You will need to prevent the crowns, tubers and roots of your aquatic plants from freezing. While hardy water lilies and lotus can be moved to the deeper end of the pond (about two feet down), more tender specimens must be removed before the first frost. Lift plants, cut back any old, yellowing leaves and store in containers of damp sand in a cool, dark space (down to +5°C is ideal). To keep air flowing and plants damp, cover containers with a perforated plastic sheet. Tropicals like umbrella palm, papyrus and white arum lilies will continue to grow by a sunny window if kept just moist.
Bring in any container herbs, like basil or sage to keep them in active growth in a bright, south-facing window over the winter. Keep the soil just moist. They’ll continue to grow, but at a slower rate than in the summer due to winter’s lower light levels.
Herbaceous and woody perennials that need a period of dormancy—like heuchera and tender roses—can be stored in a dark part of the basement or garage against the warmest wall. After the first frost, water plants well, dig up and pot. Cut away old foliage and prune back woody perennials once the leaves drop. Keep the soil just moist all winter.
“In warmer zones, plants may only experience a period of reduced growth, rather than true dormancy,” says Reid, who is also a landscape design instructor at Ryerson University’s Chang School. “This requires lower light levels and less water.” Ti tree (Cordyline fruticosa), passionflower and mandevilla, for example, should all be acclimatized before being moved indoors or the stress could cause leaf drop. Place the potted-up plants into a shady part of the garden for a few weeks before the big push indoors.