Persian buttercups (Ranunculus asiaticus) grow to a height of 1 foot, producing late spring flowers on 1- to 2-foot-tall stems. Plant the tubers in sunny garden areas or in containers on a deck or patio for showy spring flowers. The flowers can also be cut and placed in a vase to enjoy indoors.
When to Plant
Plant Persian buttercup tubers, often referred to as bulbs, in the garden in October or November in U.S. Department of Agriculture plant hardiness zones
Soak Persian buttercup tubers in warm water for two hours to hydrate them before planting.
Start Persian buttercup tubers indoors in containers one to three months before the last expected spring frost to get a jump on the season. Plant them 1 inch deep in 6- to 8-inch-wide containers with holes in the bottoms, using houseplant potting soil. Two to three tubers can be planted in each container. Water the freshly planted tubers and put them in a bright location. Maintain night temperatures of 45 to 50 degrees F and day temperatures of 60 degrees F. Allow the soil to become almost completely dry before watering. Transplant the plants into the garden after the last expected frost.
Clean, dry ranunculus tubers can be stored in a cool, dry area in a brown paper bag for up to one year.
Sun and Soil
Plant Persian buttercup tubers in fast-draining garden soil in full sun. If they're planted in slow-draining soil, where water tends to stand for five to six hours after a heavy rain, the tubers will rot. Mix a 2- to 3-inch depth of compost, sphagnum peat moss, well-aged manure or composted shredded bark mulch into the top 8 to 10 inches of clay or slow-draining soil before planting. Sandy or loam soil can be improved with the addition of organic matter, but it's not absolutely necessary.
Ranunculus plants are toxic to people, cats, dogs and grazing animals if eaten. The sap from leaves and stems can cause a rash.
Planting in the Garden
Dig holes 2 inches deep in sandy or loamy soil or 1 inch deep in clay soil. Plant transplants at the same depth they were growing previously. Make the holes slightly wider than the tubers. Space the tubers 6 to 8 inches apart from each other and other plants. Set the Persian buttercup tubers in the planting holes with the pointed ends facing down. Cover them with garden soil and water them generously.
Spread a 2- to 3-inch depth of organic mulch over the soil. Water the Persian buttercups when the top inch of soil becomes dry.
Planting in Containers
Persian buttercups grown as potted plants on the deck or patio should be planted in 10-inch containers with holes in the bottom. Plant one tuber 1 inch deep in each container. Set them in a sunny position and water them when the soil gets dry.