Crocus are some of the most popular spring-blooming flowers—and with good reason. These cheerful flowers are some of the first to bloom in early spring and provide welcome pops of color. Available in an array of colors, including white, purple and yellow, crocus bulbs can be planted in flower beds, rock gardens and containers. For an impressive look, plant hundreds of bulbs in drifts in grassy areas, woodlands and under trees. Most crocus grow 4-6 inches tall, and like other flower bulbs, perform best when planted in well-drained soil. Crocus look best planted in groups of 10 or more, and they naturalize well. They grow in zones 3-9.