When do I remove my shrub and plant covers? - Ask Extension
I live on a hillside in Hinesburg with brisk winds that tend to create winter wind burn especially on my conifer "Fat Alberts" and others. T...
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When do I remove my shrub and plant covers? #823793
Asked March 29, 2023, 3:33 AM EDT
I live on a hillside in Hinesburg with brisk winds that tend to create winter wind burn especially on my conifer "Fat Alberts" and others. This year, my second happy year BACK in Vermont, I wrapped them last fall and would like some advice on when to remove the coverings. The Farmer's Almanac and such recommended around the last frost. Early May? Mid-Late April? Please advise and UVM is my Alma mater. I'm very happy about THAT. Class of '81 and '82
Sincerely,
Phil A. Gianelli, MD
Chittenden County Vermont
Expert Response
Hi, Phil. Glad to have you back in Vermont!
With a thought to the future, here's a good reference from Wisconsin Horticulture on on avoiding evergreen winter burn: Winter Burn. Recommendations include: don't prune in late summer or fall; mulch properly; water properly; don't fertilize in late summer or fall; and protect during winter.
Thinking about wrapping evergreens (again, looking ahead to next winter), there's very specific advice in the reference above about protection: "Use burlap, canvas, snow fencing or other protective materials to create barriers that will protect plants from winter winds and sun. Install four to five foot tall stakes approximately two feet from the drip lines of plants especially on the south and west sides (or any side exposed to wind) and wrap protective materials around the stakes to create “fenced” barriers. Leave the top open. These barriers will deflect the wind and protect plants from direct exposure to the sun. Remove the barrier material promptly in spring. DO NOT tightly wrap individual plants with burlap as this can collect ice, trap moisture and make plants more susceptible to infection by disease-causing organisms."
The general advice I find is to unwrap "after winter's last frost", but that advice seems very general. A more specific piece of advice is to "continue protection until the temps stay above 28 degrees." Another specific is to unwrap evergreens on a damp, overcast day so the foliage has a chance to acclimatize to the sunlight gradually and avoid scorching. Overall the concern is about cycles of warm sunny days followed by freezing nights causing some damage to bark and buds as they swell in the warmth and then freeze.
I'm not a tree expert, but I would pay attention to the weather and the "temps above 28 degrees" advice. Spring weather varies, so you might be unwrapping in mid-April or late-May depending on the year and your specific location.
I hope this is helpful. Let me know if you have more questions or want to share more specifics to your situation.
With a thought to the future, here's a good reference from Wisconsin Horticulture on on avoiding evergreen winter burn: Winter Burn. Recommendations include: don't prune in late summer or fall; mulch properly; water properly; don't fertilize in late summer or fall; and protect during winter.
Thinking about wrapping evergreens (again, looking ahead to next winter), there's very specific advice in the reference above about protection: "Use burlap, canvas, snow fencing or other protective materials to create barriers that will protect plants from winter winds and sun. Install four to five foot tall stakes approximately two feet from the drip lines of plants especially on the south and west sides (or any side exposed to wind) and wrap protective materials around the stakes to create “fenced” barriers. Leave the top open. These barriers will deflect the wind and protect plants from direct exposure to the sun. Remove the barrier material promptly in spring. DO NOT tightly wrap individual plants with burlap as this can collect ice, trap moisture and make plants more susceptible to infection by disease-causing organisms."
The general advice I find is to unwrap "after winter's last frost", but that advice seems very general. A more specific piece of advice is to "continue protection until the temps stay above 28 degrees." Another specific is to unwrap evergreens on a damp, overcast day so the foliage has a chance to acclimatize to the sunlight gradually and avoid scorching. Overall the concern is about cycles of warm sunny days followed by freezing nights causing some damage to bark and buds as they swell in the warmth and then freeze.
I'm not a tree expert, but I would pay attention to the weather and the "temps above 28 degrees" advice. Spring weather varies, so you might be unwrapping in mid-April or late-May depending on the year and your specific location.
I hope this is helpful. Let me know if you have more questions or want to share more specifics to your situation.
Hi Juanita,
Thank you so much for this comprehensive recommendation! I will surely wait until the weather stabilizes here in Vermont ? ? ? Just joking - late April/early May I'll unwrap slowly and carefully and gently. Last year I only sprayed WiltStop and 1/2 of the pines burned as a result. We'll see. Thanks again for your assistance.
Be well and safe - Phil Gianelli, MD
