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How to grow ranunculus
Here’s our ultimate guide on how to plant ranunculus bulbs. Producing lush foliage and stunning rose-clustered blooms from spring to early summer, ranunculi come in a huge range of colours and shapes. They look fantastic growing through beds and borders, or planted en masse in patio containers. The flowers are also ideal for cutting, and last for weeks in a vase.
Here’s how to plant, grow and split ranunculus bulbs for spectacular spring displays.
What are ranunculi?
Ranunculus is a genus of flowering perennial plants, found in the same family as buttercups and larkspur, and native to southern Europe and southwestern Asia. The most commonly grown ornamental ranunculus is R. asiaticus, also known as a ‘persian buttercup’ or simply ‘ranunculus’.
Ranunculi are usually grown from bulbs (tubers), which have a claw-like appearance. They are available at the beginning of autumn or early spring. Alternatively, ranunculi can be raised from seed or split from existing mature plants.
When should I plant ranunculus bulbs?
Provided you live in a mild area, the best time to plant ranunculus bulbs is autumn. The flowers will appear the following spring. Autumn-planted bulbs tend to be more prolific than spring-planted ones, and flower for longer.
You can also plant your bulbs in the early spring after the risk of frost has passed. You’ll get a slightly shorter period of flowers, which should appear in late summer, roughly 90 days after planting.
Where to plant ranunculus bulbs
In milder areas, plant your ranunculus bulbs straight outdoors in autumn to overwinter in their flowering positions. Ranunculi reach a height of between 20 and 30cm tall, so place them at the front of a mixed border for lovely compact colour.
If you live in a colder area that regularly sees hard frosts through the winter, plant your autumn bulbs in containers to overwinter in a polytunnel or greenhouse. Move your container grown ranunculi outdoors come spring, and place in a prominent position to enjoy.
How to plant ranunculus bulbs
Place your ranunculus bulbs in water at room temperature for a few hours to hydrate them before planting. This stage isn’t necessary, but it will speed up the sprouting process. After soaking, the bulbs should increase in size and have a plump look. Cover the bulbs in a tray of compost and leave to sprout for a few days.
Prepare the soil by mixing in well-rotted manure or good-quality general-purpose compost. Plant your hydrated bulbs about 2 to 3 inches deep with the ‘tentacle’ side of the bulb facing down. Choose a spot in full sun, away from strong wind, and with good drainage. The bulbs should be spaced about 9 inches apart to give them room to grow, and watered in well. Mark the spot with a wooden label so you don’t forget where they are!
For container-grown ranunculi, add plenty of grit to the base of the pot before filling it with a quality multipurpose compost. Add some extra grit to the compost to improve the drainage. To plant the bulbs, follow the same process as above, making sure that the ‘tentacles’ point down. Label the pot after watering in your bulbs, and place it in a sheltered, sunny position away from strong wind.
How to care for ranunculi
After planting, make sure you keep watering the developing plants well, especially during dry periods. However, don’t allow the soil to become waterlogged as this may cause the bulbs to rot. Deadhead your ranunculi regularly during flowering to encourage more blooms and to allow the bulbs to retain energy for next year instead of putting it into seed production.
If your plants are threatened by frost, protect them with a layer of horticultural fleece, or move your containers into a sheltered area. Alternatively, lift your outdoor planted bulbs after the foliage has died back in autumn, and store them over winter in a dry cool place, ready to replant in the spring.
Best ranunculi varieties to try
Ranunculi have a great ‘shelf life’ making them ideal for cut flowers, so try growing a broad mix of varieties for cutting and displaying indoors. Reds and pinks look great when planted together, or try a bright yellow mixed with white for a sophisticated spring display.
Alternatively a ‘peony’ type ranunculus like ‘Marshmallow’ produces very dense blooms with layers of paper thin petals on upright stems, ideal for cutting or enjoying at the front of the border.