Divide your perennials when ground is dry

Most perennials are best divided in spring, when they are showing a couple inches of growth.

When dividing a plant, choose the strongest looking parts of the plant and discard the rest. A sharp, flat garden spade works best for this job.

Plants that bloom in April and May can also be divided after they bloom.

• The spring has been cool and rainy so far, so plan your garden work to avoid beds that are wet. Working with and walking on soil that is too wet can damage the soil structure. Garden soils generally take longer to dry out in the spring due to the cooler temperatures.

• Install support for perennials that require staking in early spring as they begin to grow. It is best to install support systems before the plants need support and let them grow up through your support system.

• 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 when cutting them back and removing old leaves to avoid damaging new shoots.

Cut perennials, especially ornamental grasses, back higher above ground to help avoid damaging new growth.

• Use an electric hand grinder to sharpen your spades. I prefer to sharpen only the inside edge of the spade. Move the grinder steadily back and forth as you sharpen the spade to avoid too much heat from building up and damaging the metal.

Wear ear and eye protection while doing this work, as it is very noisy and there will be sparks flying off the spade as you work. Keeping the spades sharp will make gardening much easier. New spades do not come with a sharp edge.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.