I planted 3 weeks ago and now I'm seeing some branches starting to wilt and some branches turning brown. What do I need to do?
Multnomah County Oregon
Whenever woody trees and shrubs fail shortly after planting, the problem is usually due to the water supply – either too much or too little. Most people refer to such wilting as “transplant shock” whereas a more accurate explanation is that the roots are receiving too little water to supply the requirements of the top growth.
The first step to successful transplanting is to thoroughly moisten the original rootball by submerging it in water until bubbles stop rising.
The second step is to dig a planting hole the same depth as the original rootball and two or more times as wide. Next, fill the hole with water and allow it to drain completely; then repeat.
The third step is to set the rootball into the hole, then refill around the rootball with the native soil. Don’t add any fertilizer, compost, or drainage material.
The final step is to follow-up by adding supplemental water to avoid wilting. Plan on at least 2 years for the arborvitae to be fully established, when you should water them deeply once a month through our dry seasons.
Begin with watering the area of the original rootball as often as you would as if the arborvitae were still in the pot. Water the surrounding soil less often, with the goal to maintain adequate moisture for root growth to extend outward.
After each watering verify the soil moisture content by sticking a finger into the original rootball. The entire rootball must be kept evenly moist as the roots extend into the surrounding soil.
Also, verify the moisture content of the soil surrounding the rootball. It must be irrigated on a regular basis but less often than the rootball simply because the roots aren't out there as yet.
A regularly scheduled series of irrigations is required to help a newly planted tree to develop a vigorous, sturdy root system which will be able to support the tree’s needs for many years. The goal is to gradually work toward the basic requirement of the arborvitae.
A rather detailed irrigation schedule is recommended for the first 2 years of the tree’s life in its new site. The larger the tree when it was planted, the more years it will need supplemental water to develop its root system.
Because our weather reports warn of an impending heat wave, consider rigging temporary shade and perhaps windbreaks as protection, perhaps retaining it through this summer.
These publications include all the specifics of establishing and maintain woody plants:
(1) “New Tree Planting” - http://www.treesaregood.org/portals/0/docs/treecare/New_TreePlanting.pdf.
(2) “Watering newly planted trees and shrubs” - https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/watering-new-trees-shrubs/.