Standards for Plastic Container Grown Trees
This fall AZT will have completed its third growing season changing over from wood boxes to plastic containers for 24”/#25 and 36”/#45 trees. The reception from our clients (landscape architects and contractors) along with our production staff has convinced us that we have made the correct choice. As we did when developing our propagation methods for Variety AZT and our Root Manage Program, we consulted the research literature, spoke with other landscape horticulture professionally (locally and nationally), and talked with the design community and landscape contractors prior to experimenting with plastic containers. Based on these searches and conversations we elected to follow the standards established by American Horticulture Industry Association (d/b/a AmericanHort an ANSI-accredited Standards Developing Organization).
We based our decision on 5 criteria: 1) that the plastic containers selected be well researched and had been extensively field evaluated in conditions similar to our growing methods; 2) they would readily integrate with our ongoing production quality control at AZT; 3) that they compliment and amplify the effectiveness of our Root Management Program; 4) that they maintain a physical profile, sufficiently similar to boxes, so that landscape architects would not need to revise their planting specifications and that contractors would not need to make costly modifications to their planting methods (planting hole size and depth, backfill etc); and 5) since we ship to states other than Arizona, we wanted our trees to adhere to a nationally recognized standard (American National Standard Institute (ANSI) is a federation of organizations, associations/ societies, governmental agencies and international bodies). The ANSI Standards addressed our concerns and had the added benefit of having been in existence for years (the first “Horticultural Standards” were published in 1923) and were regularly reviewed and updated (as needed) by a board consisting of nursery professionals. Revisions are submitted to a canvass list of horticulture-focused societies, associations, companies, individuals, and related government agencies for endorsement demonstrating “evidence of industry consensus” for meeting ANSI requirement for accredited national standards.
We continue to grow desert trees in 48” box containers. AZT will further evaluate the possible use of larger plastic containers for these trees. AZT and our contractor clients have concerns about handling plastic containers larger than #45, without causing damage during handling, transporting and planting. We will keep you updated on developments.
For at least 40 years landscape trees in Arizona (and throughout the southwestern US) have been sold and marketed on the basis of container size and caliper. Arboricultural research has consistently shown that tree durability and longevity is strongly correlated with the planting of trees with calipers that are appropriately proportional to their root mass (container size). The ANSI standards for plastic containers allow growers, like AZT, to grow and sell premium quality trees that are compatible with the design and planting practices that landscape architects and contractors have come to expect from our trees.
If you have any questions please contact Kevin (kevin@aridzonetrees.com) or Ed (ed@aridzonetrees.com) or call us at 480-987-9094. As always, we will keep you apprised of new developments and research in this area of tree production.
24" Box Height, Top Width, Bottom Width
20" x 24" x 18"
Weight 200 lbs.
# 25 Height, Top Width, Bottom Width
18" x 24" x 20"
Weight 200 lbs.
36" Box Height, Top Width, Bottom Width
28" x 36" x 26"
Weight 900 lbs.
# 45 Height, Top Width, Bottom Width
20" x 30" x 26"
Weight 500 lbs.
48" Box Height, Top Width, Bottom Width
38" x 48" x 35"
Weight 2,500 lbs.
Values listed are based on the average weight of trees grown in AZT’s mulch/soil growth medium per box/container size and are offered here as an estimate of the weight of trees by box/container size. They are intended to help shippers and contractors in determining the type(s) of equipment needed to transport and off load trees. The physical size of the tree (height, width, and caliper and corresponding root mass) will affect the total weight as each specimen grows. The increase in tree mass requires the appropriate minimum to maximum container size to assure high quality control. AZT plants meet or exceed the minimum requirements of the American Standard for Nursery Stock (ANSI Z60.1).
American Standard for Nursery Stock Box Size to Container Size Equivalents
1.1.3.7 Box size equivalents
For purposes of the Table 1, box size “equivalent” indicates that a box size may be specified in lieu of the indicated equivalent container class, and nursery stock in an equivalent box size shall be accepted in the trade as in conformance with a specification for container grown nursery stock in the equivalent container class indicated, and vice-versa. Boxes are not required to have volumes that are “equal to” or within the volume range of the indicated equivalent container class, or vice-versa.
Container Class Specification to Box Size Equivalent
# 20 = 20-inch box
# 25 = 24-inch box
# 45 = 36-inch box
# 65 = 42-inch box
# 95/100 = 48-inch box
Complete PDF of The American Standard for Nursery Stock 2014 edition ANSI Z60.1-2014
The American Standard for Nursery Stock (ANSI Z60.1) 2014 edition is published by:
American Horticulture Industry Association d/b/a AmericanHort
an ANSI-accredited Standards Developing Organization
2130 Stella Court, Columbus, OH 43215
614-487-1117
Reprinted with permission from AmericanHort. www.AmericanHort.org