The Big Sandy Mountaineer -

Tree Questions and Answers for February

• Why do lilacs sometimes bud in February? The very large flower buds on lilacs were formed last summer and they are not going to bloom during winter warm weather periods.

• Will my lilacs survive if it gets cold again? Lilac is a hardy shrub, and will not be affected when the weather drops below freezing.

• Should I water my trees in February and March during warm weather? Watering is next to useless when the soil is frozen or soil temperatures are below 40 to 45 F. Once temperatures get into the 50s and 60s continuously, plants should be watered.

• Why is a 45-degree soil temperature the threshold? The roots of most woody landscape plants don’t begin active growth until soil temperatures are above 45 degrees.

• Why do I need to wait for warmer temperatures? When the ground is frozen, water can’t get into the root zone. Even when the ground isn’t frozen and the water can reach the roots, plants can’t absorb much of it unless they are actively growing.

• Why do many of our conifers become so drought stressed this time of year? Since evergreens retain their leaves, they lose more water than deciduous plants. That’s why watering evergreens in the fall is more critical.

• When does winter freeze damage often occur? Plants are subject to branch, twig, and trunk damage during winter thaws when temperatures remain 60-70°F for one week or more. By January 1st, trees have usually satisfied their chilling requirements and can begin to grow when conditions are favorable. Hence, a thaw period mimics springtime conditions. Water flows back into cells, the tissue deacclimates to cold temperatures and the plant becomes susceptible to freeze damage.

• What causes frost cracking? Dramatic temperature drops i.e. 30°F to -20°F in a very short time. Extreme temperature drops create uneven rapid contraction of the wood causing trees to crack.

• Do frost cracks affect the health of the tree? Frost cracks apparently cause no long-term detrimental effects to the tree. Trees usually heal the cracks rapidly. Once cracked, trees will likely crack again along the same line in similar situations.

Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.