I have a few acres with established oak trees and other hardwoods. I want to fill in under them with evergreen trees and shrubs, such as white pines, firs, rhododendrons, Japanese maple, hemlock, cedar and spruce trees Question: Will the oak drip line kill them ? Thank You Bill

Greetings Bill!

I do not recommend planting non-native species in the understory of an established forest. Control of non-native species in our native forests costs the state and tax payers millions of dollars on an annual basis because these non-native species tend to spread and takeover our native woodlands.

Only eastern white pine and northern white-cedar, which you mentioned in your question, are native to Illinois. True firs, spruce, hemlock, Japanese maple, and rhododendron are not native and not recommended for introduction into your woodland.

My suggestion, only plant native species in your woodland. For a list of native Illinois woody species, please visit the following URL:

http://www.inhs.uiuc.edu/~kenr/woody.html