Knowledgebase

Grind a stump out or cover with soil? #415856

Asked July 21, 2017, 11:58 AM EDT

I've got nine fir trees that I would like to take down. Originally planted on the property line about 8 ft apart I thinned them out years ago so there are gaps now from 8 to 24 ft. The firs are at least 60 years old and one fir is obviously dying while the others are beginning to look like the dying one did two or three years ago. They've been a great screen for the thirty years we lived in our house. I definitely have to take the one down and I think it would be cheaper and easier to landscape if I take them all down at once instead of waiting for the inevitable. Instead of grinding out the stumps, I would like to cover the stumps with 1 to 3 ft of black dirt creating a berm or berms. I would then plant one or two new firs, a crab, and Japanese lilac on the berms. Planting on top of the berm would provide an extra one to three feet of height helping to screen our neighbor's yard. The current garden under and in front of the firs is great for shade plants (we are on the North side of the firs). But that area has grown extensively and we would like to have more sun, especially in the winter. That's the background. What do you see as the problems with leaving the stumps in? Should I avoid planting directly on top of a stump? When is the best time to plant trees? How wide should the berm be for trees that would grow to 30 ft tall? Should I cut and shape the berms in the Fall and plant the trees in the Spring? Or can I do all of this starting this August? Thanks Mike

Hennepin County Minnesota

Expert Response

When replacing a diseased tree, use a variety that is resistant to the disease that killed its predecessor. Some diseases persist in the soil for decades. This site will help you determine what disease is killing your trees. http://www.extension.umn.edu/garden/diagnose/plant/evergreen/fir/

There are several fungi that attack fir trees. Design your berm so the trees have great air circulation.

Select a crab apple tree that is resistant to apple scab and fire blight. You can find resistant varieties at this site:https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/managing-apple-scab/

http://www.extension.iastate.edu/article/yard-and-garden-handling-issues-crabapple-trees

Adding extra even a few inches of soil over existing tree roots will eventually kill your trees.

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/environmental/girdling.aspx

The new tree can be planted as close as 6 to 8 feet from the old trunk. Once a tree is removed, its stump may be ground out, pulled, or left alone. Mushrooms will commonly grow around an old dead tree stump, even if the stump was ground out. Nitrogen fertilizer can be added to the soil to make it break it down sooner. http://web.extension.illinois.edu/fmpt/ec/140621.html

http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/removing-trees-and-shrubs/

There really is not an ideal berm width that is best for tree plant growth. The tree's roots will naturally spread far beyond the berm. It will look odd when the tree became really big and dwarfed the berm. And from a maintenance perspective, mowing the grass underneath an evergreen once it's branches grow beyond the bed, is a headache. For these reasons, it's most common to see smaller ornamental cultivars used in berms since they are more in scale with the size of a typical berm. Create a berm that is large enough to accommodate the plant's mature width. If you wanted to use a White or Concolor Fir (Abies concolor) which has a mature width of approximately 15 to 25 feet, then the berm would need to be that width. Firs

Try to determine what disease is killing the existing firs.

http://www.extension.umn.edu/garden/landscaping/implement/soil_berms.html

http://agrilife.org/etg/2014/12/22/solving-wind-sound-visual-problems-with-plants/

Evergreens should be planted in spring, summer or early fall. While deciduous plants can be planted later in fall, evergreens benefit from having some time while the soil is relatively warm to start to become established. If evergreens are planted too late in fall, they will not be well-hydrated and may "burn" or brown during winter. This is due to moisture loss from foliage that cannot be replaced by the roots. Keep evergreens properly watered throughout the growing season and into the fall is another way to reduce winter burn.http://www3.extension.umn.edu/county/stearns/county-horticulture-educator/article/what-happened-my-evergreens

Pat M MN master gardener and TCA Replied July 21, 2017, 2:40 PM EDT

Grind a stump out or cover with soil? #415856

Expert Response

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