It happens to every gardener at least once--digging through seeds and equipment in early spring only to find a package of tulip bulbs or a stray bag of grape hyacinth (Muscari sp.) that escaped fall planting. Often nurseries place a tempting clearance rack of allium, dahlia and other summer-blooming bulbs under your nose after their planting season has passed. Although may bulbs do not bloom without a cold period, plant them late and reap rewards in following seasons.
Feel the bulb. Very light, mushy or moldy bulbs are not likely to survive. If the bulb still feels firm and plump, plant it outdoors or force it indoors. Do not save bulbs for the following season; bulbs are living plants, not seeds, and grow with or without being planted. When in doubt, plant.
Plant the healthy bulbs outdoors as soon as possible. Plant spring-flowering bulbs in winter whenever the soil is workable to provide the chilling period they need to bloom. Tulips, for example, require weeks of cold temperatures and do not bloom otherwise. If a late-planted tulip doesn't receive a winter chill period, it only produces foliage in the spring; however, the plant returns to bloom the following year, especially if it is a species or botanical tulip. Summer blooming plants planted in winter or fall also put out roots for a jump on springtime growth. Although these late-planted bulbs may have smaller flowers, if they flower at all, they store up energy for the next season's bloom.
Force bulbs indoors if outdoor planting is not an option. Tricking summer-blooming bulbs into flowering is not easy, according to the International Bulb Centre, but the bulbs grow if light and temperatures are right. For spring-blooming bulbs that need winter chill, pot up the bulbs in a damp, lightly-textured planting medium, and store in the refrigerator, shed or cool garage for 12 to 14 weeks. When the bulbs begin to send out roots or green stems, remove them from storage. Place in a sunny location and keep the soil slightly moist.
Trim the finished blooms, and allow the foliage to yellow naturally. Do not over water because this encourages rot or disease on the bulb. Once the foliage has matured, plant the bulbs outdoors. Rather than lifting and separating the bulbs, simply set the bulbs as a cluster and preserve as many roots as possible. Mulch well, and your bulbs may return the following year.