Will exposed roots damage plants?
On frosty mornings, some of the plants I put in last fall seem to be lifted out of the ground, with their roots exposed. Will this damage them? — H.B., Rockport, ME
Fluctuating temperatures that thaw the soil during the day and freeze it at night can cause the “frost heaving” you describe. This tends to be a problem with newly installed plants that have not yet sufficiently rooted, especially where the bare ground is exposed to the winter sun. Frost heaving tends to occur in early spring and early winter. If enough of a plant’s roots are exposed and dry out, the plant may be damaged.
There are two solutions to this problem: Either press the plants firmly back into the ground when it thaws, or add fresh soil to cover the exposed roots. Then, after the ground freezes again, apply a layer of salt-marsh hay, pine needles, or leaves as mulch. Mulching covers the bare soil, shades the ground, and helps keep the area around the roots frozen, preventing the freeze-thaw cycle that causes heaving. If you add new soil to cover, remember to press the roots into the ground in spring when the ground thaws, and spread out the excess soil.
Please don’t make the mistake of installing your plants too deep — roots must not suffocate, and the area where the roots flare from the stems should be close to the surface of the soil.
–R. Wayne Mezitt, Chairman, Weston Nurseries, Hopkinton, Massachusetts