Bulb plants originated in mountainous areas where the climate is temperate and there is a cool period for dormancy. Cultivation of bulb flowers like the tulip comes from the time of the Ottoman Empire and grew in popularity throughout Europe in the middle ages. Growing bulbs is rewarding because the flowers are uniquely beautiful and they are easy to care for.
A bulb is any plant that stores its complete lifecycle in an underground storage structure. Tubers, rhizomes and corms are also underground storage structures and are often confused with bulb plants. Daffodils, tulips, crocus, hyacinth and alliums are true bulbs. The iris grows from rhizomes, gladiolas and lilies from corms. Dahlias are tuberous plants. Planting and growing needs are similar for bulbs, tubers, rhizomes and corms.
Bulb plants are usually perennials that have a period of flowering and a period of dormancy. In dormancy the plant dies back to ground level. The foliage and flower stalks fade to provide energy to the underground bulb as it prepares for next year's growth. The foliage and flowers create the plant's nutrients. Bulbs propagate by growing new bulblets that develop at the base of the bulb.
Bulbs such as tulips and daffodils need 6 to 8 hours of sun per day. Crocus and hyacinth adapt to partial shade. Spring blooming bulbs can be planted under trees that do not grow early spring foliage. All bulbs need very good soil drainage. If the planting site has heavy clay-like soil, it can be improved with the addition or organic compost. Bulbs will produce the best flowers if grown in nutrient-rich composted soil.
Bulbs, tubers, rhizomes and corms that are purchased from a garden center or by mail-order always have the recommended planting depth listed on the package. The planting depth is usually 2 to 3 times the size of the bulb. Tulip and daffodils require an 8-inch planting hole; crocus and hyacinth are planted 3 to 4 inches deep. Smaller bulbs such as anemones are planted only an inch underground. Plant the nose of the bulb upwards with the root-plate down. Iris rhizomes are planted close to the surface.
Water retention will not be a problem when planting has been done using compost to amend the soil. Poor drainage rots bulbs. They are usually watered well immediately after planting but then left dry until the first buds appear. About one inch of water is added weekly as the plants grow, bloom and die back. After the plants bloom and fade, foliage should remain until it turns yellow and dies back naturally. Many gardeners inter-plant bulb sites with annuals to bloom as the bulb foliage fades.