Planting Guidelines Part III: Post-Planting Care
The most important consideration in post-planting care is watering. The majority of plants which die, die because they are either under-watered or over-watered. There is no way to prepare a generic set of watering instructions which covers every planting situation. This is because there are too many variables to each planting and each set of variables requires a slightly different modification in how to most effectively water for the given planting situation. This variability even extends to different plants within the same property.
Neither our valued customer nor ourselves want a plant to die. Both take pride in growing a beautiful plant and appreciate the long term value they bring into our lives both aesthetically and monetarily. Because of a plant’s critical need for effective watering and the resultant outcome and impact when it does not occur, we have prepared this expanded, supplemental Post-Planting Care Guideline to assist the homeowner in better understanding the issue from an overall standpoint. It is an extension of our regular planting guidelines and presents many of the reasons we recommend planting in the manner we do.
An Overview of Watering
Why is Effective Watering so Difficult?
Rapid establishment and the long term growth of trees and shrubs is dependent upon the root system. Therefore, when planting every advantage must be provided for the growth and regeneration of the roots.
When planting there may be extreme differences in the texture, compaction and organic matter between the soil of the plant, the existing soil and the back fill material. This difference causes an effect called hydrologic discontinuity to occur. Water does not readily penetrate the interface of heterogeneous media until saturation of one medium is reached and surface tension forces are overcome. When there are major differences between the site soil, the back fill and the medium the plant is growing in these extremes often result in the acute stress or sudden death of newly transplanted trees and shrubs. This is a key reason why amending and/or fertilizing the back fill is not recommended. Doing so adds a third adjacent soil to contend with (versus two).
In an attempt to explain, the porosity of a soil determines how easily it will give up its water. A saturated medium will give up moisture the most easily. Sandy soil is the most porous and will take and give up moisture the quickest. Good black soil could be considered medium and will give up and take water at a medium rate. Clay soil is the least porous and takes and gives up water the slowest. When the plant planted has been grown in a coarse (porous) mix the roots have trouble pulling water from the surrounding back fill and/or existing soil. That is why often the surrounding soil seems to be moist and adequate, however the medium around the plant is very dry. Even though moist it is not moist enough to overcome the moisture tension between itself and the medium the plant has been grown in. Looked at another way, the more compact the soil the more surface tension there is (unwillingness to give up moisture) The converse of this can also occur. Newly planted material can succumb to root suffocation caused by poorly drained soil pits.
When looked at in this manner one can easily see the possible permutations which can occur when multiple, dissimilar soils exist within the planting area.
Why Water is Critical To a Plant
Water is the most limited essential resource for plant survival and growth. Water shortages severely damage young and old plants alike. Lack of water can also setup healthy trees for other problems such as tree decline, pest problems and nonrecoverable damage.
Plants need between one inch and three inches of water per week distributed through watering or rain during normal temperatures. The amount will depend upon the soil type.
The small, water-absorbing roots of plants are easily damaged during transplanting. For sufficient water uptake to occur the root ball of a newly planted tree, shrub or evergreen must be kept moist, but not saturated, and it must not dry out.
Key Variables in Establishing Water Needs
For every 18 degrees change in the temperature the amount of water lost by a tree almost doubles. Therefore it is critical to factor temperature into plant watering requirements.
Trees surrounded by pavement or other hot surfaces can be 20 to 30 degrees warmer than trees in protected backyard locations.
Trees constantly lose water to the atmosphere.
The Principles of Effective Watering
Understanding How to Water
The majority of the plants’ absorbing roots are in the top 12 inches of the soil.
Water does not move sideways in a soil, it moves downward. You should top water and apply the water directly over where you need water in the soil. Surface watering allows the greatest chance for a plant to absorb water, helps maintain soil health, and helps essential element cycling and transformations in the soil.
The best way to water trees is by soaker hose or trickle (drip) irrigation.
Less frequent and deeper watering from the surface is more beneficial than light watering. Deep watering by sticking a pipe or wand into the soil 18-24 inches is not as good for trees as surface applications for this reason. Below 24 inches misses the active roots.
One half gallon (.5) of water per square foot equals approximately one gallon of water per square foot. To extrapolate, if the area needing to be watered is approximately one square yard (the area one would want to water if they were to plant a 2 inch balled and burlapped tree), then one would need to slowly apply approximately 15 gallons of water evenly over the surface area every week under normal weather circumstances, with normal soil conditions. The area to be watered calculation allows for watering a small amount of area outside the diameter of the plant hole as the edges of the soil buttressing up against the refilled plant hole should also be watered to encourage root growth in the surrounding soil.
Testing for Drainage
Dig a hole where the plant is to go and fill it with water. Allow the water to stand for 24 hours. If the water has not completely drained from the hole in that period, then special planting and watering procedures may be necessary.
Key Variables Affecting the Amount of Water Needed
Soil texture is a primary determinant as to how much water a plant will need. The size of the root ball plus the size of the planting hole is a primary determinant as to how much water a plant will need. Heavy clay soils severely restrict the movement of water and commonly lead to saturated conditions. In areas with high levels of clay or silt (finely textured soils) newly planted trees should receive no more than 1 inch of surface water per week during the growing season. Supplemental watering is not necessary during periods of adequate rainfall.
Sandy soils drain more easily, therefore up to 3 inches of water per week may be necessary to keep the soil moist. Carefully monitor the moisture level in the root balls of evergreen and trees which are planted in sandy soils. Water does not drain easily from the fine textured soil of the root ball into the surrounding sandy soil. Therefore the root ball may become saturated.
