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Friday - December 09, 2005

From: Auburn, IN
Region: Midwest
Topic: Trees
Title: Determining distance of trees from paving in NE Indiana
Answered by: Nan Hampton and Joe Marcus


I'd like to plant 3 types of trees (Catalpa speciosa- Northern Catalpa; Juglans cinerea - Tulip Tree; and Acer saccharum - Sugar Maple) next to sidewalks and driveways, but need to know if they have roots deep enough to not break up the concrete/asphalt. I live in NE Indiana. Thank you.


Although trees are generally divided into two groups by root type—tap root trees (such as oaks, hickory, walnut, conifers) and lateral, or fibrous, root trees (maples, ash, cottonwood)—this distinction is most evident as seedlings or saplings. Once the tree is planted and begins to mature, the distinctions between the root types become less pronounced. Then, the depth and lateralness of the roots is greatly dependent on the soil condition. Highly compacted soils, soils with low oxygen content and soils where the water table is near the surface are not likely to produce a strong tap root. Their roots are more likely to be lateral and located very near the surface with the majority of the roots located in the top 12 inches of soil. Also, it is important to realize that the spread of the roots can be at least 2 to 4 times greater than the drip line of the branches.

Sidewalks and Trees from Iowa State University Extension Service recommends basing the distance trees are planted near pavement on the mature height of the tree. Their recommendations are:

1. trees with a mature height of less than 30 feet, 3-4 feet from pavement,
2. trees with a mature height of 30 to 50 feet, 5-6 feet from pavement,
3. trees with a mature height of greater than 50 feet, at least 8 feet from pavement.

They also recommend installing root barriers underground between the tree and the sidewalk. Another recommendation from Iowa State is to avoid planting shallow-rooted trees near sidewalks. Unfortunately, the sugar maple (Acer saccharum) is on their shallow-rooted tree list. I am not sure whether you mean to plant the tulip tree, which is Liriodendron tulipifera, or the butternut, which is Juglans cinerea. If it is Liriodendron tulipifera, then that is also on the shallow-rooted tree iist. The butternut, Juglans cinerea, is not on the list, nor is the northern catalpa (Catalpa speciosa). You can read a list of recommended Trees for Parking Lots and Paved Areas from Virginia Cooperative Extension. Be aware that not all the trees on the list are native. The Lady Bird Johnson Wildflower Center recommends that you plant native trees. You can also read more about Tree Roots from Iowa State University Forestry Service.

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