Ranunculus bulbs may be planted in the fall or in the spring, but if you live in zones four to seven, start the bulbs indoors in the spring. Ranunculus bulbs resemble an octopus, with spiky legs that surround the main growth point. It's a good idea to soak the bulbs in warm water for three to four hours just prior to planting. Select a location in your garden with full-to-partial sun and good drainage for growing ranunculus flowers. If water puddles are still visible five to six hours after a hard rain, your soil does not drain well and you should look for a new site to plant ranunculus or work to improve your first choice. Add 3 or more inches of organic material to the flower bed to raise the soil levels and improve drainage. Compost, decomposed manure and peat moss will all work to raise the soil level. Ranunculus flowers grow best in a slightly-acidic soil, with pH levels between 6 and 6.5. Soil test kits are available at your local garden supply store and from online retailers. You can increase the pH level of your soil by adding lime, and decrease the pH level by adding aluminum sulfate.
The unusual leggy appearance of ranunculus bulbs makes it easy to tell which side should be facing downward when you plant them. The spiky legs should point down into the soil. Plant your ranunculus bulbs 2 inches deep and space them 4 to 6 inches apart for optimum results. The bulbs may be small, but the plants and flowers grow large, so give them room to flourish. Cover the bulbs with soil and water the soil thoroughly after planting. Fertilize the plants with a liquid-soluble fertilizer at the time of planting and sparingly throughout the growing period.
To plant ranunculus bulbs in containers, follow the same soil guidelines as for planting them in the garden. Select a container that drains well and place it in full sun for best results.
Ranunculus flowers typically bloom in the spring, but they will bloom at the end of summer the first year if you plant the bulbs in the spring. After the first year they will bloom in the spring. Water the plants well during the growing season, cutting the flowers for arrangements as you wish. When the blooming period ends, leave the foliage on the plants to soak up and store nutrients from the sun. When the leaves become yellow, usually at the end of the summer, remove them and stop watering the ranunculus. The plants will become dormant for a few months. Ranunculus flowers are hardy in zones 8 and above, though they will tolerate a light frost. Treat them as an annual in colder climates.