Saturday, March 13, 2010

Think Twice Before Planting More Holly in the Northwest

Area residents thinking about adding some form of Holly to your domestic garden display this year should consider it very carefully.

English Holly is an attractive plant at first introduction, but it wears away it welcome over time.

While the several types of Holly that are in the local area are not listed as an invasive species, it creates headaches for homeowners and heartaches for forest managers watching over the northwest’s’ most pristine forests.

It should be noted the English Holly and several other related species are not considered noxious weeds in Washington State. Most counties west of the Cascades, however, recommend their control and discourage planting.

Holly has more than a few positive attributes. Many people love the beautiful berries and the fact that it is an evergreen that lends color even during the drab winter grayness.

The berries of the European Holly are very attractive, but birds take them to other locations where they spread the plant from its intended domestic habitat.

It is those berries though that leads to a much wider problem. Birds eat the fruit and then completely process it in its natural habitat. (Translation...the bird poops it from the limb of a tree after acids make the seed viable). Holly is extremely adaptable. It can grow slowly in the darkness of a thick reproduction forest or at the base of a 400 year old cedar deep in a wilderness area.

Holly grows will in direct sunlight, but can also survive in the darkness of an unthinned reproduction forest like this example.

The latter is a problem for managers at places like Mt. Rainier and Olympic National Parks. Holly has been found in some of the most remote forests in Washington State.
The spiky, waxy leaves protect the tree from any natural predators so the it is left unfettered to grow where it takes root.

Residents that have Holly in their yard gain a fuming disdain for the tree over time as they try to manage it. Clipping one limb leads to the growth of many more in the same location. What should be a stately tree of holiday lore becomes an impenetrable bush of spiny leaves. The holiday romance of holly eventually disappears.

These residents have attempted to trim the base of their holly tree, only to find out that it sprouts back exponentially.

Removing Holly is a seemingly insurmountable task. Cutting the tree down will result in sprouts around the base. Pulling a small tree in moist soil may work eventually, but roots and debris left in or on the ground will surly sprout to form. Control may be achieved through an annual visit to pull the remaining parts of the plant. A larger tree will need the use of a pesticide after cutting. Applying herbicide freshly cut stump or a frilling method is most effective. Foliar herbicide treatment is not very effective due to the thick, waxy leaves. If you want to remove your holly trees with an herbicide, contact your local noxious weed control board for more information on the best methods.

We have learned from our mistakes and now its time to stop making them. While Holly has its own beauties and folklore, it has worn out its welcome here in the northwest. Gardeners should look for more environmentally responsible alternatives before adding more holly to our neighborhoods and yards. This is a tree that knows no boundaries and humans inflict little damage to the spread of this increasingly noxious plant.

Photos courtesty of GAP Photo


jo said...

Glad to see you are posting again! I love your blog and all the information you share.

Gregg P said...

I am just getting to the season where I get out and about a lot more. I do have another blog..related more towards photography... "Your World, My Eyes". Drop by there some time!

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