As mentioned, the trees that are most vulnerable to drought are those that are newly planted. Most people have grown accustomed to buying fairly large (~6-8 foot in height) trees at local garden centers. These trees are grown in pots, and usually have very thick secondary root systems, frequently circling the interior of the pot.
Even if planted using the best techniques (discussed below ), these roots will mostly grow laterally, staying near the surface. This lateral growth allows them to absorb rain right after it falls, but also makes the roots very susceptible to drying out in periods of drought. When rain is infrequent, the area closest to the top of the soil dries out first. If all or almost all of the tree's roots lie in this top soil zone, then the tree can quickly dry out and die (or become more susceptible to other diseases like pests). For this reason, it has long been advised that you water trees deeply yet infrequently, in an attempt to get these roots to grow more deeply.
In practice, store bought trees with such thick root balls can rarely have their roots redirected downward. When you have a new, store bought tree, the best you can do is dig an appropriate hole (twice the width and one times the depth of the root ball) and make sure the tree stays watered when there is no rain. An alternative is to use a watering bag like the TreeGator®, but these bags also need to be refilled by a human, not saving much effort but greatly increasing cost.
Buying trees from garden centers often leads to disappointing results. According to Richard Harris, Professor of Environmental Horticulture at UC-Davis, "the smaller the plant when transplanted into the landscape, the better will be its relationship to the environment" (Kourik, 2008). For this reason we recommend the method of planting detailed below.
A new and better way to grow trees that will be permanently drought resistant is to grow younger trees (saplings) that still have their primary (tap) root, and to grow these trees with the Groasis Waterboxx. The Waterboxx is a deceptively simple invention. It functions in multiple ways to ensure that tree roots grow downward, not laterally near the surface. It does this by collecting dew and rain water and slowly channeling it to the taproot of the tree. The slowly released water forms a column beneath the Waterboxx, and the trees roots will grow straight down within this water column. "When it comes to moisture, roots are lazy. They won't grow to a water source, but will grow where there is moisture." (Kourik, 2008). After this root growth, the Waterboxx can then be removed, leaving behind a tree with a deep taproot that has much better access to deep moisture in the soil.
As you can see in the video above from Groasis, the Waterboxx will make trees resistant to drought long term, thus allowing the landowner to conserve water. If you are interested in purchasing the Waterboxx, please visit our parent website, Dew Harvest. We would love to hear your comments below - to leave one, please click on "Comments".
Kourik, R. (2008). Roots demystified: change your gardening habits to help roots thrive. Occidental California: Metamorphic Press.