When to Plant Crocus
Why does it matter when you plant your bulbs and corms? It would seem that as long as they get in the ground they will grow when it is time, but actually, bulbs, tubers, and corms require certain conditions to break dormancy. The plant will not emerge if it doesn’t get this combination of correct conditions. The best way to achieve this is to plant them just before they will experience those circumstances. Since crocus is considered a spring bloomer, you need to plant corms in late summer to early fall. Crocus requires a minimum of 15 weeks of chilling to break dormancy. The chilling period gives the corm the clue that it is not time to grow up through the soil. This prevents early tender shoots from getting zapped by freezing temperatures. The process is called vernalization, and most plants undergo some form of it during the cold season; however, some plants don’t even need it to sprout. Planting times for crocus differ from other species. Ideally, the best time to plant a crocus corm is six to eight weeks before the first expected frost. This allows the corm to develop a root system before going dormant.
Crocus Bulb Growing
Interestingly, most plants not only need vernalization but also increased photo hours to sprout. Crocus corms will not bloom if the photoperiod is not long enough to provide solar energy. Therefore, planting times for crocus must include this factor in addition to the chilling period. It is not uncommon to see crocus arise from the snow, but without the right amount of sunlight, the plant will fail to bloom. The 15 weeks of chilling will usually take you into March, which is when daylight hours are increasing, and ambient temperatures start to warm. All this signals “bloom” to the plant and points to the best time to plant a crocus.
Crocus Planting Tips
Satisfying the chilling and photo-period requirements are important for crocus bulb growing but so is the actual planting. Choose a sunny location with well-draining soil for crocus bulb growing. This is important to prevent the corms from sitting in a bog and rotting. If the soil has too much clay, amend it with bark, leaf litter, or compost. Sandy soils will require some organic amendment to enhance nutrient content. Select corms that are healthy and free of disease, mold, or damage. Dig trenches 5 inches (13 cm.) deep and plant corms with the flat side down and 1 to 2 inches (2.5-5 cm.) apart. Cover with the soil and wait until spring!
