The garden is finally done showing off for the season. We skipped frost entirely this fall and jumped into a hard freeze instead. The low temperature the other night dipped to 24 degrees. Interestingly, even after the freeze some of my I’m-going-to-live-forever ‘Opera Supreme Pink Morn’ petunias are STILL alive and blooming. At this rate, they’ll be sticking out through the snow in December.
When the nighttime temperatures start dipping below 20 degrees or the snowflakes are flying, it’s tempting to cover your roses and other less hardy perennials. Resist the urge. I was surprised to learn in my Master Gardener class that the reason you cover plants for the winter is to keep them cold not warm. You want them to remain dormant until spring. If you cover plants too early they may send up new growth which will get nipped off when temperatures take a dive. Repeated freezing and thawing weakens plants and makes it less likely that they’ll survive winter.
You should wait until the ground freezes before putting straw or leaves or even rose cones over your plants. In southern Wisconsin, the rule of thumb is to wait until Thanksgiving. This year it will probably be December before the ground is frozen and it’s safe to tuck your plants in for the winter.