A dazzling display of spring flowering bulbs is one of the most welcomed sights after a long drab winter. But the show begins well before the warm days of April and May. Late September through October is prime planting time for spring-flowering bulbs such as crocus, tulips and daffodils.
Spring flowering bulbs are planted in the fall for two reasons. First, they must develop roots to support the new growth. Second, they must accumulate a certain number of "chilling hours" in order to bloom next season. If something should delay your efforts this fall, do not worry. I have planted bulbs as late as January and they have bloomed nicely the following spring.
When planting bulbs, choose a site that has full sun to partial shade. Avoid planting in areas that receive less than six hours of direct sun. The more sun the plants receive, the earlier they will bloom and the stronger and healthier the stems will grow.
Ideally, the soil should be loose and well drained. However, poor soils can be used if organic materials are added. For example, heavy clay soils can be amended by mixing in compost, aged manure, bark mulch or peat moss. Try to give the bulbs a foot of prepared soil with one-third of this being the soil amendments. For example, one-third organic matter means four inches of "good stuff" should be mixed into the top eight inches of soil. Finish by incorporating one pound of 10-10-10 or 13-13-13 fertilizer per 100 square feet. The soil pH should be between 6.0 to 7.0.
Planting depths vary depending on the size of the bulbs. Tulips and hyacinths should be planted about six inches deep and daffodils eight inches. Smaller bulbs are planted shallower. As a general rule: Bulbs should be planted two to three times as deep as their width. Planting depth is measured from the bottom of the planting hole to the top of the soil. Large bulbs should be spaced four to six inches apart and small bulbs about one to two inches. Planting in clumps or irregular masses produce a impressive display than straight rows or single plants scattered throughout the landscape.
After placing the bulbs at the proper depth, replace half of the soil and water to settle the fill. Add the remaining soil and water again. Although there will be no top growth this fall, the roots will develop so the soil needs to be kept moist but not wet. Mulch can be added after the soil has frozen to prevent small bulbs from being removed from the ground by alternate freezing and thawing.
Finally, many times we get into the warm days of February and March and bulbs start to poke their heads out of the ground a bit too early. It is best to do nothing as the bulbs are tough and know when it is time to bloom. Often gardeners feel they need to add mulch to protect the emerging vegetation. This leads to more growth of the plant and more problems.