Marianne, We get a temperature extremes here all the time with no snow cover and for the most part the perennials survive. Some winters my plants get so confused. Right now a lilac bush is showing the green through its buds but we have been down around 0 several times. We do not often go much below -15C but it doesn't always come with snow cover. If you have mulched the plants should be mostly fine the burying and straw around the pots should help. Heather on Vancouver Island >Hi group, > >For the last couple of weeks we've had some pretty cold temperatures here, >lows of -8 to -12C and highs of -5 to -2C and next to no snow cover. >Everything is frozen solid. Suddenly, starting about a half hour ago, we >are having a sudden switch to very warm temperatures. According to >Environment Canada we could have as much as a week of sunny days with temps >where the highs are +12C and lows of +5C. Ack! Only a gardener would find >this upsetting. ;-) > >Much to my dismay, I've had to overwinter 10 Florentine Iris rhizomes in >pots this year. Earlier in the fall I paritially buried the pots and >covered them with 2 feet of straw which has since packed down to about a >foot. I *don't* want those pots to start thawing! They are my main concern, >the other perennials are probably tough enough to manage with the mulch >they have. I have several green plastic bags of leaves that I've thrown >over top of the area where the irises are. But I'm wondering if the green >plastic will make things worse by transferring heat to the frozen mulch. > >Can anyone offer any experience with sudden weather switches like this one? >Should I be running madly about looking for more straw? > >Marianne >mlepa@adan.kingston.net >Southeastern Ontario AgCan zone 5b >