Wednesday, May 2, 2007

Browning Evergreens in Containers in Brooklyn

My husband and I bought two potted evergreen trees in December of 2006 for Christmas and are trying to maintain them on our deck in Brooklyn with little luck. Right after the snow we noticed the trees started to turn brown and loose their needles. One tree lost a lot of needles very rapidly. The other maintained most of its color and most of its needles. Three weeks ago, in order to try and resuscitate the first and prevent further damage to the other, we decided to replant both in slightly larger pots. We have been watering them at least twice a week and adding Liquid Grow Plant Food. It seemed to help during the first two weeks. The tree with the most damage was almost completely brown and then it made a slight come back with some small patches of green...a small victory for us. But presently it hasn't restored fully and stopped improving. The other tree is doing better than its neighbor. It is 95% green. The browning is in patches at the bottom of the tree. They both get the same amount of sun light from the North East and I still water them at least twice a week although these last few days I didn't because of all the rain. Is our little brown tree too far gone to make a come back and what can we do to make sure the same doesn't happen to our other? Any advice you can give us would be much appreciated.
What you have in your containers are two dwarf Alberta spruce (Picea glauca ‘Conica’). As you see them all over the city, they are popular ornamental trees for containers because they are slow growing and hold that very formal, conical shape. They require full sun and, especially in a container, supplemental water.

Looking at your pictures, I am sorry to say that the one on the left is not going to come back for you. Of course there are always exceptions in the plant world, but to generalize evergreens do not bounce back as easily as deciduous trees, shrubs, or perennials. For deciduous perennials, trees, and shrubs, there are dormant leaf buds that can sprout and provide foliage even after a plant has been cut back. Evergreens grow from their tips out, and usually do not have the same kind of dormant buds. Some evergreens can be pruned lightly to push out more new growth, but by and large evergreens will not put out new growth on a branch that has already dies back.

Therefore, the tree on the left is not going to bounce back – it is best to simply start over. As far as the one on the right, you can prune off the brown branches at the bottom, because again, they are not likely to needle-out again. Evergreens, again, in general, naturally prune themselves from the bottom up if they are under stress. This is typically a response to not getting enough sun – and I have seen it happen on Alberta spruces plenty. Keep it in as sunny a spot as possible, continue to water regularly, and hopefully you will not loose any more of the needles. Next, look at the tip of the branches. If you have new green foliage emerging from the tips then you can rest assured that the tree is still healthy and going to do well this summer.

As far as what killed the other…? It could have been not enough sun. It could have also been not enough water, because you really have to keep containers irrigated constantly. Lastly, reexamine the space. Sometimes there may be a draft or an exhaust fan that we don’t pay attention to that is drying out a plant and/or container faster than we realize. Without being able to see the space, I would go back to guessing it is mostly a sun issue, and even though it may be bright, sticking a plant in that corner might not be the best option unless you know it to be more shade tolerant.

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