Crocuses grow in rock gardens and beneath shady trees

Crocuses are ideal bulbs for naturalizing, for rock gardens or for underplanting beneath tall trees. They may be scattered in lawns, but their grasslike foliage must remain intact for at least six weeks before being mowed to a short height for long-term best results.

Crocuses, which are planted shallowly, are easy targets for chipmunks and squirrels. They might require repellent products or light chicken wire screen placed directly over them at planting time. Blood meal sprinkled on the ground after planting may help repel squirrels and chipmunks.

• After a killing frost, remove dead plant debris from annual and vegetable beds.

Sanitation is especially important if you have had disease problems in your planting beds. Remove all diseased foliage or fruits and do not add affected materials to your compost pile, because most home compost piles do not get hot enough to kill disease organisms.

• It is best to stay off the lawn when there has been a frost. Frost on the grass indicates water inside the leaves is frozen, so traffic on the turf can cause the frozen water in the cells to rupture, which kills or severely stunts the leaf blades.

The symptoms generally appear purplish to black at first, and then progress to a straw color. When frost is heavy, the cell disruption can occur at the crown and kill the entire plant. If there is no damage to the crowns, the turf will recover from the generation of new leaves.

Once everything is frozen, it is less of an issue, as the solidity prevents the cells from rupturing.

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