Spring is best time to divide your perennials
Most perennials are best divided in spring when they are showing a couple inches of growth.
A sharp, flat garden spade works best for this job. When dividing a plant, choose the strongest-looking parts of the plant and discard the rest. Plants that bloom in April and May also can be divided after they bloom.
Install supports for tall or floppy perennials in early spring as they begin to grow. It is best to install the support, such as stakes or a wire hoop or grid, before the plants actually need it and let them grow up through it.
If you are running late getting your garden cleaned up, it is OK to continue removing garden debris from beds and cutting back perennials.
The perennials will have begun growing, so be very careful not to damage the new shoots when cutting the dried stems and leaves back and removing debris. Protect the new growth on perennials, especially ornamental grasses, by cutting them higher than you would if you were cutting them back in the winter.
Keeping the spades sharp will make gardening much easier. New spades do not come with a sharp edge.
To keep your spades sharp, use an electric hand grinder. Wear ear and eye protection, as this is very noisy work and sparks will fly. I prefer to sharpen only the inside edge. Move the grinder steadily back and forth along the spade's edge so excess heat does not build up and damage the metal.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.