Selecting a Tree to Plant

Spring is just around the corner and you are determined to plant a new tree. How do you make a good decision? What IS a good decision? We are often asked for suggestions on species to plant. It is never a quick or easy answer. Please note: Although I am referencing trees here, this information is applicable to pretty much any perennial plant.

There are many factors to consider prior to hitting your favorite nursery. By the way, “your favorite nursery” will be the one that has the tree species you want, of high quality, at a price you are willing to spend.

Pull up a comfortable chair, pour yourself a cup of tea … this may take a while.

Final species selection is determined by various criteria involving site characteristics, your environment and climate as well as your own personal preferences and tolerance levels. Buying that popular tree everyone has been talking about may, or may not, be a suitable choice for your property.

Before you decide what you are going to purchase you need to go through a check list which will limit what you can plant and expect it to survive. There is nothing more frustrating than to plant a tree, have it do well for a little while and then decline and die. Trees take a long time to grow and mature; you want to do everything you can to ensure circumstances are going to make that possible.

Where are you going to plant it?
You need to determine where you are going to plant the tree. No, “in my yard” isn’t a sufficient answer.

Site characteristics affecting your choice include space for it to grow to its full potential. Ok, that sounds so obvious it wasn’t even worth mentioning, right? I cannot tell you how many people call us to prune a tree that has “outgrown” its spot because the people had “no idea how big it would get”.

First of all, this is not the tree’s fault and second, size information is readily available from the internet, local nurseries and arboreta. Take the information seriously. If reliable sources say a tree has the capability of getting 30 to 40 feet tall and you have no perception of what that actually means, consider a two-story house with a peaked roof is approximately 25 ft in height. If that height potential makes you uncomfortable, select a tree which will max out smaller. Thinking you can “keep a tree small” by pruning is setting yourself up for a high maintenance situation which translates to high expense and is unnecessarily stressing the tree through repeated wounding.

It is not a bad idea to take a drive around town or your neighborhood to see who has what planted. But a cautionary note about getting information from homeowners. My sincere apologies and I don’t mean to offend anyone, however, homeowners, unless they are arborists and, unfortunately even then, are not necessarily reliable resources as to what species will do well in your area. Too often they fail to take into consideration extenuating circumstances such as soil characteristics and properties, planting practices or the quality of the specimen purchased which may all limit survivability or growth.

Back to your criteria. In addition to your comfort level on height, the tree requires the sky above it be clear of conflicts. Do you have overhead utilities? Look up! Do not plant a tall tree under utility lines whether they are house lines or main lines. This will also cause it to become a high maintenance nightmare with the very real probability of your tree being disfigured to accommodate those lines. Even if pruned away from the lines, it remains a hazard to those lines during storms, possibly disrupting your service in the case of house lines and affecting your neighborhood in the case of main lines.

Utility companies generally will not prune trees under house access lines; that is the consumer’s responsibility. They will typically prune trees under major access lines. Some people have the impression this is a free service, when in fact it costs all of us money in higher utility rates. Be responsible and do not plant anything growing over 15 ft under any main utility line. I know recommendations allow up to 20 ft, but trees outgrow their potential all the time. Play it safe. Plant a shrub if you absolutely must have growth in that area.

In addition to height potential, consider how wide will the crown get. Look at those plant specifications again. Again, take it seriously. If the spot you are considering is fairly narrow, there are cultivars specifically created to grow upright rather than spreading. These may say “columnar” or “fastigiate” in their descriptions. These are excellent choices if you have limited space.

In addition to basic height and width of the tree, consider how big the trunk itself will get. Some trees may grow tall without putting on a great deal of girth and some can get massive.

A Lombardi poplar matured too close to a house.

You also need to consider the available soil space. Tree roots need room to grow just as much as the above ground structure of the tree. Do you have enough soil volume to support the root system of the tree you are considering? Some people think roots stop at the drip line, but that isn’t the case. Tree roots can grow much further than the drip line.

While you are looking into general characteristics of your potential tree, pay attention to what is said about the root system. Not only is available space necessary, but the root structure may have attributes you find less than pleasing in your yard. Some trees have strong lateral root systems staying very close to the surface. Some are oblique or heart shape, growing out and then down. Some species maintain their tap root through maturity, although the majority of species do not. Then there are many systems that are a combination.

Are there underground utilities you need to be aware of? CALL BEFORE YOU DIG! This is a requirement in many states and is not limited to professional companies. You want those lines to be significantly far away from the mature size of the trunk.

If you have a septic system and drain field, do not plant the tree on top of either the drain field or the tank. Tree roots will not create a crack but they can and will take advantage of one that appears.

Climate characteristics
When selecting a suitable tree to plant you need to consider as many aspects of the climate as you can. The United States Department of Agriculture (USDA) Hardiness Zone Maps are based on winter lows which tells you the probability of the plant surviving the winter.

The U.S. Sunset Climate Zones consider many other factors as well, including length of growing season, timing and amount of rainfall, winter lows, summer highs, wind, and humidity.

The American Horticultural Society has developed heat zone maps as well.

These all provide helpful information to incorporate with your onsite observations of your specific location. Are you mostly in deep shade because of large trees around you? Is your property exposed to substantial prevailing winds? Are you in a cold sink? Do you have an enclosed yard with a solid fence? How tall is the fence? The more detail you note about your site, the better choices you will make.

Soil matters – a lot
The type of soil and its characteristics may be the ultimate decider in whether your tree thrives, struggles or dies. These characteristics include pH, texture, infiltration and drainage of water. You also need to be aware of limiting factors such as compaction, salinity. Future blogs will be dealing with the importance of and how to maintain healthy soil.

You take all this information and compare it to the needs of the tree you are considering to determine if it is a “good fit”.

A lovely Autumn Blaze maple planted with ample room in a site with appropriate conditions.

What is its purpose?
Generally, when we plant a tree it is with a specific function in mind. Do you want future shade for a patio, the house, a specific room in the house? Do you NOT want shade to inhibit growth in your vegetable garden?

Maybe it’s purpose is to supply you with fresh fruit. Or to provide a focal point which will enhance the aesthetics on your property by providing colorful foliage or flowers or because you are intrigued by its unusual growth habit.

A weeping juniper adding year-round interest with striking growth habit.

You are narrowing down your choices. Do yourself a favor and be prepared with a few candidates. Your nursery may, or may not, have your first choice. If you are determined on a specific species, plan ahead and order it. Check with your nursery to determine their ordering schedule. Some place orders months in advance. Others may have stock coming in regularly.

Please see my blog on “Selecting a Quality Specimen to Plant” for further information before you buy.