Rent Shop Volunteer Join

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?

Share

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
1 rating

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

QUESTION:

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?

ANSWER:

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

Lilac bush roots dangerous to house foundations
August 06, 2008 - Are lilac bushes dangerous to the foundation of a house? There is a lovely white-blooming lilac that grows against the house outside my bedroom window. My ex-husband said that the roots would destro...
view the full question and answer

Tecoma stans problems in Santa Monica CA
September 20, 2010 - I just purchased a mature 6ft tall potted Tecoma Stance Vine (Honeysuckle), It is placed in an area where it gets at least 3 to 4 hours morning/early afternoon sun and then a shaded sun for the rest o...
view the full question and answer

Problems with non-native Weeping Japanese Red Maple
October 04, 2008 - have a Weeping Japanese Red Maple. We bought if from a good nursery in the spring and planted it but now it is not red anymore. It is just greenish. Can you advise me what it is needing or any thing ...
view the full question and answer

Can non-native coleus grow in mulch from San Antonio
May 12, 2013 - Can Coleus plants grow in Mulch only?
view the full question and answer

Yellowing leaves on non-native globe willow in Las Cruces, NM
June 26, 2010 - I live in Las Cruces, NM. I have a good size globe willow tree. The leaves are turning yellow and brown dryness at tips and leaves are falling off. Does it just need water?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.