Wednesday, February 17, 2010
Are white pines the favored evergreen?
John Arbogast
Landscape consultant John Arbogast answers your questions every Thursday. Send questions about your lawn, garden, plants, or insects to:
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Roanoke, Va. 24018
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Q: What’s happened to white pines? I’ve lived in Virginia for many years and the white pines don’t seem to be as strong as I remember them to be. With recent snow, they’ve lost a lot of branches. Are white pines no longer recommended? If not, what do you recommend as a substitute evergreen?
A: Nothing new has happened to white pines. People have just become more aware of the problems caused by this evergreen as it gets older -- pines that are 30 to 35 years-old or older.
Let’s explain some of the problems with white pines in the landscape.
The white pine is by nature a brittle, soft-wooded tree. Nature has made older white pines weak because of their tall, straight center trunk. Historically, this characteristic made white pines attractive to early explorers of America who envisioned using this tall, straight trunk for their sailing ships. Unfortunately these trunks are easily pushed to and fro by heavy winds.
Nature is also guilty of giving white pines poor structural resistance to heavy ice or snow load. Engineers know the importance of structural resistance.
The tree has a fairly wide-spreading root system, but no tap root to speak of to anchor the top as it gets older and heavier. Hobby and commercial landscapers probably like to install white pines since they transplant easily, but their lack of an anchoring tap root can become a problem in the pine’s later life.
Here in Virginia, the white pine doesn’t like our heavy clay soil. Clay soil is poorly drained during wet times and shrinks during dry periods. Soil shrinkage can impede root development as well as reduce oxygen available to growing roots.
I personally don’t recommend white pines anymore. As an alternative evergreen, I suggest one of the hybrids of Foster’s hybrid hollies where space is limited and a 25-foot tall, cone-shaped, leafy evergreen is suitable. Otherwise I recommend one of the varieties of the leafy evergreen American holly where a large-growing evergreen is desired.
A: Nothing new has happened to white pines. People have just become more aware of the problems caused by this evergreen as it gets older -- pines that are 30 to 35 years-old or older.
Let’s explain some of the problems with white pines in the landscape.
The white pine is by nature a brittle, soft-wooded tree. Nature has made older white pines weak because of their tall, straight center trunk. Historically, this characteristic made white pines attractive to early explorers of America who envisioned using this tall, straight trunk for their sailing ships. Unfortunately these trunks are easily pushed to and fro by heavy winds.
Nature is also guilty of giving white pines poor structural resistance to heavy ice or snow load. Engineers know the importance of structural resistance.
The tree has a fairly wide-spreading root system, but no tap root to speak of to anchor the top as it gets older and heavier. Hobby and commercial landscapers probably like to install white pines since they transplant easily, but their lack of an anchoring tap root can become a problem in the pine’s later life.
Here in Virginia, the white pine doesn’t like our heavy clay soil. Clay soil is poorly drained during wet times and shrinks during dry periods. Soil shrinkage can impede root development as well as reduce oxygen available to growing roots.
I personally don’t recommend white pines anymore. As an alternative evergreen, I suggest one of the hybrids of Foster’s hybrid hollies where space is limited and a 25-foot tall, cone-shaped, leafy evergreen is suitable. Otherwise I recommend one of the varieties of the leafy evergreen American holly where a large-growing evergreen is desired.
