Ranunculus Asiatic does best in mild winter areas with long, cool springtime temperatures. Profuse, dazzling displays of white, yellow, gold, orange, salmon, pink, rose, red, pastels and even bicolor picotees deliver superior cut flowers and brilliant, exciting mass plantings that last up to six weeks. Ranunculus can be grown as winter-hardy perennials in USDA Zones 8 to 11 to about 10 degrees Farenheit. The bulbs are inexpensive, and the plants are easy to grow and maintain and make gorgeous annual plants in cooler regions.
Choose your ranunculus bulbs, or tubers, carefully. The bulb size indicates the number of flowers the mature plant will generate. The claw-like bulbs look kind of like a little octopus and are typically available in four grades, or sizes. Jumbos have a diameter of about 7/8 inch and will produce about 35 cutting stems. Ones, twos and threes are smaller respectively, and you'll get comparatively lower numbers of blooms from them.
Plant jumbo ranunculus tubers one to two inches deep and eight to 12 inches apart in a well-draining location in full sun with the claw pointing downward. Zones 8 to 11 should plant between October and November. Ranunculus can be started in cooler regions in the spring one to two weeks before the last predicted frost. Fall planted tubers will bloom in March, while those planted in the spring will flower during June and July.
Water thoroughly so the soil is evenly moist but not soggy. As long as the location remains moist, you won't need to water again for another 14 to 21 days, when the first sprouts appear.
Apply a dilute all-purpose blooming fertilizer. Thereafter, feed the ranunculus according to the manufacturer's instructions throughout the growing season.
Mulch with straw or bark to encourage moisture retention and for weed control. Continue to water throughout the season just enough to keep the soil evenly moist.
Cut the flowers for seven-day indoor displays when the buds first show a little color. The best time of day to do this is very early in the morning, when ranunculus plants still retain maximum moisture content. Remove flowers from the plants as soon as they fade to encourage continuous blooming.
Feed the ranunculus one more time when the last blooms begin fading. Stop watering the plants when foliage begins to turn yellow and die back.
Start watering again in the fall for perennial ranunculus to return the following spring in Zones 8 to 11.
Lift tubers after the flowers have all faded and the plants have completely dried out if you want to save them to plant next year in zones other than 8 to 11. Cut off the tops and store the tubers in vermiculite in a cool, dark, dry location. Otherwise, just treat the plants as annuals, leaving them where they are to die off.