How to grow ranunculus

Choosing a ranunculus

Choose a ranunculus that fits best with the growing conditions in your garden. Here are some ranunculus for specific sites and conditions:-

Moist, partial shade: use hardy, low-growing Ficaria verna that are closely related to Ranunculus, and flower in spring, dying down in summer to make space for other border plants. Lesser celadine (Ficaria verna subsp. verna) can spread as a weed in gardens but is a good early source of nectar in wildlife gardens.

Moist borders in sun: use double-flowered, clump-forming

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

Border ranunculus

Border ranunculus

Annuals are plants that complete their life cycle in one growing season. They are generally easy to grow from seed or can be bought as young plants from garden centres. Annuals are ideal for growing in summer containers and filling gaps in borders. Some examples of annuals include sunflowers, cosmos, sweet peas and zinnia.

annuals

Bedding ranunculus

Bedding ranunculus

Alpine ranunculus

Alpine ranunculus

Choose a ranunculus that has received the RHS Award of Garden Merit as it has been tested and perfoms well in the garden. 

Buying ranunculus

• Buy border ranunculus as pot grown plants, ideally in spring from garden centres or mail order
• Buttercups for wild flower meadows are available as seed and
  Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

  plug plants in spring by mail order. A limited range of seed is available by mail order from specialist suppliers of wildflower seed
• ​Buttercups for ponds and streams can be purchased as pot grown plants from specialist aquatic nurseries or by mail order, while seed is available from specialist suppliers of wildflower seed online
• Persian buttercups can be purchased as tubers, available in autumn or spring, or as young plants in spring from garden centres or by mail order. Seed is available by mail order but they are more easily grown from
  Tubers are swollen, usually underground, parts of a stem or root used to store food by the plant. They have buds that can produce new plants. Examples are tuberous begonia, cyclamen, dahlia and potato.

  tubers or young plants
• Alpine buttercups are available as pot grown plants from specialist alpine nurseries directly or by mail order

Grow hardy perennial ranunculus in any damp, garden soil that does not dry out, in sun or partial shade. Avoid planting in deep shade as they will not flower.

In borders, meadows, ponds and streams margins

Ideally, plant your plug plants or container grown ranunculus in spring, at the same depth they are in the pot. Sow seed for meadows during March and April or in September depending on the soil conditions. On lighter soils, autumn sowing allows the plants to germinate and establish quickly although some seed may only germinate in the spring. On heavier, water logged soils the seedlings or seed may rot in winter.

Bedding and pot ranunculus 

Soak the tubers of Persian buttercups (Ranunculus asiaticus) for a day, before planting. Then plant in containers from September to December with a loam-based compost with 20% added horticultural grit, to improve drainage and incorporate a slow-release fertiliser like Growmore. Place the tubers with the claws downwards, 10cm (4in) apart and cover with 5cm (2in) compost. 

Grow on in bright light, in a cool greenhouse or cold frame, with good air flow to prevent grey mould and aphids. Established plants can tolerate temperatures down to 0°C (32°F). Growing plants under cool conditions (below 15°C (59°F)) produces compact plants and delays flowering until April. Plants can be placed outside when all danger of frost has passed.

For outdoor flowering in autumn, plant tubers directly in the border up to June. Select a sunny spot with free-draining soil and add well-rotted compost, to help retain moisture. 

Bedding ranunculus

Bedding ranunculus

Alpine ranunculus 

These plants need gritty, humus-rich well-drained soils, in full sun and grow well in a scree bed or alpine house. When growing in pots, use a compost with equal parts loam, grit and leaf mould. These hardy plants may be short lived.

Alpine ranunculus

Alpine ranunculus

Watering

• Water seedlings and young plants regularly, ensuring the top 15cm (6in) of soil is damp but not soggy, in the first few months 
• Keep plants moist when growing and flowering

Feeding

• Feed border plants in spring when they start to grow with a balanced fertlilser, such as Growmore or bonemeal (70g per sq m or 2oz per sq yd)
• Plants growing in meadows, along edges of ponds and streams do not need feeding

Deadheading

• Remove flowers on alpine and border plants to encourage further flowering
• If growing Persian buttercups (Ranunculus asiaticus) for the vase, cut the stems before the flowers are fully open and they should last 10-12 days

Overwintering

• Most ranunculus are hardy so don't need any special care over winter
• Grow Persian buttercups (Ranunculus asiaticus) in a cool greenhouse in winter

Caring for older plants

• Some spring flowering plants such as Ranunculus repens and Ficaria spread rapidly and can become a nuisance
• Early flowering Ficaria die down in summer, so place the plant label under the plant. This way you can identify the plant if you dig it up by mistake
• Percian buttercups (Ranunculus asiaticus) are best grown as an annual and replaced every year

• Spring flowering perennials such as Fricaria, that die down in summer, are best split after flowering
• Summer flowering perennial ranunculus can be divided in autumn or spring. Many naturally increase from seed but division is quicker
• If growing Persian buttercups (Ranunculus asiaticus) from seed rather than tubers, sow in plug cells in September, cover the seed lightly and maintain at 15°C (59°F). Keep moist and frost-free during winter, potting into the final pots when they have four true leaves. Plants may flower in their first year before dying down
• In most other species, dormancy needs to be broken by exposure to winter cold. Harvest the seed when ripe but still green in spring and sow immediately, in pots. Use a gritty, loam-based compost. Expose the pots to the winter cold but keep them in a sheltered place such as a cold frame. Fresh seed often germinates in the following spring but older seed (black or brown seed) may take one to two years to germinate
• Aquatic ranunculus such as water crowfoot (Ranunculus aquatilis) and greater spearwort (Ranunculus lingua) can be divided in spring or late summer and cuttings taken after flowering. Alternatively sow seeds fresh and keep at 10°C (50°F)

Ranunculus are generally trouble free but can suffer from powdery mildew in dry conditions. Maintain good air circulation when growing plants in cold frames and greenhouses to prevent problems with grey mould and aphids.

Some ranunculus can spread rapidly and may need to be reduced. Lesser celandine can be especially problematic.