P&PDL Picture of the Week for
August 17, 2009

Holding Nursery Stock

Mike Mickelbart, Assistant Professor, Horticulture & Landscape Architecture, Purdue University

As summer progresses and typical seasonal droughts occur, holding nursery stock becomes more difficult. The three examples shown will be very difficult to maintain through dry conditions because of the massive canopy volume to root volume ratio. There are a few things that should be considered with regard to holding nursery stock. First among these is to be sure to accept only those plants that meet the American Standard for Nursery Stock (ASNS) guidelines. The red oak shown in the first picture came in as a 2½“ caliper tree. According to the ASNS standards, the minimum root ball diameter should be 28”, however, the actual root ball diameter of this tree is 22”. The linden shown in the second photo came in to the nursery as a 1¾“ caliper tree, which should have a minimum root ball diameter of 22”, but instead had a root ball diameter of 20”. In both cases, it will be very difficult to keep these trees sufficiently watered throughout the summer. The burr oak shown in the third photo came in as a 1½“ caliper tree with a root ball diameter of 20”, which corresponds to ASNS guidelines. However, because the tree was held over the winter, the caliper is now 2”, so the small root volume again will be difficult to keep well watered. These trees highlight the need to 1) only accept stock that meets ASNS standards and 2) avoid holding balled and burlapped stock for long periods if at all possible.

The ASNS guidelines can be downloaded for free:

Click image to enlarge

Red Oak


Burr Oak


Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service