Hello again, Westside Gardeners! As a certified master arborist, I would like to discuss our local shade trees within our city parks and street trees and how to invigorate them into a healthy stage.
As we all know, our native soil type is unfavorable and undesirable for the ecosystem. We need to create a root invigoration program. Our Department of Parks and Recreation or a professional arborist service can muster this program.
Included is the program I developed while working for the Pebble Beach Company. I was responsible for landscaping in and around the Inn at Spanish Bay and Del Monte Forest areas.
My program consisted of a root invigoration treatment, a regimen intended to create a favorable soil environment for root growth and tree performance.
The program has been successful on young trees, recent transplants, maturing trees and even declining trees. Increased root function leads to higher levels of water and nutrient uptake, resulting in an overall improvement in tree health.
Several steps are involved in setting up and implementing my root invigoration program. Site evaluation, tree evaluation and soil sampling are considered first.
The landscape and trees are examined to ensure they are suitable candidates for the service. Not all trees will respond to the treatment, and you should be especially mindful of this possibility when considering declining trees.
Soil analysis options provide information on current nutrient, pH and organic matter levels, as well as soil penetrability and density. My program is simple and effective.
On the day of treatment, the crew will need an air compressor and materials to incorporate into the soil. The soil around the tree well will be cultivated to a depth of 6 to 8 inches using an air spade to till the soil while minimizing disturbance to the roots.
Following the operation, appropriate amendments—such as organic matter, biochar, organic fertilizer and mycorrhizal fungi—will be incorporated into the treatment zone.
The root collar must be excavated so that buttress roots are visible as part of the program. Irrigation should be applied after the soil conditioning to settle the soil and ensure proper contact with fine hair roots.
The final step of the program is to mulch the tree well. I like using arbor mulch. This mulch type is basically group chip tree waste.
It’s essential to maintain the mulch level at 2 to 4 inches. I highly recommend not to plant turf in and around the tree well. Turf will inhibit tree root development and make the program treatment much less beneficial.
Mark Koehler of Los Banos is an arborist and master gardener who has degrees in landscape architecture and landscape horticulture from UC Berkeley and Northeastern University. Please send any questions or comments to markgardenguru@gmail.com.
