Selecting Evergreens for your Landscape and Gardens
Matching the evergreen species and variety to your soil, sun, wind, climate, region and space is extremely important to the health and life span of your evergreen. Most evergreens live a very long time and you certainly don’t want to lose one because it won’t thrive or grows too large for its space. Planting an evergreen is not terribly hard work, but digging one out certain is. Not to mention losing several years growth on a mistake and starting over with a small young replacement.
SELECTING EVERGREENS
There are so very many evergreens to choose from when planning your landscape or foundation plantings. Of course you will need to consider the size you need for the space available, but next there are a lot of decisions to make. Do you want tall? rounded? Conical? Columnar? Spreading? Arching? And then there is color. How about blue? Green? Yellow? Burnished gold? Because there is such an enormous variety of evergreen characteristics to choose from you may want to do quite a bit of browsing before making selections. You will find extensive descriptions and photos on this site, and each region may a different selections available that are not listed here. So spend some time here, online, looking at catalogs and browsing local nurseries. And although the old stand-bys may be hardy and reliable, you just might find something a little more interesting!
The most important think to look for when selecting an evergreen tree is the root system. Although it is quite difficult to do when you cannot see the roots inside the container. If the root system is strong and healthy it will support vigorous growth once replanted. Typically if the plant is full, green and healthy looking the root system is strong. Look for well shaped evergreens. If it is supposed to be a broad cone shaped do not select one that is a narrow column, but of course a healthy specimen will develop a natural form once planted. Misshapen or damaged plants should be sold as a lesser grade at a reduced price. You will likely see slightly larger plants in slightly larger containers at a slightly higher price. There is no need to buy a large evergreen. Most will catch up quickly once established. The only reason I can think of for spending more money for a slightly larger plant is if you are working on curb appeal to sell your home.
Certain regions may have excessively high or low pH levels. Although most evergreen conifers prefer at least a slightly acid pH, you will find that certain species and varieties either thrive naturally in your region or have adapted. Be sure to ask when you purchase evergreens if your selection typically tolerates local levels of pH. Testing your soil and amending it to alter the pH will do little good, in a couple of years the soil always reverts to its original state. Using a fertilizer each spring that is formulated for evergreens will usually be enough to prevent iron chlorosis, which is a yellowing of the foliage due to a lack of acid. If soil in your region tends to have a higher pH (alkaline) there are several selections that tolerate alkaline soil very well, including Arborvitae and Colorado Blue Spruce.
PLANTING SITE SELECTION
Most evergreens prefer full sun but can often get by with a little shade. The evergreen will not grow as quickly and vigorously in part shade, but in general should remain healthy and grow at a slow but steady pace. Some species and varieties are much more fussy about sun, so be sure that the site you select provides enough.
Good drainage in your soil is very important so the roots able to take in not only moisture but also oxygen. Clay soil will hold plenty of water but not allow water to drain so that oxygen will be available in the air pockets between soil particles. Sandy soil allows for plenty of oxygen but lets the water drain right through before the roots can take in enough water. To determine if your soil will drain water appropriately, dig a hole (which can later be used for your plant) and fill it up with water. If the water has not all drained into surrounding soil your plant roots will drown. If you are not able to fill the hole up because the water immediately drains, water will not be available to the roots. Either way, you will need to amend the soil. Dig your hole much wider and mix in plenty of compost, shredded leaves, and/or peat moss. All of these natural amendments will improve the drainage and the texture of your soil.
LIFE SPAN AND GROWTH RATES
Size categories of conifers:
In an effort to standardize terminology throughout the industry, size categories have been created. This does simplify size references, but not all segments of the industry are in agreement. Nonetheless, the list that follows does clarify what you can expect if an evergreen is labeled as miniature, dwarf, intermediate or large.
Note that mature size is at 10 years growth, a standard in the nursery industry. Also note that a dwarf sized plant is a general category term. A true dwarf is any evergreen that does not reach the height of its parent at maturity, in this case dwarf is a cultivators term.
Miniature:
Mature size at 10 years is 6-10”
Ultimate size is less than 3 feet
Growth rate is less than one inch per year.
However, the miniature category is listed as 2 to 3 feet at 10 years and grows less than 3” per year by the American Conifer Society.
Dwarf:
Mature size at 10 years is 2 – 5 feet
Ultimate size is 10 to 25 feet.
Growth rate is 2-6” per year.
Intermediate:
Mature size at 10 years is 5 to 15 feet.
Ultimate size is 33 to 50 feet.
Growth rate is 6 to 12 inches per year.
Large:
Mature size in 10 years is 10-25 feet.
Ultimate size is over 60 feet.
Growth rate is 12” per year.
Growth rates can be influenced by many factors: planting site; soil conditions; specific species; available water; fertilization. It is very important to remember when selecting evergreens that the nursery tags always list the mature size at 10 years, but almost never tell you how large the evergreen will be in 20 or 30 or more years. If you have not adequately researched the selection you need to assume that in 20 years time the evergreen will be at least double the 10 year size. Also note that large evergreen trees can often live for 100 or more years! Imagine how big it will be then.
A note about dwarf conifers: the intent and purpose of a dwarf is to be small of course. So generously fertilizing a dwarf not only defeats the purpose of purchasing a dwarf, but will shorten the lifespan by encouraging unnaturally fast growth. That, actually, is true for any plant that is over fertilized.
Generally life span will be relative to the growth rate of your evergreen. A slow growing evergreen will live longer.
Be sure to check the plant details and photos for more specific information about each species and variety.