Ranunculus, commonly known as Persian Buttercups, produce brilliantly colored, rose-like blooms in the spring garden. Although often grouped with true bulbs, these plants grow from corms, which are solid, swollen stems that store food. The unusual, shriveled appearance of the dormant ranunculus corm frequently causes confusion when determining the correct orientation for planting. Understanding the corm’s anatomy and preparation is essential for a successful display.
Preparing Ranunculus Corms for Planting
The dried ranunculus corm is dormant and highly shriveled, requiring rehydration before planting. This preparation is necessary because the corm must be plump and fully hydrated for efficient germination. Without this step, the corm may rot before it absorbs enough moisture to begin growth.
To rehydrate them, soak the corms in room-temperature water for three to four hours. Changing the water hourly is recommended to ensure oxygen saturation and prevent potential mold growth. Avoid soaking the corms for longer than four hours, as excessive moisture can lead to rot. During soaking, the corms will absorb water, softening and plumping up to approximately one and a half to two times their original size.
Identifying and Orienting the Claws
Correctly identifying the top and bottom of the corm is the most important step for successful growth. The dormant ranunculus corm has a distinct appearance, often described as resembling a small octopus or cluster of claws. Recognizing the two different ends of this structure is key.
The pointed, finger-like projections, often called “claws,” are the part from which the roots will emerge. These projections must always be positioned pointing downward into the soil. The opposite end is typically flatter or slightly bumpy and is referred to as the crown. The crown is the plant’s growth point, and the stem and foliage will emerge from it, meaning this part must face upward toward the sky. While planting the corm upside down may not prevent growth, it will delay flowering and stress the plant.
Optimal Timing and Planting Depth
The best time to plant ranunculus corms depends on the local climate, as these plants thrive in cool temperatures and cannot tolerate hard freezes. In regions with mild winters (USDA Zones 8 to 10), planting occurs in the fall (October to December) for earlier blooms. Gardeners in colder areas (Zones 4 to 7) should wait until late winter or very early spring, planting the corms approximately four weeks before the last expected frost. This timing prevents the corms from being exposed to freezing temperatures below 25°F, which would cause them to rot.
Ranunculus requires a location that receives full sun and has rich, well-drained soil. Set the corms about one to two inches deep in the soil. Planting too deeply increases the risk of rot, especially in heavy soil. Space the corms approximately four to six inches apart to allow for good air circulation, which helps prevent disease.
Initial Care After Planting
Once the corms are placed in the ground with the claws facing down, water the area gently but thoroughly. This initial soaking helps settle the soil and completes the rehydration process. Following this, minimize watering until the first signs of green foliage emerge from the soil.
Overwatering during this initial phase is the most common cause of corm rot. Once shoots appear, maintain a consistent watering schedule, ensuring the top inch of soil dries out between applications. If planting in the fall in a cooler climate, have a layer of mulch or a protective frost cloth ready to cover the planting area if temperatures unexpectedly dip toward freezing.