I am in the process of building a home in Northeast PA on my wooded lot (which is why I decided to build there) and want to save as many trees as possible. Aside from locating the house to allow keeping some nice trees, I also had an arborist walk the lot, prune back overhanging and dead branches, and tell me the close ones (mostly white oaks and shagbark hickory within 6 to 10 from the house) should live. Now that the excavation is done, there are some things we could not avoid. Obviously cutting some roots and particularly, piling the excavation dirt around trees temporarily until backfilling is complete. Due to many factors, the construction schedule is taking longer and I’m concerned that these trees may begin to suffocate (It’s been about 6 weeks). In addition to watering them every (2) weeks or so, I read countless articles on preserving trees and one thing suggested is drilling 2” holes in a circular pattern in the trees root zone to allow roots to breath and absorb nutrients. My questions are as follows:

Won’t drilling holes actually hit the roots causing them to be damaged?
If not can a 1” hole be used and how deep?
For the trees covered by the temporary dirt is watering around the trunk sufficient since the root zones are covered?
Should I be watering more often or less?

What else can I do to help these trees survive?

Any response will be appreciated.

Reply to post by Matt M, on July 10, 2002 at 09:38:56:

Yes drilling hurts roots; that's why I use a pick or an AirSpade for aeration.

Move the dirt NOW; forget convenience. Root systems should be mulched 6" with coarse wood chips to lessen compaction. yes water deeply but only 1x/wk. Hickory and oak do not like to stay soggy.

Anyone who says hickories 6' from foundations will survive is very optimistic to put it mildly. They are the most unforgiving genus I work with. See www.isa-arbor.com, Consumer Information about avoiding and treating construction damage

Reply to post by Matt M, on July 10, 2002 at 09:38:56:

There is some information we don't yet have.

How deep is the soil around the trees?
Is it piled against the trunks?
What is the soil type?
How large are the trees? How old?
How large an area does the soil cover around the trees?

If the soil covers a small area, it may be that roots extend well beyond the soil fill. If this is the case, the long transport roots may keep the tree alive, provided you get the soil off the surface soon. And in doing so, avoid further damage or compaction.

For the soil boring, wait until the fill soil is removed. The problem is in the area now covered. Silting and compaction are the most common problems, preventing gas exchange in the soil. Drilling the holes helps to get the air moving below. The holes can be one inch, if that's the equipment you have. Make holes 2 to 3 feet apart, and about 6 to 10 inches deep. Fill with a coarse material such as sand or compost. Only use fertilizer if a soil tests suggests it is needed. The trees will be under stress for a few years, and it may not help them to add fertilizer- it could add to the stress.

Water in areas outside the soil fill, with the hope that there are some roots out there. A deep watering once a week (less if you get some good rain) is better than frequent light watering. The soil should be moist to about 4 to 6 inches deep.

You'll need to watch these trees closely for the next 5 to 10 years. Remember that they will take time to readjust. Don't overdo the treatments. Give the trees time to respond.

Good luck.

Reply to post by Russ Carlson, on July 10, 2002 at 09:38:56:

The soil around the trees is about 2 ft and covers about 60% around the trunk. That is 60% of the entire drip line is covered. The soil is a very clayey soil. The trees in question are a hickory 20" caliper and a some smaller oaks about 10" caliper.