RESUME
Name: Bob Benjamin
Title: Horticultural consultant
Firm: M. Benjamin & Associates LTD, P.O. Box 66113, Chicago, IL 60666; (312) 617-8980; tooltree@core.com.

Do you have a response to this article? Send an e-mail to Todd Davis.

In about 2003 a group of arborists in the Midwest made planting depth a real issue. They argued that too often landscape trees are planted with surface roots too deep in the ground. They also stated that growers are often at fault. I caught up with Bob Benjamin, who has been outspoken on this issue, on the latest developments.

Q. When did you first notice planting depth was a major problem with B&B trees?

A. Planting depth has been an on-going problem for most of my career. However, in the early to mid-1990s it became more of an issue as people started to notice that the depth at which trees were planted dramatically affected their survivability.

Street trees were being planted too deep to accommodate tree grates and other urban paving. The '90s were a very difficult time for the green industry, particularly trees.

Q. How did you get involved in creating industry awareness?

A. I was talking with an old friend, Bernard Jacobs, landscape architect at Jacobs Ryan & Associates, a couple of years ago and we were lamenting that planting quality was not what it used to be.

We only seemed to be able to maintain the proper standards on our own projects and even that was becoming difficult as supervision became less common. There were too many conflicting standards, specifications and guidelines all attempting to meet the needs of the entire country.

We thought it would be good to write a guide to planting standards and specifications but on a regional basis for Northern Illinois. We talked to others in the industry and from that the Northern Illinois Specifications Review Committee was formed. We were about a year into our work when Ron Zillmer and Dan Trask came out with a popular presentation titled "Twenty Minutes in the Life and Death of a Tree." That really got the whole industry's attention.

Q. What was the overall reaction to the situation? Did growers feel like they were being blamed?

A. I believe that both liner growers and growing nurseries felt they were being blamed and some of this blame was justified. The good growers didn't feel threatened and were pleased that something was being done to raise the quality of the trees being supplied to the industry.

Q. Has awareness improved, and do you see planting depth as a lesser problem today?

A. Awareness has improved and to some extent it is a lesser problem today as it was in the past.

However, there is still a lot to be done. Planting depth is symptomatic of a larger group of additional problems.

Q. What are the biggest ways we can correct this problem?

A. Writing good, horticulturally sound and fiscally responsible standards and specifications for growing, handling, installing and maintaining landscape trees is a good start.

We need to develop a model for urban landscape trees.

We continue to attempt to apply the forest model to the urban landscape. This is a big part of our problem.

The forest model is based on high mortality and little to no human influence. Our model needs to be based on high survival and complete human involvement.

There are several research projects on plant depth in progress but none are far enough along for results to be published. Research has not been popular up until now. There are several new BMP (best management practices) publications that address this issue. Gary Watson at the Morton Arboretum is coordinating a lot of the research on these issues.

Q. Do you see this as primarily a nursery grower problem, a landscaper problem (poor installation) or some other type of problem?

A. I see this as an industrywide problem. The propagation, production, installation and maintenance of urban landscape plants should be viewed as a continuum.

Each segment relies on the previous to require a high level of quality. The real problems are low-bid contracts, poor specifications, lack of enforcement and value engineering.

When we say we want the best but accept less, then the problem is passed on to the end user. Each segment of the green industry must adhere to sound specifications and guidelines to supply a high level of product for the end user. We, and the end user, must accept no less.

Q. What effects could the increasing use of container trees have? What potential problems could this lead to?

A. I have never used container trees and don't feel qualified to discuss their use other than to say that the growing medium may be a bigger problem than circling roots. I must say I prefer planting bare root wherever possible.

Bare root has fallen out of favor over the years but it is seeing a revival, especially with financially strapped municipalities.

Q. What are the next steps we need to take regarding the root-depth situation?

A. Most of the better propagation nurseries, growing nurseries, arborists, landscape contractors and landscape architects are now focusing on this issue and changes are being made.

As this information continues to circulate within the industry and the public, continued changes will be made. That is the hope of the Northern Illinois Specification Review Committee -- that the overall level of quality will improve and our urban landscape will be the better for it.

One of the next steps is to incorporate these changes with an urban forest plant model into specifications and make those the industry standard.

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© 2002 Branch-Smith Publishing