When temps are consistently above freezing or when you see the first bulbs dive up under the snow, etc-

Dax

first .. do NOT cook them ... instead of focusing on cold.. think about heat build up inside the cone ....

then.. burn is a function of wind.. winter sun .. and then cold...

so the short answer.. there isnt one .... lol ...

its all about your microclimate ... when temps start moderating .. etc ...

you should be past winter minimum colds .... winds ought to be warming .... etc ...

i hate to even give you a guess .... i think you are going to have to intuit the situation ....

but if they are zone appropriate ... i should think you are within 30 days of it being mild enough to open them up ...

now.. all that said.. you did NOT tell us what you are dealing with.. nor why you thought they all had to be covered .... and why.. if they are small .. why you just didnt let the snow cover them???

so more facts might help define the answer ...

and ... are they in darkness completely.. because you might have to take hardening off to sun as a variable also ...

ken

Ken, it's not that difficult. Styrofoam breathes well in cold and heat. It's a great way to send a boxfull of plants during the bleak of 90-100F summer temps.

Cindi, this isn't rocket science. You'll know when it's time. Same for your burlapped plants.

Dax

dax??????

breathable Styrofoam???

if fully enclosed.. in full sunshine.. and ambient temps increase .... then the little Styrofoam greenhouse can get to extreme temps ... [as compared to uncovered] .. and then it falls back to zero that night ... and the roots still fully frozen ... then damage can occur .. sort of akin to bark scald ...

are you suggesting that a little breathing will solve the issue???

when i used such.. the cones had no tops ... so the plants were shaded ... and out of the wind ... but fully able to enjoy/'cope with' the swings of the temps ...

if they are fully covered.. they need to be removed before the ambient temps get too high ...

who really knows when that is ...

same with the burlap ... if its just surrounds a plant.. it can probably stay there all year... but if it fully covers ... then heat build up has to come into the equation ...

i cant recall when i removed mine way back when .... about mid march seems right.. but as my knowledge of zone appropriate conifers grew.. i learned they just didnt need the protection .... and quit bothering with it all ... and ergo.. avoided the issue in its entirety ...

i wonder.. if it is akin to your greenhouse dax .... at some point... you had to start opening the windows during the day .... to release heat build up .... though you closed them at night .... why wouldnt there be the same logic with conally enclosed ... [new word.. lol]

ken

Just take them off late March and be done with it.

Dax

if you just give them the fish, dax..

then they will never learn to fish!!!

you give your pronouncement..

i am trying to teach them the variables for next year ...

you didnt like my analogy to your greenhouse????

ken

So Cindi, what kind of conifers are we talking about? And were they planted last fall or last spring? I'm 100 miles south of you and I've never covered a new conifer for winter. I recall a first year Abies procera not making it, otherwise all have done fine. Like Ken, I too would fear heat buildup before sunburn. I'd lift the cones up off the ground now so air can move through them and remove them completely during a cloudy stretch in about two weeks.

tj

I finally got a chance to see what everyone wrote. I was out sick for awhile. You guys are a hoot you know. :)
Anyway, The conifers are small...some are picea abies, picea orientalis, picea omorika, picea glauca. Lots of other odds and ends in there. Most were planted over the spring to early fall. I'm worried more about burn than I am about survival actually. I also punched some pretty big holes in the styrofoam for circulation.

Cindi
Any thoughts on the burn problem in late winter/early spring? Maybe I shouldn't be concerned about that?

I wouldn't worry about Picea abies or glauca at all. They're pretty much tough as nails. Orientalis ('Skylands') or omorika ('Pimoko') may have some sun sensative cultivars but most of those are tough as well. I'd worry more about rabbits with those. Burn can also be as much (or more) about wind as it is about sun in late winter so that may factor into your concern level, but over all, it may be much ado about nothing with those species.

tj

It doesn't seem any different to me to have a rose cone over a woody stem plant than for it to have been smothered in deciduous tree leaves...the prior fall. I've never used rose cones so I really can't be of much help. My instinct is to remove them early while the weather is still cold but also while it's in the 35F range for as we can all agree about, two weeks or more. Waiting for a long time isn't a good idea... Now Ill admit that when it warms up here (zone 5a IL) and temps become into the exact 40F degree days where it also warms up - more than that, greenhouse doors are kept open all day but are then closed for the night -etc. That's kinda where I started here - the whole temps idea. If anyone is growing a Picea orientalis 'Skyland's' or a Picea abies 'Aurea Jakobsen' they 'will' need to use a shade screen for several years - especially at summer.

Dax

Thanks Everyone for all your educated responses. Gives me much to think about. I think towards the end of March I'll start taking them off and see what happens. I planted 32 of them last year. A lot of the bigger ones I just fenced as the entire rabbit population of WI is in my backyard..:) Sure am looking forward to Spring.

Take care everyone, Cindi