Should Landscape Architects be Experts in Plants and Soils? Dust-Up on LinkedIn

About a month ago, someone posting the following question to the ASLA group on LinkedIn:

In his book Up From Roots, James Urban criticizes our profession for not knowing basic horticultural Principles. Is this crit valid?

Over 50 responses later, some of them quite impassioned, and it’s clear that Jim’s book — and this question — really hit a nerve. (To read all the comments, you do need to be a memeber of the group on LinkedIn.)

Here is Jim’s response.

25 years ago, the Editor of Landscape Architecture Magazine responded to my request to submit an article on plants by telling me that “LAM does not publish plant related articles because we do not want to give people the wrong impression of what we do.” Fortunately that attitude has changed at ASLA.

I am not sure what landscape architects (LAs) actually do, but I am sure that we drawn plants on our plans. I rarely see any designs by LAs, even at the most schematic level, that do not include plants. With exception of the communication awards, ALL of the 2011 ASLA national award winners (design and planning award categories) include plants in the drawings or completed works. We are in the business of designing with plants.

We are also in the business of getting landscapes built. We may not think about it this way, but the process of building landscapes means that we are a critical part of the construction industry. We must understand the construction process and how our design ideas impact the product. We start creating the conditions that allow a tree to survive or die at the moment we place a tree circle on the plan. Each decision continues to determine the fate of plants at least until the end of the warrantee period. Better LA’s understand that we remain somewhat responsible for, and impact the life trees far into the future. The design of trees is not just about species selection, a detail or specification. Many other parts of the design will impact the trees health and all must be understood by the LA at each phase of design and construction.

What is Up By Roots Asking of Landscape Architects?

The thesis of my book is NOT that LA’s should become horticulturalists. Judging from the number of people in this LinkedIn conversation that admit to not having read the book, I can see how the thesis has been mis-interpreted. The serious discussion about plants is only about 48 out of 455 pages and does not begin until page 321. So relax and forget the horticultural idea. If you only know 10 trees and 20 shrubs, that is fine, just make sure you are expert with that limited pallet. In general, most horticulturalists do not try to be designers; similarly, we should not try to be horticulturalists.

The thesis of the book is: If you use a plant in a design you had better make sure that it will live and grow to the expectations of you and/or your client. I do not see many clients who would be happy with an oak tree that only lives 20 years or less, and languishes the entire time.

Professionals are considered experts in any area that we practice, or we are supposed to hire a consultant to assist us in areas where we are deficient. We need to be professional enough to know what we do not know. I believe that most people who hire LAs think we are expert in the use of the plants we put on our plans. In most states where we are licensed to seal planting plans. That means the state has been convinced that we are experts in this area of practice, that we know enough about plants to protect the public health, safety, and welfare. If we want to say we are the experts in this area we had better first BE EXPERT.

The limits of practice

One commenter in this group gave an interesting analogy comparing a general practice doctor and a brain surgeon. I totally agree, with one exception. A GP has studied the brain enough to know when you might just have a headache and when that headache might suggest a trip to the brain surgeon. As a profession, we are not at a comparable level of expertise. When was the last time most of us told our clients they needed to see an expert in plants or soils?

Some LAs do regularly hire consultants who are more expert than they are in the areas of plants and soils. This is quite acceptable as long as these experts are brought in at the earliest phases of the design. The consultant’s scope must include preparing the design for the soil and other growing conditions for plants. The LA must listen to them and follows their advice on areas of the project that impact plants and soils. That includes reviewing the size of planting spaces, soil volume design, plant spacing, and review of item such as lighting, paving, grading, and utilities. In short, all the things that LAs should be expected to coordinate to make sure that all systems function. If you just hire a soils person to “do the specs” it is still likely that serious omissions will occur.

Landscape Architects Can Become Expert in the Area of Soil

The key to healthy plants is soil design and Up By Roots is mostly a soil book. I challenge the concept that just using native plants or appropriate plants or having a great understanding of the plant parts above the ground, or expecting unusual maintenance, can overcome insufficient soil design or poor drainage. Does that mean that I am asking you to become soil scientists rather than horticulturalists or landscape architects? No! I just want to LAs to have a minimum understanding of the growth requirements for any plant they use and to make sure that they have provided for them. Species-specific soil requirements are in Michael Dirr’s book Manual of Woody Plants and easy to research.

I believe that the basic principles of soil and drainage design can be mastered by our profession. For special or overly complex soil problems, adding a soils expert to the team is a good idea, but for the average project — a residence, the shopping center parking lot, a small plaza, or a small section of streetscape — we should be able to know the basics and be expert enough to solve simple soil and tree planting problems. That is what Up By Roots is saying and I wrote it with the idea that it would be a reference book to lead LAs through this process.

Am I bashing ASLA?

I am not bashing LAs or the ASLA. I have a deep commitment to both our profession and our Society. I have been a member since 1969, was the president of my chapter, and have contributed untold hours of time to the society. I do speak out when I see things that are damaging the credibility of the ASLA and the profession even when it means being critical of fellow professionals or the society. I believe that I was made a Fellow in part for that activism. I try to be rigorous about fact checking my own writing and apologize on any occasion where I may be wrong.

But “Landscape architects are artists” and “it’s a broad profession”!

Several people noted that LAs are artists and suggest that form and ideas are more important than these sticky details such as plants dying. A good artist knows enough about the materials they use to not have the art fall apart. The list of this profession’s projects with failed soil and trees is far too long, including many ASLA award winners. If trees are part of our artistic medium then we need to understand the systems that make them grow. Some of our best designers do produce fantastic projects that work on a technical level as well as an artistic one. Peter Walker’s 9/11 Memorial is one good example.

Several commenters also noted that Landscape Architecture is a broad profession that requires educators to teach many skills. I agree. But if your school is in a state that allows landscape architects to seal planting plans, you must teach planting design AND their important soil requirements. This is a core skill and we have lost it at many levels. I have seen a bit of improvement in this area at some programs. But the schools cannot absorb the entire burden, and I believe continuing education by ASLA is also critical. I am pleased that over the last 10 years the ASLA Annual meeting has gone from almost no plant and soil sessions to so many that last conference I could not attend them all. Good work, ASLA.

Miscellaneous issues

The science behind all this is quite exhaustive and covers a broad area of study.  ISA, which published my book, is quite demanding in the scientific review of its publications, which are all peer-reviewed.  Concepts have to be supported by research.  For example my 1985 original study, which began to document the extent of the tree problem, looked at 1100 individual trees in 11 projects. ISA’s journal, Arboriculture and Urban Forestry, contains many research studies each year that are directly relevant to landscape architecture practice.  Arborists are the group that LAs should partner with and can learn from.  Please bring arborists as well as soil scientists into your practice.

I am not an ISA Certified Arborist, just a guy who reads their work and listens to them. I have no web site, Twitter, or Facebook page.  It took this discussion to get me on to LinkedIn.  The best way to find me is on email — [email protected]

Please read the book, continue the discussion, move the discussion from plants to soil and become expert in any area of this great profession that you choose to practice.


  1. Gillis Dellebeke

    I enjoyed your comment James. Go on with your work.

  2. this issue is always discussed amongst la’s …..and i suppose it will continue on and on …..great summary…..

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