Ranunculus are a large genus of hardy or half hardy perennials.
Due to the large number of species the flowering season is species dependent and ranges from late in the winter until the summer.
Most Ranunculus flowers have cup shaped flowers, though many have double cups.
The range in height of Ranunculus means that where they can be grown is species dependent, ranging from rock gardens, through to borders or in mass.
Some common names for Ranunculus include Buttercup, Creeping Buttercup, Lesser Celandine, Greater Spearwort and Bachelor's Buttons. Latin names include Ranunculus flammula, Ranunculus glacialis, and Ranunculus repens.
Ranunculus montanus - Mountain Buttercup by Cliff1066™
Ranunculus eschscholtzii - Alpine Buttercup by Brewbooks.
Common Names: Buttercup, Water Crowfoot, Spearwort, Lesser Celedine, Makino, Bachelor's Buttons. Buttercup: Woodland; Creeping; Lapland; Smallflower; Pygmy; Swamp; Mount Cook; Californian; Utah.
Scientific Names: Ranunculus acris; R. aquatilis; R. calandrinioides; R. ficaria; R. lyallii; R. repens.
Life Cycle: Hardy perennial or half hardy perennial commonly grown as a half hardy annual by gardeners.
Height: 0.5 to 40 inches (1 to 100 cm).
Native: Central and Northern America, Mediterranean, Europe, Asia, Australasia.
Growing Region: Zones 4 to 9.
Flowers: End of winter, spring and/or summer.
Flower Details: Yellow, white, orange, red. Cup-shaped. Lustrous petals. Often has five petals.
Foliage: Broad. Lobed. Fine hairs.
Sow Inside/Outside: Cover seed. Roots: 2 inches. Sow in flats in the spring. Place flat in a bag and stratify in the fridge for three weeks. Sink flats in a shady area. Provide a glass/plastic cover. Germination time: two weeks to three months. Transplant seedlings to their final location with a spacing of 2 to 24 inches (5 to 60 cm).
Requirements: Light shade. Good drainage. Moist soil. Light poor soils. Summer cooling mulch. Regular watering during prolonged dry periods to keep the soil moist. Bring tubers indoors in cool areas for the winter. Propagate: dividing in the spring in cool areas, or in autumn in warmer areas.
Miscellaneous: Some species are classified as invasive.
Buttercups can be started from roots these should be buried about 5 cm deep. When growing Buttercups and other Ranunculus species from seeds it is best to start them in flats in the spring. Ranunculus seeds should be lightly covered once sown, then the flat put into a plastic bag and placed in the fridge for three weeks. The flat should then be removed from the bag and sank into a shady part of the garden and covered with glass.
Seed germination takes from two weeks to three months; as soon as the seedlings emerge transplant them to their final location. Buttercup (Ranunculus) prefer to grow in a partially shaded area or in sunny areas that have moist soils.
It is pretty easy to look after Ranunculus; they should be watered during prolonged dry spells or if growing in a sunny area. They like a cool soil so mulch the plants in the spring time. If you require more plants then they can be propagated by division in the spring or autumn.
Amazon USA PDF - Guide to Annual Plants