Tree Health Assessment

Knowing a few things about the proper planting of trees is the first critical step toward ensuring good health for the entire life of your tree. Most trees purchased from nurseries are delivered in a pot, but occasionally you’ll come across young trees that are delivered bare-root or wrapped in burlap. These instructions are for planting a containerized tree, but either way, you can adjust based on these basic tips. First, the hole. Most importantly, the hole should not be deeper than the container. The root flare at the base of the trunk should be slightly above ground level. If you find that your hold is too deep, add some soil to the bottom and compact it down to adjust the depth of the hole according to the container depth (or that of the roots). A tree that has been planted too deeply will struggle and eventually die, as the actual trunk of the tree is not meant to be surrounded by soil. The hole should be 3 to 4 times wider than the container, and have sloping sides like a saucer. Once the hole has been dug, take special care in removing the tree from the container before placing it into the hole. Try to keep the soil around the roots intact. This will be hard if it is too wet or too dry. Tap the outside of the container to gently loosen it. If a tree has spent a long time in a small container, it may have become root-bound, meaning the roots have grown in a circular pattern. If a tree remains root-bound after being planted in the ground, it will fall over sooner or later. The most secure trees have major roots that follow a radial pattern of growth outward from the trunk — looking like the spokes of a bicycle tire, roughly one foot under the ground — with tinier roots attached to this that do most of the absorption. So, aside from the job of transporting water and nutrients from the soil to the rest of the tree, the roots act to firmly anchor the tree, supporting its size and weight, as well as its movements as it bends under the pressure of wind or other forces. So, if your containerized tree seems to be root-bound, fetch a sharp knife. Cut an “X” across the bottom of the root ball, as well as four vertical slices. This should help break the circular pattern established in the pot and hopefully encourage normal outward root growth after planting. Once placing the tree into the hole and ensuring it is not too deep, pack some soil around the root ball to help keep the tree upright. Then continue to backfill the original soil, avoiding air pockets, until the hole is filled and almost level with the root flare at the base of the trunk. When backfilling, you can shape a sort of basin to hold water close to the root ball, or form a berm all around the circumference of where the hole was. Water the area slowly and thoroughly. Except right against the trunk, put down a protective layer of mulch, a few inches deep and about as wide around as the hole was. Don’t forget to remove any tags or labels from the tree, or these may be enveloped by the tree as it grows.

Newly planted trees — A newly planted tree will need more frequent watering for at least the first several months. Just after being moved from the container to the ground, the roots will all be concentrated in the original root ball area (the size of the container it once occupied). Water this area well, plus a bit beyond it. Some watering may be needed almost weekly for the first year. The aim is to keep the soil moist, but not soggy.
•    Desert varieties — This includes (but is not limited to) the mesquite, palo verde and palo brea, ironwood, acacia, and desert willow. These desert trees, being native to the Sonoran Desert and having developed special adaptations for the area, typically need no more watering than what nature provides. In the case of drought, one or two deep waterings during the driest part of the year wouldn’t hurt. However, these desert trees often receive more watering than from rainfall alone, simply because their roots likely extend into neighboring yards where other shrubs are watered on a regular basis. The overwatering of desert trees can pose a problem, because it will encourage rapid brushy growth, which leads to poor structure and a dense canopy that is more vulnerable to storm damage.
•    Established (non-desert) trees — It may take a couple years after planting for a tree to become established (or longer if it was a larger container stock tree at time of planting). Infrequent but deep watering is better than shallow, frequent watering. It is best that the soil experiences some dryness before being watered again, because most trees do not tolerate well conditions where the soil is always wet. This is because water displaces air in the soil, which can suffocate growing roots. If you dig around a bit and the soil feels soggy, it’s not a good time to water again yet. The ideal watering schedule roughly imitates flood irrigation: deep watering once per month during the cooler part of the year; twice per month during the hotter part of the year. The actual amount of water used may depend on the soil conditions: soils with a lot of clay hold more water; soils with more sand content hold much less and thus will need more watering to maintain the health of the trees. These factors in soil quality will determine how best to irrigate the soil. Whether you use a drip system, sprinklers, or a plain old garden hose to irrigate, initially you will need to pay attention to how readily the water is absorbed in order to avoid flooding and runoff. This is trickier in badly compacted soils, which may require repeated cycles of turning the hose on and off if there is a lot of pooling and runoff. Clay-rich soils also absorb water at a slower rate, so the hose will need to be turned low, perhaps just a slow trickle, and left on longer. The goal is to wet the soil in the root zone to a depth of 18-24 inches. Remember, too, that the roots of a tree radially extend well beyond the area of its above-ground canopy (three times that, give or take). After a while you will establish a nice watering routine suitable to your schedule and your trees’ needs. Until then, it may help to designate dates on a calendar or use some other method for reminding yourself, as well as some sort of timer, so that the running of water is not forgotten. Obviously, if heavy rainfall has been received, you might get away with postponing one watering. Certain tree varieties are “thirstier” than others. If you know which types of trees you have in your yard and do a bit of research, you might adjust your watering habits accordingly. Also, efforts to improve the quality of your soil (such as mulching) will make your watering easier and more efficient.  

Benefits to mulching — Mulch retains water to keep the soil moist after watering, insulates the soil from extreme heat or cold, prevents compaction of the soil, and minimizes root competition by keeping weeds out (especially with deeper layers of mulch). As the mulch decays, it will enrich the soil. After some time passes, you will be amazed to see how lovely, dark, aerated and earthworm-filled your soil becomes where it was mulched!
•    How to apply mulch — Spread or pour the mulch pieces around the tree within a 3 to 10 foot area, depending on the tree’s size. You may wish to remove grass within this radius prior to laying down the mulch, but this is optional. Keep the mulch from touching the trunk of the tree itself. You may want to add more periodically.
•    Wondering where to obtain mulch? — From us, of course! Many types of organic matter works, but wood chips make especially good mulch, and we nearly always have a ready supply of it. If you just let us know that you would like wood chips, we will be sure to show up soon with a clean load of it whenever we are in your area. Let us know where to dump it, and you provide the labor for spreading it wherever it is most needed on your property. If you don’t want a huge amount, it isn’t quite as easy. If we are out at your property for tree trimming or removal, we will be chipping up the brush and hauling the valuable woodchip mulch away. However, if you would like, we can chip directly onto your lawn. You may then rake the chips evenly around or concentrate them around trees or shrubs to take most advantage of the wonderful mulch we leave for you.Please do not attempt a tricky tree removal yourself unless you’ve had appropriate training; leave the tough jobs to the experts! We offer free estimates; you may be pleasantly surprised by the price.

Adding fertilizer regularly to your trees may not be necessary. However, if a deficiency is indicated, adding fertilizer can increase their resistance to disease and insect damage. A Certified Arborist can help you determine whether your tree needs extra fertilization by examining the condition of the foliage. Newly planted trees and trees whose root systems have recently undergone trauma should NOT have fertilizer applied until given time for their root systems to recover (from the planting or from such things as construction work or trenching). The best times to fertilize trees or shrubs are either late spring or late fall/winter (once they become dormant). Some fertilizers, especially those formulated for use on lawns, contain herbicides, and should not be used for trees! A mature tree’s root system, through which the tree absorbs the nutrients from soils (including any fertilizers added to it) extend well beyond the size of its canopy. Thus, fertilizer can be applied to the soil under a tree in an area that is at least 1.5 times the spread of the tree’s branches. It is recommended that 3 pounds of actual nitrogen be added per 1,000 square foot of this area. On commercial fertilizer, the amount of nitrogen (N) is expressed as a percentage. The rest of the mixture will be a percentage of phosphorus (P) as phosphoric acid, and potassium (K) as potash. Common proportions found are 20-5-5 or 12-12-12. So, a 50 pound bag of 20-5-5 fertilizer contains 20% nitrogen or 10 pounds of actual nitrogen. If you know the size of your treatment area in square feet, you can determine how many pounds of fertilizer to purchase based on the amount of actual nitrogen in the mix. The granular fertilizer blend will remain atop the soil (or grass, gravel or mulch layer) until the tree is watered, at which point the added nutrients will be able to mix into the soil and be absorbed by the tree’s roots. If you are unsure about any of this, and if you frequent a nursery where you trust the people there to be knowledgeable about their products and how to use them, it doesn’t hurt to ask a them for additional instruction.