I recently had an opportunity to show off my garden to a few friends that are relatively new to the world of conifers. They exhibited all the responses that I have seen time and again for years. I find it quite amusing to hear educated people reduce their vocabulary to just a few one or two syllable words.
“Wow!” or its variant, “Oh, wow!”
And the very popular, “Ooooooo.”
Frequently as I give tours of my garden, people are at first amazed, and then very curious. Probably the single most asked question is, “How big will it get?”
How big will it get? An excellent question that seems to be increasingly confusing as more and more growers market their products. Some growers list basic information such as, “Grows to 25 feet” or “Matures at 25 feet.” Some growers provide an annual growth rate and a 10 or 20 year size. These are the most useful because conifers will never get to a certain height and just stop growing. If you look at the annual growth rate and the current size of the plant, you can make a fairly accurate guess on how old the specimen is now. With simple math skills, you may determine the approximate size of the plant in another 10, 20 or 50 years.
Since one man’s’ dwarf conifer might be another’s miniature, The American Conifer Society has adopted a very useful guide to help conifer enthusiasts determine how their plant may grow by setting up four categories:
Miniature = less than one inch per year
Dwarf = one to six inches per year
Intermediate = six to twelve inches per year
Large = Greater than twelve inches per year
A large growing conifer, such as the Douglas Fir (Pseudotsuga menziesii), a native forest tree in the Pacific Northwest, could be expected to grow more than 12 inches per year. (I’ve seen young trees put on two to three feet of growth in one year.) In contrast, the dwarf cultivar, Pseudotsuga menziesii ‘Little Jon’ grows approximately 3 to 5 inches per year. The native Douglas Fir will be well over 25 feet tall on its 20th birthday compared with the ‘Little Jon’ that will grow to three to five feet tall in the same time. Comparatively, the miniature Abies lasiocarpa ‘Duflon’ will only add one to two centimeters of annual growth making it well under one foot in the same 20 years.
If you have ever wondered why growth rates can be so varied for a specific cultivar, you must keep in mind that physical environments related to geographical location can greatly affect the listed annual growth rates. The grower in Oregon in near perfect conditions with ample water, great soil and mild temperatures is sure to see different growth rates than the gardeners in Syracuse, New York, Atlanta, Georgia or Minneapolis, Minnesota. In Oregon, the Douglas Fir enjoys one or two feet of growth per year while in Wisconsin it may grow 6 to 12 inches per year.
Conifers truly are amazing.
Thanks to my friends at Iseli Nursery for the photo link!