Native Plants

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

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

2 ratings

Thursday - July 02, 2009

From: Greenville, SC
Region: Southeast
Topic: Compost and Mulch, Diseases and Disorders, Trees
Title: Problems with Eastern hemlock in Greenville SC
Answered by: Barbara Medford

QUESTION:

Dear Mr. Smarty Plants, I have a beautiful, young, 5 and a half foot tall Eastern Hemlock. I purchased and planted it two years ago in the fall. It has been doing very well all this spring. And new growth is everywhere on it; it is thriving. But now, I have noticed that this June, when you brush up against it, the needles fall off. At least a third of the needles have fallen off. There are no Hemlock Adelgids once so every on the tree, so it puzzles me that there is such a huge problem on my tree that has nothing to do with adelgids. Last year, i had to water it a lot because of the severe drought, it persevered even though it was still in shock of being transplanted. I thought that if it could survive such a horrible drought, it could survive anything once established like it is now. I noticed in early spring, that one branches leaves started to fade. Nothing happened to them, but instead of being that lush green, they became more of a tannish green. After many days of staying inside because of so much rain we are having this year, I came out on a dry day to check the tree's foliage, and it fell off and I also noticed a minor sap leak at the base of the tree. (I thought the leak was from it growing so fast for a hemlock, kinda like growing pains) Now, there is a thin layer of needles in the leaf litter and the foliage is still coming off, parts of once full and lush branches are now bare, and there are still no bugs. I have always heard that Hemlocks love fog, rain (especially light drawn-out rain) and most importantly, shade with room to grow. The hemlock is 40 ft from the northern side of our house Receives 4 hours of sun on a sunny day Receives plenty of water Has a clay-loam soil (all benefits of clay and good drainage on clay loam!) Has tons of protection from wind Has 100+ ft tall white oak above it that doesn't have any leaves below 90ft (and we didn't ever prune the oak) I just don't understand what is happening to it! Can you please help my Hemlock! I just wish I could at least know whats going on so that i could have a chance to help it

ANSWER:

As we researched your question, we realized that Tsuga canadensis (eastern hemlock), which is native to South Carolina, is a pretty finicky plant. When you have a plant having unexplained problems, you have to look at the environment of the plant, not just now, but for the last couple years. If you purchased the plant from a nursery in a pot, and transplanted it into the native soil, the roots may have just now (since it's been planted less than two years) gotten in contact with that soil.

Here are the Condition Comments on this plant from our Native Plant Database:

"Conditions Comments: Eastern hemlock can be a fast-grower, but is more often slow-growing. It must be placed where there is good drainage and no strong, drying winds. Trees seem somewhat pH adaptable but prefers acidity. They can be restrained as a hedge for years with regular pruning. Sunscorch kills back branches, and drought kills the tree. A number of diseases and insects can be troublesome, but trees in good health prove reliable."

There are several clues in those Comments, possibly the most telling one is "drought kills the tree." The conditions that the tree has had to withstand last year and this year would be a trial to any plant, especially a young one like that. First, it was drought, now, this year, it's flooding. Are you sure you are getting good drainage? What is generally called "clay loam" in soil analysis is about 25% clay, 30 to 50% silt and the rest sand. This is not necessarily a particularly fertile soil, and probably not well-draining. If you were watering it heavily last year, and the drainage was not good, the roots could have been drowning last year, and are really drowning this year. It prefers acidic soil, and needs part shade (2 to 6 hours of sun a day) to shade (less than 2 hours of sun a day. We tried to ascertain if your soil was acidic or alkaline, and couldn't find any indications either way. Sometimes plants which need acidic soils but are planted in alkaline soils become chlorotic, losing the green color in their leaves.

Read all of this Ohio State University website Tsuga canadensis, which details the many problems of the tree. Especially, we noted this excerpt from that site:

"Canadian Hemlock is somewhat sensitive to being transplanted in Autumn, and care should be taken to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray, to enhance survival chances during the first Winter."

We found a list of hemlock stressors, or insects and diseases: hemlock wooly adelgid (Adelges Tsuga Annand), elongate hemlock scale (Fiorinia externa), hemlock looper (Lambdina fiscellaria), spruce spider mite (Oligonychus umunguis), hemlock borer (Melanophila fulvoguttata), root rot disease (Armillaria mellea), needlerust (Melampsora parlowii). If you examine these linked websites, perhaps you will recognize some of the symptoms you have detailed for us.

Bottom Line: Since we are gardeners, not entomologists nor plant pathologists, we can't possibly diagnose the problem(s) from a distance. Furthermore, our soils are very alkaline in Austin and we're in extreme drought, so there would be no possibility of a hemlock flourishing here. Best guess: We think your tree was in trouble from the time it was planted. It probably should not have been planted in the Fall, the soil needed extensive amendment to improve drainage, and a raised bed would have been better still. Working compost into the soil, mulching to protect the roots and checking the drainage of your soil could help, but too much damage may have already been done.

If you would like to try to save your tree, we suggest you contact a trained and certified arborist to look at it and determine what, if anything, can be done. You might contact the Clemson University Extension Office Greenville County for information and possibly a list of experts that could help you.

Tsuga canadensis