Especially with evergreens, wet snow can weigh down branches and either break or deform them. I don't cover them regardless since I don't like the look.

Sometimes shrubs are covered for cold protection as well. Shrubs that set flower buds early (like fall) can often have those buds damaged by winter cold. Hydrangea macrophylla is just such a shrub - root hardy to least zone 6, its flower buds are easily damaged by excessive winter cold and that's why this shrub is often wrapped or covered in winter.

Broadleaved evergreens are also sometimes wrapped to limit dessication and leaf burn from cold, which the plants can experience regardless of hardiness. And of course, lots of folks will wrap plants that are of marginal hardiness or somewhat newly planted, just to give them an edge over winter cold.

Oh, ok. Thank you so much, both of you, for responding. I know my shrub is hardy to my zone, and well just plain hardy, but maybe I'll wrap it too, since it was just planted a month ago.

Thanks again for your time...

Wrapping - which is best done so it does not actually touch the plant - does little to modify temperature. What it does do is protect plants - especially evergreens - from the drying effects of sun and wind which can severely damage even very hardy plants. When the soil is frozen a plant cannot draw up moisture through its roots. This can lead to dessication, especially on the side most exposed to sun and wind.

Wrapping or other forms of protection can also prevent rapid flucuations in temperature which can be just as damaging as cold. Some shrubs - daphne is a notorious example - also need to be protected from the weight of snow which can split the wood.

For non-evergreens, mulching well is probably the best thing you can do to protect new plantings for the winter although there are some such as magnolias and Japanese maples which will also benefit from having their bark shielded from winter sun. For marginally hardy plants, a teepee style burlap barrier can provide just the few degrees difference between serious damage and little to no damage.

ilovemytrees - if you are referring to your Forsythia, I doubt it needs wrapping. But others in your zone might be able to advise more knowledgeably.

Broadleaved evergreens are also sometimes wrapped to limit dessication and leaf burn from cold

==>> let me expand on what gal said ...

lets pretend z5 is minus 20 min winter temp.. [i am not looking it up this morn] ... so a z5 plant should handle that no prob ...

however.. add a 30 mile an hour wind ... and you have it a lot colder on leaf surface .. due to wind chill.. which technically does not change the base temp ... its still z5 ...

so not unlike wind burn on your skin .. you can get wind burn on leaves ...

so on my rhodies ... which is just about the only evergreen, non conifer i have ... i used to put up wind screening ... [though on some foo foo tiny VERY YOUNG conifers.. i have been known to use old Styrofoam rose cones ...]

and.. its all about root mass .. and the plants ability to go into winter .. turgid.. or full of water.. w/o its roots frozen into an ice cube ... BEFORE THE GROUND FREEZES ... and on that.. its ability to cope with leaf desiccation ...

this is probably a BIG ISSUE in ground freeze areas ... as a plants roots are in suspended animation.. and can add nothing to the leaves in winter ... i would presume in non-ground freeze areas.. it would be much less an issue .. though the potential would be there ......

BUT!!! .. i used to do all the snow load worrying.. i say pshaw on that now.. if it breaks.. it was inherently weak in form.. and now.. i tend to just repair the breakage in spring.. and try to prune to a better form which can cope.. of course.. sometimes i lose in that ...

but after a few years.. i dont even worry about the wind.. a very established.. proper zone plant.. should be able to cope.. as i say.. they arent my children.. at some point they.. like the children.. have to grow up and cope..

ken

ps: you didnt ask about multi leader arbs.. so i am not wasting time on that ... but they should ONLY be wrapped to fend off deer.. but they can be TIED .. etc.. blah.. blah. blah ...

hey!!!

did any of that make sense.

one other cliche i have.. is to think of old chicken in the freezer .. the tissue freeze dries ... that white stuff on the meat ...

that is basically what happens to a leaf ... all the moisture is pulled out of the product ... which is what freeze dried is all about .... ergo.. it scars and browns.. once the weather starts to warm in spring ... [the leaf.. not the chicken]

also.. to clarify ... with the 30 mph winds.. the roots are still in z5 ... wind chill does not affect ground temp ... and though wind chill may affect the leaves.. and that above .. the roots wont necessarily die ... so many shrubs can re-sprout from the ground [or snow cover .. etc] in the worst circumstances.. presuming the roots are true to form .. not grafted ....

roots usually die due to repeated freeze thaw cycles ... which is back to the other cliche.. get them dormant.. keep them dormant .... which is what your mulch helps avoid ... black soil in winter sun thawing in warm spells ...

ken

Where I live we don't usually get bad freezes. My house faces south, and sometimes I have the same things planted in both front and back yards. When we get a norther with below freezing temps, sometimes I lose plants in the back yard, while plants in the front aren't damaged. That cold wind can do damage that cold alone doesn't do. Covering plants will protect them from that frost damage. Don't use plastic, though.

So called "wind chill" may not effect plants in the same way it effects people, but it definitely does effect ground temperature indirectly. It accelerates the rate at which the ground gives up its heat, thereby contributing to the depth of frost penetration. Mulch or other forms of ground insulation slow the rate of heat loss even in windy sites.

and the box, burlap or rose cone protection .. is a VERTICAL mulch ... keeping the sun off the soil immediately near the plant

ken

I'm thinking this is a trick question.

Cuz who likes an exposed bush?

time to pop the top and enjoy a brew