Get digging now for a colorful spring surprise

Spring-flowering bulbs can add a lot of interest to a garden. When you buy bulbs in a garden center, choose those that are plump and firm with no mushy spots. Small nicks, loose tunics or blue/gray mold do not affect the development and health of bulbs.

Bulbs with white mold or that are soft and lightweight with a strong moldy smell are probably not good. If your bulbs cannot be planted right away, store them in a well-ventilated area that is cool but above freezing, out of reach of rodents and away from ethylene-producing materials such as ripening fruit. Artificial heat will dry bulbs, while high temperatures may destroy next spring’s flower in the bulb.

Most bulbs should be planted after a hard frost beginning in mid- to late October and before the ground freezes. Fall-flowering bulbs such as autumn crocus (Colchicum) should have been planted as soon as they arrived in early to mid-September.

Bulbs rarely look good alone or in rows. Plant them in clumps or drifts. Bulbs such as daffodils and glory of the snow can be naturalized or planted to look as if they are growing wild. One way to do this is to toss handfuls of bulbs and plant them where they land.

Small bulbs such as crocus should be planted in large groups of at least 30 to 50 so they are more prominent in the landscape. Incorporate bulbs into the perennial border in groups of seven to 15 bulbs or more.

Consider how you are going to manage bulb foliage when planting in perennial borders, since the bulbs need to go dormant before you cut back the foliage. Lots of browning bulb foliage can be intrusive in a perennial border, so choose ones with less foliage or blend carefully with larger perennials.

If you are planting bulbs for next spring, keep in mind that daffodils are among the hardiest, most adaptable and pest-resistant bulbs for Chicago-area gardeners. They naturalize beautifully and are available in many sizes and bloom times. Proper selection of varieties will give three to five weeks of constant bloom. Deer, squirrels, chipmunks and rabbits do not eat them. Ornamental onions also will not be eaten by animals.

Tulips are favorites for deer and rabbits to eat. Deer were digging up tulips to eat them as they were sprouting underground in several Glencoe gardens this past spring. In my garden, squirrels and chipmunks leave winter aconite and snowdrops alone while eating all the crocus.

Proper placement is important for success with spring-flowering bulbs. They prefer moisture in early spring and fall and to be dry in the summer when they are dormant. They do not like wet sites or heavy clay soil. If your soil is on the heavy side with a high clay content, plant bulbs higher than normally recommended. In general, plant bulbs at three times the diameter of the bulb. Also, consider the color of plants that will be flowering adjacent to the bulbs you are planting to avoid color clashes next spring.

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