How to Grow Ranunculus Asiaticus
Ranunculus asiaticus are tender perennial flowering plants grown from underground tubers called corms. They produce densely petaled blooms resembling small camellias in the spring and summer. Hardy in USDA Zones 8 through 10, they are grown as annuals in cooler climates beyond their natural range. Ranunculus asiaticus thrive in sunny conditions and are best grown en masse in beds and borders or in cutting gardens.
Select a planting location with a full sun to partial daily shade exposure for your ranunculus corms and plants. Some afternoon shade will likely be welcome in particularly warm and or dry climates.
Plant the corms in a nutrient-rich, well-tilled and easy-draining soil. Amend the planting bed with compost or well-aged manure and a dose of granular bulb fertilizer. Ranunculus appreciate a slightly acidic to neutral pH soil so adding a pound or two of peat moss to the soil can boost the acidity gently and naturally.
Water your ranunculus regualrly to keep the soil evenly and lightly moist but not consistently wet. Ranunculus stems and corms can easily rot when over-watered so monitor watering carefully but do not allow the soil to dry out. Mulch around the base of the plants with an organic mulch such as shredded bark or cocoa bean hulls to hold moisture in and keep competitive weeds down.
Feed ranunculus asiaticus once or twice a year with a granular bulb fertilizer according to the label dosing guidelines. Water in the fertilizer well at the time of application.
Harvest fresh ranunculus blooms for cut flower arrangements just they begin to unfurl. Make your cuts at the base of the stem. Deadhead fading blooms as they wilt and droop. Don't be afraid to harvest and cut back dying blooms as this pruning will promote ongoing production of blooms.