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Saturday - July 26, 2008

From: Brooklyn, NY
Region: Northeast
Topic: Non-Natives, Container Gardens, Trees
Title: Failure to thrive of potted blue-green cypress
Answered by: Barbara Medford

QUESTION:

I received a small 14" potted blue-green cypress for Christmas 2007. Kept it in a bright window, not direct sun. It was doing great until two weeks ago when it started turning brown from the center. Not dry, just brown. Put it outside in its pot for more sun. It's getting browner by the minute. What is wrong with it? Can this little tree be saved? Thank you very much.

ANSWER:

We were puzzled about a couple of things: first, what exactly is a "blue-green cypress"? We were looking for a botanical name that might lead us to clues on what is wrong with your little tree. The closest we could come is xCupresscyparis leylandii, Naylor's Blue Leyland Cypress. The "x" in front of the botanical name is not a typo, it means this is a hybrid, and we know it is a non-native hybrid. This University of Florida Extension article Naylor's Blue Leyland Cypress tells us this is not a pot plant, but grows fairly rapidly and very large, requiring a large-scale landscape to fit in. We turned to our Native Plant Database, and found, among others, Cupressus bakeri (Modoc cypress) and Taxodium distichum (bald cypress). These are representative of the other cypresses listed, all members of the Cupressaceae family.

So, second question, what is one of these trees doing in a pot? These are all BIG trees. Furthermore, they are all conifers (cone-bearing trees) and have long, deep taproots. With a taproot like that, transplanting, even when they are quite small, is very difficult. If the taproot is broken in the process, the tree can quickly die. We're just speculating here, but we think what you got was intended as a seasonal decorative item, and never had any chance of growing or surviving much longer than it already has. When that baby tree's taproot hit the bottom of the pot, it began to decline. Putting it suddenly outside, without gradual seasoning, no doubt was the finishing touch. And, even had you transplanted that tree outside right after Christmas, it still probably would not have survived, since most of them prefer warmer temperatures than you would have in New York, although the USDA Plant Profile shows Taxodium distichum (bald cypress) growing in New York State. But it wouldn't be that particular tree, because it is one of the very few conifers that are deciduous, and drop their leaves in the Fall.

We're sorry we couldn't help you any more, and hope at least the pot was an attractive one you can reuse. But don't plant a cypress in it!