Q: As you can see from the attached photo, tree roots are surfacing in the lawn, which makes mowing difficult to impossible. Do you have any suggestions? I鈥檓 not sure if we should cover them and build up the ground around them? Will the trees die if we just leave them? Thanks for any light you can shed. 鈥� Lavonne L.
A: Thanks for asking a common question. Tree roots are supposed to stay in the ground, right? Well, that鈥檚 not always the case in nature. A walk through a heavy forest quickly teaches us to watch our footing, as large horizontal roots protruding above ground are natural.
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Tree roots are much shallower than we often imagine, with most of a tree鈥檚 root system contained in the upper 1 to 2 feet of soil and spreading outward. As trees age and roots thicken, it鈥檚 natural for parts of larger roots to extend above the surface, with some tree species being more inclined to develop surface roots than others.
Removing these surface roots is not recommended by tree researches at universities like Cornell and New Mexico State University. Removing roots can weaken a tree鈥檚 support, create open wounds where root rotting organisms can enter and cause decline in upper branches.
One option is to leave the roots alone, since there鈥檚 nothing unnatural about the roots. Or you can fill in around the roots with no more than 1 to 2 inches of high-quality, non-heavy topsoil. Adding a too-deep soil layer can cause tree decline. In some situations, mulching around the entire tree with 2 inches of shredded bark will fill the spaces between roots and eliminate the need to mow.
Q: Can you direct me to a local nursery that carries the perennial hibiscus? 鈥� Kathleen H.
A: Perennial hibiscus is a beautiful flower that is winter-hardy in most of zone 4. The huge flowers are extremely showy, and this perennial is sure to turn heads.
The best place to find it will probably be locally owned garden centers. Perennial hibiscus is becoming more popular and more widely available, especially with the introduction by Proven Winners branded plants of the Summerific series, and introductions from other plant breeders.
Perennial hibiscus should be planted in a somewhat sheltered location in full sun or light shade, rather than in an exposed, hot, windswept spot. Consistent moisture is critical, and a mulch layer of shredded bark will help greatly.
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In areas closer to zone 3, adding a winter protective mulch in November will improve survival. New growth of perennial hibiscus emerges from below ground each spring, rather than last year鈥檚 stems.
Q: This is my first year planting potatoes. I bought certified seed potatoes from a garden center. Some of the potatoes are large, and some are small. I know you cut up the larger ones, but with the smaller potatoes, do you cut them, or plant the whole thing? 鈥� Sam L.
A: Starting with certified seed potatoes is an important step in getting a good crop of disease-free potatoes. Tubers the size of an egg or slightly smaller can be planted whole, without cutting them.
If tubers are larger than an egg, cutting is customary. Cut the tubers into chunks so each piece contains at least two 鈥渆yes,鈥� which are the depressions from which the sprouts arise. Plant with the eyes facing upward.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.
