We’ve decided to add on to our deck this fall. At our house, that means countless trips to the big box hardware store to pick up a different tool, another bracket or more wood. Since I can only look at 2 x 12s so long, I usually find myself wandering off to the garden center to poke around instead. Most of the time I’m oblivious to the conversations around me, but this past weekend I happened to overhear one that really bothered me.
A young couple approached a salesperson to ask advice about purchasing and planting some bushes for their new home. They were young and you could tell that this was their very first home and their very first landscaping experience. They needed advice, they needed to save money and they were sure that this would be the place to do both.
The back of this particular store houses their clearance stock — mostly plants that are past their “prime” and holdovers from spring and summer sales. (I spend a lot of time in this section! If you know your plants, there are some great bargains to be had.) Keeping budget in mind, the couple had started looking there first and had staked out several potential plants to purchase. Calling over the salesman, they asked his advice about the plants they had chosen — and that’s the point at which the conversation really caught my attention.
Pointing to three rather overgrown and underloved yews, the young couple asked if they would work for the north side of their house. “Of course,” the salesman replied enthusiastically. “They do fine on the north side and this is really the best time of year to plant evergreens. You’ll be getting a real bargain.” Unfortunately, the clerk gave his customers some half truths which encouraged them to make a poor purchasing decision.
Autumn is an excellent time to plant many, but not all, trees and shrubs. Knowing which species to plant, when to plant them and how to take care of them can help ensure fall landscaping success.
A plant’s growth pattern, especially how its roots develop, is a major piece of the planting puzzle. Root systems have several purposes:
- They anchor and support plants in the soil.
- They absorb water and nutrients from the soil to feed the plant.
- They store nutrients for later absorption.
- In some cases, they are essential to plant reproduction.
Iowa State University, a leader in the field of horticulture, divides the roots of deciduous and evergreen trees into the two basic categories of woody and non woody. Woody roots are the large, primarily horizontal roots that form near the tree’s root collar. Although their main purpose is to anchor the tree, they also supply it with some water and other nutrients. Originally, they are found between 8 and 12 inches below ground, but as the tree grows, these roots may become exposed. Woody roots extend well beyond the drip line of the tree, in some cases as far as 7 times the drip line.
Non woody roots are the roots found in the upper levels of the soil, usually the first 4 to 6 inches. The main function of these fibrous feeder roots is to supply water and essential nutrients to the tree and to store carbohydrates which are necessary for drought tolerance. They also extend beyond the drip line of the tree.
Some varieties of trees, maple and ash, for example, tend to always have a fibrous root system, while others, oaks, walnuts and spruce, have tap roots when young. Favorable soil conditions in the first few years of growth may encourage tap roots to extend downward, but eventually a tap root becomes less recognizable as the root system expands outward. Contrary to the common misconception, a tree’s root system is much more horizontal than vertical. Healthy trees have over 50% of their root systems in the top six inches of soil (ISU Forestry Extension), which explains why massive trees can be felled by windstorms.
Another piece of the planting puzzle revolves around the environmental conditions into which the fall planted tree (or shrub) will be placed. Soil type, access to oxygen, soil and air temperatures and availability of moisture are all factors in success or failure. Clay soils will restrict root growth as well as access to oxygen. Sandy soils will encourage horizontal growth, but the roots will be less fibrous and thus less able to pull in moisture and nutrients. Too much mulch will draw roots too close to the surface putting the tree at risk during dry spells.
Fall soil and air temperatures can lend themselves to planting success. Newly planted trees and shrubs often dislike the protracted, intense day and night heat and dry winds of summer. They struggle to produce enough energy to develop roots and support foliage at the same time. Fall in the midwest tends to have temperate days, cool but not cold nights and moderate rainfall, all of which combine to produce an almost perfect climate for planting. Even though the tree top is going into dormancy, the root system continues to rapidly expand and develop until frigid weather arrives.. (Horticultural research shows that trees and shrubs are capable of root growth in soil temperatures as low as 45 degrees F.)
A final piece to the puzzle of fall planting tends to be the species itself. Some plants simply prefer spring over fall planting. Although no definite reason has been determined, horticulturists at Iowa State speculate that planting success may be tied to the plant’s type of root system. According to them, “plants with shallow, fibrous roots can usually be planted with greater ease than those with fewer, larger roots.” Magnolias and tulip trees have large roots and are difficult to plant in the fall. Another theory says that some species are unable to take up adequate water until new roots systems are formed. Fall planting does not allow enough time for that to happen. Bur oaks and willows fall into this category.
Regardless of the reason, birch, sweet gum, bald cypress, fir and some varieties of oaks are among those varieties that are slow to establish and are more successfully installed in the spring. Narrow-leaved evergreens like yews and hemlock are recommended for spring planting, as are the broad-leaved evergreens rhododendrons, azaleas and boxwood.
I’ve thought about that young couple and the clerk several times this past week. It would be very easy to vilify him and assume he was just pushing a sale at the expense of the kids. Realistically though, I would guess that he was simply telling them what he thought was true. Like so many other professions, the field of horticulture is constantly evolving. Working with trained horticulturists and designers, like those at Embassy Landscape Group, can save you the frustration and expense of a failing landscape and give you the satisfaction of creating your own personal, signature landscape.