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Getting answers at the Plant Clinic

Flowering crabapple
January 28, 2014

At any season of the year, the Plant Clinic of The Morton Arboretum is ready to help homeowners and professionals have lovely and useful gardens and healthy trees and plants.

By phone, by email, through the Arboretum’s website, or in person, the clinic’s two full-time staff members and 48 trained volunteers field calls not only from homeowners but from arborists, landscape contractors, municipal officials, and students. They helped nearly 10,000 people in 2013, with calls and emails coming from more than 473 different zip codes across the US.

Plant Clinic Manager Doris Taylor and Plant Clinic Assistant Sharon Yiesla also give frequent interviews to the media on plant topics, produce the weekly Plant Health Care Report during the growing season, and write an occasional column for the website of the Naperville Sun.

The staff and volunteers can recommend good trees, shrubs, and other plants for particular conditions; identify plants; and help with questions about insects and pests, soils, pruning, weeds, and many other topics. They can refer callers to a lab for soil testing or help them find a certified arborist through the Illinois Arborist Association.

If they don’t know the answer offhand, they’ll consult their files, their wall of plant books, the internet, and the extensive plant expertise of the Arboretum. Recently, for example, they helped a biology student figure out the meaning of the word “marsecence” (it’s the phenomenon of a deciduous tree, such as an oak, hanging onto its leaves through the winter).

A majority of those who walk into the clinic opposite the Visitor Center are members; other visitors must pay Arboretum admission. But sometimes there’s no substitute for bringing in a sample of a plant for identification or diagnosis or a bug that may be friend or foe.

Not surprisingly, May, June, July, and August are the busy season, although the clinic is open (with shorter hours) throughout the winter. “It depends a lot on the weather,” Yiesla says. A drought, an early warm spring, or a big storm can bring a boom in questions. If cold weather comes early in the fall, on the other hand, calls drop off fast.

The Arboretum has been answering questions about plants since its beginning in the 1920s, but a separate Plant Clinic was formally established in 1966. Today, the loyal volunteers get regular training to make sure they are always well informed. 

Answering Plant Clinic questions is “a game of 20 questions,” Taylor says. The staff member or volunteer will try to learn as many specifics as possible to give the best advice. Here are some tips from Taylor and Yiesla on how to make the most of a call, e-mail or visit to the Plant Clinic:

  • If possible, know what kind of plant you’re talking about. Be as specific as you can. For example, it’s more useful to say you have a yew or an arborvitae than to say you have an evergreen. If you have the tag that came with the plant, have it handy.
  • If you don’t know what kind of plant it is, examine it closely and be ready to describe it in detail—not just leaves or flowers, but stems, bark and branches. Taking a photo that you can e-mail or bringing in a sample will help enormously with identification.
  • To help with identification, bring in samples of different plant parts—the flowers or nuts, for example, as well as the stem and leaves. How the leaves grow on the stem is important information, so bring in a twig with leaves attached.
  • If you bring in a plant sample or an insect, seal it in a plastic zipper bag so there is no chance that a pest or disease might get loose and cause problems at the Arboretum.
  • Be ready to describe the conditions the plant is growing under. How many hours of sun does it get? How close is it to a sidewalk or driveway? Do you water it? Do you fertilize it? Can you remember when, how much fertilizer you used, and what the formula was? Have you used any chemicals on the plant? How old is the plant? What grows near it?
  • Think about conditions farther afield. Has a neighbor sprayed or treated his lawn? Has there been construction next door? Is your road salted in the winter? The effects of some stresses, such as road salt or drought, may not show up in a tree or shrub for months or years, so try to remember back a while.
  • When you seek a recommendation for a tree or shrub to plant, make a note of the conditions it will grow under, such as sun and soil, and the available space. Be sure to consider if there are overhead utility lines. The Plant Clinic can help you choose a plant that will suit your needs and thrive in your conditions.
  • Find an extensive library of tree and plant advice on the website or see the Tree and Plant Finder to learn about specific plants.  


The Plant Clinic of The Morton Arboretum is open from 11:00 a.m. to 3:00 p.m. Monday through Friday between November and March and 10:00 a.m. to 4:00 p.m. Monday through Saturday between April and October. Call 630-719-2424 during open hours or e-mail plantclinic@mortonarb.org.