The vibrant, layered blooms of the Ranunculus asiaticus, commonly known as the Persian Buttercup, signal the arrival of spring and early summer color. Once flowering ends, the care provided determines the success of next season’s growth. This post-bloom period is a necessary phase where the plant prepares its underground storage structures, or tubers, for dormancy. Proper handling during this transition ensures the plant’s survival and its ability to re-flower vigorously the following year.
Cutting Back Spent Blooms and Foliage
The first step after the petals drop is to remove the spent flowers, a process known as deadheading. Snip the flower stem down to the nearest set of healthy leaves or to the base of the plant. This action prevents the plant from diverting energy into seed production, which redirects resources back toward the tubers.
It is necessary to resist the urge to cut back the remaining green foliage. The leaves must be left intact while green because they are actively performing photosynthesis. This process captures light energy and converts it into sugars, which are then stored as carbohydrates within the underground tubers.
Only after the foliage has naturally turned yellow or brown and withered should you cut it back, as this indicates the energy transfer to the tubers is complete. Prematurely removing the leaves starves the tubers, resulting in small, weak plants that may not bloom well the next season. Once fully withered, the foliage can be trimmed back to about an inch above the soil line, signaling the start of the dormancy preparation phase.
Preparing Tubers for Dormancy
The plant’s natural signal that it is ready for dormancy is the complete yellowing and browning of the leaves, which typically happens in late spring or early summer as temperatures rise. At this point, the above-ground material is no longer functional. Stop watering the plants once the foliage begins to yellow, allowing the soil to dry out completely, which helps initiate the drying process for the tubers.
The decision to leave the tubers in the ground or to lift them depends entirely on your climate. In regions with very mild winters (USDA Zones 8-10) and consistently well-draining soil, ranunculus tubers can often be left undisturbed to perennialize. However, lifting the tubers is necessary in areas with harsh, freezing winters or where summer humidity and heavy rainfall could cause the tubers to rot.
If lifting is required, wait until the foliage is entirely dried and brittle. Carefully use a garden fork to loosen the soil around the plant mass, avoiding direct contact with the brittle, claw-like tubers. Gently lift the entire clump and shake off any large, loose pieces of soil. The tubers must then be placed in a single layer in a dry, well-ventilated area, away from direct sun, for several days to cure and dry completely.
Storing Ranunculus Tubers
After the initial curing period, the tubers should be checked for any remaining soil, which can be lightly brushed off once they are fully dry. The storage environment must be managed to prevent both desiccation and rot. The goal is to maintain a cool, dry, dark, and well-ventilated space until the next planting season.
An ideal storage temperature range is approximately 50 to 55°F (10 to 13°C), which is cool enough to keep them dormant but safely above freezing. High humidity is a major risk, as it encourages fungal growth and rot, so the environment must remain dry. A basement or cool pantry often provides the proper conditions, provided there is good air circulation.
The fully dried tubers should be placed into breathable containers rather than sealed plastic bags. Mesh bags, paper bags, or cardboard boxes work well. You can nestle the tubers in a dry, inert material such as peat moss or vermiculite for additional moisture regulation and protection. Periodically check the stored tubers throughout the dormant period for any signs of mold or shriveling. Discard any compromised tubers to prevent the spread of decay to the healthy stock.