Many folks are hesitant to plant perennials and other frost hardy trees and shrubs before the last average frost date of the spring. “What if it freezes”? “The cold weather will kill my new plants.” And so on. But the bottom line is that many perennial plants (as well as trees, shrubs and evergreens) prefer to be planted in the cool of spring. I start planting as soon as the soil thaws in March here in zone 6 Santa Fe. Here in northern New Mexico, like most of the Great Plains and Intermountain West can get snow clear through May. So here are my thoughts on why not to wait.
Frost hardy plants love to get an early start and shrug off frosts. Occasionally there will be a really hard frost after I plant (temperatures drop into the low 20’s or teens). If I remember I’ll cover the plants for the night with some loose straw or a plastic bag. If I don’t, they may get their flowers or foliage nipped by the cold, but they outgrow the frosted parts quickly.
In fact, I always admonish gardeners to plant before a snow storm if they can time it right. Or I just thank my luck that I happened to plant before a nice snow. But nothing beats new transplants covered by a blanket of snow. Snow protects the plants from the first clear, cold night after the storm with its insulating properties. When the snow melts, it waters the transplants and settles the soil gently around the roots. And snow melt, like rain, has near magically properties when it comes to growing plants. Generally it’s the gentle boast of atmospheric Nitrogen that the snowflakes absorb as they fall from the clouds. I also hypothesize their negative ions have a positive effect on the soil and plants.
When you’re at the nursery, be sure to ask if the plants have been cold hardened. We grow our perennials cold and let them wake up slowly in our high desert cold. You don’t want to take plants straight out of a warm greenhouse into the cold and plant them without acclimating (“hardening”) the leaves and stems to the cold temperatures.
So next time you look out the kitchen window and see your new Salvia covered with snow, smile and thank the clouds for the gift of frozen water.