes to beautify your home landscape in all kinds of weather and climates. Many of these Trees can survive on only the rain that falls from the sky once established. Keep in mind that until they are firmly established in the ground, however, newly planted Trees will be vulnerable to desiccation and will need regular water. Here are some of our favorite drought tolerant Trees:
Black Gum, Sassafras, and Common Persimmon are three fine southeastern natives that are naturally adapted to the eastern climate as well as the droughts that occur there from time to time.
The striking Blue Ice Cypress is a fast-growing evergreen Tree. As this species is originally from Arizona, it’s no surprise that it’s also extremely drought tolerant. Other low-water evergreens include Junipers of all kinds, Blue Atlas Cedar, Blue Spruce, and Norway Spruce.
The Chaparral Weeping Mulberry will give you a specimen Tree in a hurry, and it grows in just about any sunny spot.
Bulletproof Ginkgo is a grand legacy Tree to plant for posterity, and it’s a cinch to maintain.
The Golden Rain Tree will delight you with sunny yellow blossoms in the summer when other Trees are simply green, and it is surprisingly drought tolerant.
Sturdy Honeylocust will thrive in the most inhospitable situations. In fall, its tiny leaflets turn gold and then blow away—no raking required.
If you’re looking for a drought-tolerant Maple Tree, the best choices are Autumn Blaze® Maple, Crimson King Norway Maple, and Amur Maple.
Don’t let the Mimosa Tree’s lacy foliage and fluffy pink flowers fool you—this is one tough cookie!
Rugged Oak Trees, like the Pin Oak, Northern Red Oak, and White Oak are the ultimate in toughness when it comes to shade Trees. Regal Prince® Oak and Kindred Spirit® Oak offer slimmer silhouettes.
Smoke Trees bring some sizzle to your landscape and ask for little in return, including water.
Zelkovas are tough enough to use as street Trees. Other good drought-tolerant, urban Trees include Allée® Elm and Bloodgood London Planetree.