Ranunculus - Key Growing Information
Soaking: Soaking fully rehydrates the dry, dormant corms and starts them growing. Soak for 8–12 hours in water at 77°F (25°C), keeping every corm under water the whole time.
Chilling Treatment: After soaking, chill the corms at 40–50°F (4–10°C) for 3 weeks. You can do this in cold storage, or by planting straight into beds while the soil is in that range. In cold storage, keep them loose in peat or vermiculite, or in soil in seedling trays. For more on chilling, see our Ranunculus Production Guide.
Planting and Sprouting: Once soaked and chilled, corms can go straight into the ground or be grown as transplants. Either way, sprouting and shoot growth take about 2–4 weeks at 55–60°F (13–16°C). Loose corms: plant with the center facing up and the claw-like roots pointing down, taking care not to damage the roots, and cover with 1/8–¼" of soil. Transplants: after chilling them in seedling trays (see our Ranunculus Production Guide for details), grow at 55–60°F (13–16°C) until roots and shoots form and plants are ready to go out. Water the trays well and keep the soil moist but not soggy.
Light Preference: Sun.
Plant Height/Stem Length: Butterfly types: 18–36". Romance types: 14–24".
Plant Spacing: Butterfly types: 10–12" apart in rows 12–14" apart. Romance types: 6–8" apart in rows 8–10" apart.
Hardiness Zones: Usually grown as an annual in a tunnel or greenhouse. In USDA Zones 7 and warmer, ranunculus can perennialize outdoors. Established plants can handle light frost, but avoid freezing temperatures, and never let unsprouted corms freeze.
Vase Life: Lasts about 10 days in the vase. Put cut stems straight into cold water and keep them at 34–40°F (1–4°C).
Harvest: Cut in early morning whenever you can, using a knife or snips to cut stems at ground level; pulling stems can uproot or damage the plant. The harvest window runs 2–4 weeks depending on conditions, and steady temperatures above 70°F (21°C) can push plants into dormancy, shortening the season and lowering bloom quality. Butterfly types: cut when 2–3 flowers on the stem show color and one is open. Romance types: cut at the "marshmallow stage," when buds have colored and feel soft and springy but haven't fully opened. For the biggest, showiest blooms, let flowers open and close for 3 days before cutting.
Soil Requirements: Cool, moist soil with good drainage, ideally pH 5.8–6.3 and EC (electrical conductivity) of 1.3–1.5.
Pests and Disease: Rodents go after both corms and plants, so protect the crop from them at every stage. A fungicide treatment during sprouting can greatly cut losses to root rot.
Uses: Cut flower.
Scientific Name: Ranunculus asiaticus
Alternate Common Names: Persian buttercup, Persian crowfoot, Asian buttercup.
