Q: When you know the temperature is going to be way below freezing one evening and your plants need watering (especially tender perennials), is it better to wait? Or does watering do more harm than good? Is dry soil a better insulator around the tender roots than wet?
A: Hmmmm, that’s a question I haven’t ever been asked. I think I’d tend toward watering them before the cold weather hits so the foliage and stems remain healthy as temperatures drop. My pansy, aucuba and daphne plants looked horribly wilted during the snow and cold of early January but that’s how they protected themselves from the freezing temperatures. Having plenty of water around their roots, they perked right up when temperatures climbed a day later. Had the soil been dry they might not have recovered so well.
Roots of many plants can stand being frozen solid in winter. How else would they garden in the frigid Northeast? All plants have a low temperature limit but some have more cold tolerance than others. Right now I’m growing several different oleanders in my back yard to test the cold-hardiness I’ve been promised they possess. Time will tell if they can survive in Atlanta. Researchers have devised laboratory tests to determine the cold hardiness of plants but they are beyond the skills of ordinary gardeners.