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Trees – ANLA Standards

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ANLA Illustration
Comparing nursery trees involves many different measurements, not just height. Illustration courtesy of American Nursery & Landscape Association (ANLA)

How to Comparison Shop for Trees

Counting sheep to relax yourself isn’t nearly as effective as plowing your way through the American Nursery & Landscape Association (ANLA) American Standard for Nursery Stock, a 129-page book that explains in detail how woody plants should be priced and graded. As dull as this book may be, it’s full of charts and diagrams detailing exactly how to classify each type of woody plant and then grade it. Understanding these standards is essential for nurserymen who buy and sell trees sight-unseen.


Back when we had a retail nursery we got many calls from people shopping for nursery trees over the telephone, and after asking the price they ask “how tall is it?” It’s an obvious question, but the answer can be very misleading, because most types of trees are not bought, sold or priced by their height. Nursery professionals classify tree size by trunk caliper (diameter of the trunk six inches above the ground) or by container size, and which standard applies will depend on the type of tree. They also refer to trees by their botanical (Latin) names, since common names aren’t specific enough to tell what kind of pedigree a tree has.


The best way to compare trees is to physically see them. There are so many variables that affect price, it’s impossible for the average consumer to judge and compare trees over the telephone. For example, let’s look at the popular ornamental pear tree “Cleveland Select”. This tree is often sold “container-grown”, in which case it would be priced by pot size. However, a five-gallon container-grown pear tree could range from a one-inch caliper to over two inches (twice the size). It could be a “whip” with no branches at all and still be eight feet tall, or a nicely branched “lollipop” shape only six feet tall. A field-dug “balled & burlapped” (B&B) pear tree could have a nice thick trunk and well-branched crown, but too small a root ball to survive transplanting.


Smaller size B&B trees are often “hand-dug” with puny root balls. Machine-dug root balls typically have a sturdy wire basket crimped around them to hold the roots together, but the root ball size can vary widely. ANLA standards dictate the proper root ball size for each caliper tree, and it can vary by species.

There’s also the question of tree structure. Young trees must be carefully pruned to remedy structural defects and encourage healthy, shapely growth habits. Some nurseries routinely shear tree crowns to encourage a bushier appearance, and some don’t. Nurseries vary widely in how carefully they prune, how high the “limb up” shade trees, and whether they control tree diseases.

The complex ANLA standards allow nurseries to classify trees by a uniform and industry-wide grading system, so long as nurseries are honest about judging their own product. Over the years we’ve learned that it’s best for us to physically see and select each tree we buy, rather than depend on someone’s description. We literally “skim the cream” from large nurseries by selecting the best trees from rows of hundreds or even thousands, picking only the best examples. To do this by phone requires trust; nurseries who follow ANLA guidelines are a better risk.


Organizations like the ANLA are very helpful in setting industry standards. Written bids and specifications depend on well-respected guidelines to establish a “level playing field” for competitive bidding. For the homeowner this is way too much detail, but it’s important to understand that simply comparing the height or container size won’t tell you much about tree quality. No two trees are alike. Getting expert advice in person from a trusted nurseryman is the best way to get your money’s worth

Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are on the “Garden Advice” page at www.goodseedfarm.com. For more information is available at www.goodseedfarm.com or call GoodSeed Farm Landscapes at (937) 587-7021.

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