The relationship between trees and lawns can range from harmonious to horrendous. As the gardener, you’re the shepherd who decides the fate.
In a quality landscape, lawns and trees need each other like stars need the night and a sailboat needs a breeze.
The key to lawn and tree harmony lies buried in the dirt. Those (hopefully) deep and hidden roots tell a revealing but secret tale of the tree’s health. Taking proper care of the roots can make the tree’s life journey easier, safer, better and longer.
One goal is to get the lawn roots to grow deep (two to six inches) and the tree roots to grow way deeper. In most lawns in our area, grass and tree compete greedily for water, air, and nutrients scarcely below the soil surface.
The formula for avoiding shallow roots is an easy one: aerate at least annually, water deeply and infrequently and fertilize through spring and fall only.
Most folks can’t recall the last time their lawn was aerated, but have recently poisoned the soil with usually unnecessary things like pre-emergents, pesticides, fungicides and/or herbicides. Good soil is alive, poison free, and encourages roots to grow deeper. A thorough soil aeration results in root rebirth.
The most important way to water grass with lawn trees is to provide the lawn with water only as it begins to show the first signs of drought stress, then commit to a deep and long watering for the tree’s sake. If a timer is exclusively programmed to conveniently water the grass every day, even though it could go longer between watering, the tree roots will follow the surface water. Since tree roots are bigger and more competitive than grass roots, they’ll eventually force the lawn to struggle and be sparse beneath most of its canopy. To further encourage deep tree roots, water the entire tree surface area long and slow, letting three or more inches of water to penetrate several feet into the ground. Do this once a month during the summer.
Overwatered lawns with visible tree roots are a hazard for the trees, since these roots can be easily damaged by lawn chemicals and collisions with machines and other tools. High mowing (cut to 3 inches tall or higher) allows you to go a little longer between lawn waterings.
Trees appreciate in value as they grow while lawns tend to depreciate. Grasses thrive as sun worshipers, and the denser the shade from growing trees, the more sparse they become. Besides the above-mentioned care tips, this situation can be remedied somewhat by proper pruning and growing the right lawn trees. Avoid trees such as birch, poplar, sugar and silver maple (greedy surface roots) and mulberry (crowded, big leaves causing dense shade). Chinese tallow, sycamore and liquidambar are OK only if the formula mentioned above is applied conscientiously, otherwise get set for shallow root syndrome.
The best lawn trees for our area include hackberry, red oak, ginkgo, linden, Chinese pistache and Japanese zelkova, and small trees such as Washington thorn, saucer magnolia and crape myrtle.
For the first two years, don’t prune the new tree. The extra branches will help thicken the new trunk while preventing sunscald to the trunk. From year three to ten or so, entirely remove two or three of the bottom most limbs so it eventually provides lots of room to walk under while allowing more early morning and late afternoon sun to reach the grass. Never top a tree, and consider having an arborist prune your large trees to let in more sunlight.
Fall is best for choosing trees such as Chinese pistache and liquidambar for the autumn colors you like.
Marc Soares lives in Redding. He is a landscape consultant for already existing gardens. He’s also the leader of Indigo Brew, a jazz band which will be playing March 2 at Redding’s Old City Hall. He is the director of the West Valley High School Band, and swim coach for the Anderson Aquagators and West Valley High School.
Soares is author of “100 Hikes In Yosemite National Park,” and “Snowshoe Routes of Northern California – The Mountaineers.” He can be reached at firstname.lastname@example.org.