Are Ranunculus Perennial or Annual?
The ranunculus we cultivate for cut flowers (Ranunculus asiaticus) is a tender perennial similar to a dahlia. They are regarded as perennials because the foliage dies back annually, but the plant can survive underground, reemerging when spring arrives. However, they cannot endure very cold temperatures. Ranunculus plants are robust in USDA Zones 8-11, where temperatures generally remain mild enough for them to survive. Nonetheless, in most areas, even warm regions, they are grown as annuals, with new corms planted each year.

Growing Ranunculus as Perennial Plants
While ranunculus are perennial plants, you'll need to consider a few aspects to ensure they thrive year after year.

Winter Temperatures
Winter temperatures are the primary limiting factor because ranunculus corms cannot survive being frozen. If your soil freezes at all, essentially in Zone 7 and colder, your ranunculus won't make it. After frozen corms thaw, they will rot. Many flower farmers in Zones 6 and 7 plant ranunculus corms in the fall but protect them with a greenhouse or hoop house. If your soil freezes for only a brief period or infrequently, you might be able to cover your ranunculus corms with a thick layer of mulch and a low tunnel or small hoop house.

Drainage
Areas with warmer winters and soil temperatures that remain above freezing must still take drainage into account. Many warm regions experience cool but wet winters. Corms in soggy winter soil will rot.
If it sounds like rotting corms is a frequent issue with ranunculus, that's because it is. They’re prone to too much moisture and will turn to mush if the soil drainage isn’t ideal. Even if your garden is in Zone 8 or warmer, if the winter drainage, which can be vastly different from summer conditions, isn’t adequate, you’re better off digging up your corms and storing them somewhere dry and protected until spring.

Digging and Replanting Ranunculus Corms
Whether or not you can overwinter ranunculus in the ground, digging up the corms in the fall is a beneficial practice. Besides avoiding overly wet conditions, digging up the corms will help prevent overcrowding. Like dahlia tubers, ranunculus naturally multiply underground and over time form a dense cluster.
Digging up the corms, separating them, and then replanting them with appropriate spacing will result in more ranunculus flowers next year and keep the plants healthier. Overcrowded ranunculus are highly susceptible to powdery mildew and won't grow as well due to competition from neighboring corms.
If you live in a colder region and wish to save the corms for replanting next spring, you need to dig them up, shake off the soil, separate them, and store them over the winter in a dry, frost-free location.

Frequently Asked Questions

• How long does it take ranunculus to bloom?
• Ranunculus typically start blooming about 90 days after planting pre-sprouted corms.
• Will the ranunculus corms I dig and store be the same color next year?
• Yes, they will. Unlike reproduction via seed, corms are a type of vegetative reproduction, and daughter plants are identical to their parent.
• How should ranunculus corms be stored?
• Ranunculus corms aren't particular about storage. Dry them off, and keep them in a cool, dark, and dry place. They'll appear dry and hard and are resistant to anything except high humidity. Keep them safe from mice and other rodents.
• When should I plant ranunculus corms?
• If you are in USDA Hardiness Zone 8 and warmer, you can plant ranunculus in the autumn, around the same time you’d plant fall bulbs like daffodils and tulips. In colder regions, plant pre-sprouted ranunculus corms about four weeks before your last frost in spring and cover them with frost cloth as needed until the weather warms.
• Do deer eat ranunculus?
• While deer don't prefer ranunculus, they may nibble the tops while sampling other plants. Protect them with fencing, deer repellents, or other methods that work for you.