When a tree fails, it is sometimes difficult to determine the cause. In many cases, it is due to a failure to spread the roots out in the planting hole or simply planting it too deeply, which leads to girdling or lack of an adequate amount of oxygen, resulting in death. Other than the correct planting procedure, lack of good follow-up care is the next most common cause. Each is important in ensuring a successful planting. Just like planting errors, many follow-up procedures can be done improperly or forgotten altogether.
Watering a newly planted tree is not simple. With trees, the soil volume is much larger and often nonhomogenous. Layers of differing soil types often exist, decreasing percolation. Gravity causes water to drain downward from newly planted tree root balls, but in some cases, not as freely or much more freely than desirable.
With this in mind, it can be difficult to know how and when to water. A few guiding principles and techniques can help. First, probe the soil with a sharpened metal rod. If the probe goes in easy and makes a sloshing sound, the soil is too wet; if the probe won’t penetrate easily, it’s probably too dry. Feeling the end of the probe can also give you a hint about how moist the soil is, especially if a little soil sticks to it.
Secondly, most trees need only half to one- third as much water as turf does. Keep this in mind when scheduling irrigation times. Third, separating turf and ornamental plantings is helpful, because each is so different in terms of water needs. A landscape with trees floating in an island of turf is problematic.
Depending on the arrangements of the landscape elements, temporary and permanent irrigation systems can be installed to provide the right amount. A thoroughly watered, but not soggy, planting area is the goal, especially before the onset of winter. After installation of the system, monitor and measure the output to make sure that it is delivering water at the desirable rate.
Staking is an “as-needed” procedure, generally not automatically recommended for tree planting for two reasons. The most obvious is that it takes time and costs money for the materials. Secondly, it is highly desirable for new trees to develop a strong network of lateral roots, which can be limited by staking.
Even though not a good routine step, if the site is a windy exposure, staking may prevent new trees from being blown over in the planting hole. Additionally, if the tree’s root system is going to be limited, such as in a street planting, staking should be considered. In any event, be sure to tie the stake loosely so it can sway 3 inches or so from side to side. Wide bands are preferred over narrow ones, even if buffered by lengths of garden hose. Stakes should be removed after one growing season.
For the overall sense of proper mulching technique, take a cue from Mother Nature. In a forest or natural setting, you’ll commonly see a 2 to 4-inch layer of fallen leaves, stems, fruits and bark, often referred to as “duff.” Over time, the nutrients in the duff materials decompose, recycling nutrients back to the tree. As much as is feasible, replicate this phenomenon for new plantings. Avoid applying massive depths of mulch or mounding it up on the trunk in a volcano appearance.
Various sources of mulch can be utilized, but, in general, natural/organic mulch is best, wood chips, bark chunks, pine needles, cypress, cedar and hardwood. Rock mulches have become popular with some customers because of their color and the minimal need for replacement, but they are much harsher on new trees as they add heat and don’t decompose to recycle nutrients.
Weed mats under the mulch are another common, but unnecessary, material. While allowing water infiltration and oxygen exchange, they usually cause problems with weeds actually growing in the fine pore spaces of the mat, and, as with staking, they require the input of resources. However, on a moderate to severe slope, they can be of some assistance in holding freshly dug soil in place.
Like staking, pruning is an “as needed” procedure, although the need in the first year is not great. In fact, because young trees need every leaf they can get their chloroplasts and vascular bundles on, pruning should be avoided in most cases. If branches are removed at planting time or shortly after, the tree is being deprived of critical carbohydrate and sugar-making ability. Branches that are oddly oriented should be left for removal in year two of the planting.
Some trees are badly misshapen and must be pruned minimally after planting. Defects such as codominant leaders, badly rubbing branches and broken branches fit this category. These problems are severe enough that taking the risk of not being hired to return for corrections in the second growing season is not justified.
If mulched properly and growing on decent soils, the majority of newly planted trees don’t need any supplemental fertilizer. In fact, applying fertilizer soon after planting can be counterproductive, especially if it contains nitrogen, phosphorous and potassium.
Overall, the goal for the first year after planting is to establish a healthy, lateral root system that is able to mine the soil for water and nutrients, as well as anchor the tree. Applied fertilizers generally encourage growth of the leaves and shoots in favor of roots.
If concerns exist about the existing nutrient levels in the soil, taking a soil test can be helpful in determining which elements may be lacking. Information about the pH of the soil, salt content, bulk density and microelements can be obtained from a soil test as well.
Finally, the site itself should be considered in determining the need for added nutrients. If the tree is by itself or in an ornamental bed with shrubs and perennials, the need may be greater than if in the middle of a lawn, as fertilizer pellets are commonly tossed into the mulch from prescriptive lawn fertilization in such scenarios.
The author is a horticulturist and certified arborist located in Omaha, Neb.