Q. We are still in a terrible drought that began this summer. Most of my perennials are drought-tolerant, and have done ok with a weekly slow soaking. But do I continue watering now that it's time for the plants to start going dormant? If so, how much? I'd like the plants to go to sleep; not fall into a coma! Love your show...
- ----Judi in Cincinnati
Now, I'm only talking about 'woody perennials' here; that means plants that have a significant year-round presence above ground, like trees and shrubs. "Herbaceous perennials"—things like spring bulbs, hostas and peonies, whose above ground growth vanishes over the winter—should not be watered after that above ground growth fades for the season. The underground parts of these plants are adapted to going dry when dormant, and kind-hearted watering could rot them.
And if you want to apply a winter mulch around or above new plants to prevent their 'heaving' out of the ground during hot/cold temperature swings, wait until AFTER the soil freezes hard to apply the mulch; don't let any mulch touch the trunk of any woody perennial; and never apply any mulch deeper than two inches.
Q. I have two five-foot-tall potted oleanders that are currently outside. What care do they need over the winter? Do I have to bring them in? Can I leave them outside? What if I plant them in the ground?
- ----Mark, near Philadelphia
As with your oleander, if I left that warm-weather lover outside in its pot here in the North, it would die. If I took it out of its pot and planted it in the ground, it would die. Tropical is tropical, pal! And potted plants in general don't do well over winter in cold climes because their roots don't have any 'below-the-soil' frost protection. So if you have anything outdoors in a pot in the North, you should do something with it.
If the plant is not hardy for your zone (which is fairly easy to look up), it has to come inside. If the plant IS winter hardy (like an apple tree, rose bush or blueberry shrub), it will survive outside if you dig a hole and plant it or dig a hole and drop the pot into the hole so that the lip of the pot is even with or just below the soil line. This is actually preferable to bringing such plants inside, as many hardy perennials have a 'chilling requirement' and need some exposure to cold weather to be productive.
Don't bury terra cotta, ceramic or similar pots; they will shatter over winter, guaranteed. Remove the plants and put them in the ground with as much potting soil still around their roots as possible and store the container indoors in a non-freezing area. Plastic pots can just be dropped into the ground. They may break, but hey—they're plastic. So get over it.
What's that? You say you got no outdoor space to get those roots below ground?
- Nice planning. And:
- You must know somebody with dirt! These plants need no care over the winter, just to be below the soil line. So be creative and borrow some land for a while.
- ----Mike in Easton, MD
Your 'blooms in bondage' fantasy would likely girdle the trunks and kill the trees. And no woody plant should be pruned in the fall; the plants are trying to go dormant, pruning wakes them up, and your 'good intentions' could wind up being deadlier than a five-day ice storm.
If you're going to insist on staring at them all winter with one eye while you keep the other eye focused on the Weather Channel looking for bad news, cut them back by one third when they're fully dormant in January. Or wait until the Spring, when its safest to cut summer-bloomers back. Then prune them every Spring thereafter—and not into a shape that's going to give you shpilkes all winter!