En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
Not Yet Rated

Thursday - July 03, 2008

From: Tacoma, WA
Region: Northwest
Topic: Non-Natives
Title: Yellowing leaves in non-native Arbutus unedo in Washington
Answered by: Barbara Medford


I live in the Pacific Northwest and have planted 2 dwarf strawberry trees. I have been giving them lots of water. Their leaves are turning yellow. Am I watering them too much? Not enough?


What's going on in Pierce County, Washington? This is the second question today from people who planted non-native trees there and now have yellowing leaves on them. So, let's address the problem with your Arbutus unedo, dwarf strawberry trees.

Because your trees are native to Ireland, southern Europe and the western Meditteranean, we have no information on it in our Native Plant Database. Instead, we went to this USDA Forest Service Arbutus unedo; these USDA sites are usually pretty impartial about discussions of plants and the locales where they can do well. The map of distribution of this plant showed a small area around Puget Sound where the strawberry tree can be found. Since that's where Tacoma is, we're assuming you're in the right place.

Yellowing leaves on a tree usually indicates chlorosis, or the loss of chlorophyll in the leaves, which makes them green. This happens most often when an acid soil-preferring tree is planted in an alkaline soil. The plant needs the trace element iron from the soil, and in alkaline soils the iron may be inaccessible to the plant roots.

In the West, many plants don't get enough iron because their roots are unable to obtain it from the soil. Roots may be damaged by a lack of oxygen in overwatered or poorly drained soils--typical after a rainy spring--or by extreme soil temperatures. High concentrations of limestone (calcium carbonate) make the soil more alkaline, which makes the iron less soluble. The information we found on Arbutus unedo indicates that it "tolerates" alkaline soil and clay, but "prefers" sandy, slightly acid soil. And, too much water around around the roots in a clay, poorly-draining soil may also harm the tree's capacity to utilize iron from the soil.

So, you asked if you were watering too much? Probably so. To help amend the soil to a more acidic nature and better draining texture, first, add some iron tablets to the soil. Then, trying not to damage the roots, get some organic material, cottonseed meal, etc., in the soil around the roots. Mulch heavily with an organic mulch like shredded hardwood. This mulch will hold in the moisture, help keep the roots cool, and decompose slowly, adding to the organic material in the soil, again helping to neutralize the effect of the clay soil. If, when you water, the water pools on the surface and remains for 30 minutes or so, you are definitely dealing with poorly draining clay soil. Taper off on the watering, and try to create a better-draining environment for the roots.


More Non-Natives Questions

Fragrant native plants for San Antonio, TX
August 19, 2009 - I live in San Antonio, Texas, and I am re-landscaping my backyard after my dog ate some of the beautiful blooming oleander and had to spend some time at the vet's. My backyard is my sanctuary, and it...
view the full question and answer

Plants (mostly non-native) not common to Tyler TX area
July 11, 2009 - I live in Tyler, TX 75705. I always seem to fall in love with plants that are not common for this area so I cannot find information on growing these plants in this area: Esperanza, Alstromeria, Japan...
view the full question and answer

Problems with non-native closet plant
November 23, 2008 - I have three closet plants. All are putting on new growth and even blooming. However, the leaves are turning brown from the edges. What is the problem?
view the full question and answer

Problems with non-native althea in Georgetown, TX
June 20, 2009 - My white althea's leaves have a white edge, last year the bloom did not open. Is it sick?
view the full question and answer

Suckers on non-native crape myrtle in Bay Point CA
July 22, 2010 - How can I stop suckers on a Crepe Myrtle tree? I have bought sucker stopper in the past, but find it hard to locate now. Is there something else I can spray or paint on the base of the tree to stop ...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
© 2015 Lady Bird Johnson Wildflower Center