The allure of ranunculus is undeniable, as its versatility and striking beauty have captured the hearts of many. With a wide range of varieties to choose from, this charming flower offers an abundance of options: from solitary blooms to those adorned with profuse petals, and hues that span the spectrum from soft pastels to rich purples and reds.
Whether you’re envisioning lush vases filled with whimsical blossoms or seeking a hardy groundcover for your garden, ranunculus is an excellent addition to any floral collection.
What is Ranunculus?
Ranunculus, a genus within the Ranunculae family, encompasses approximately 1800 species of plants, commonly referred to as buttercups, water crowfoots, figworts, Persian buttercups, and spearworts. Beyond their visually striking appearance, these plants have been used by Native Americans for centuries to treat various ailments, including body aches, skin disorders, and diseases. Despite being toxic when ingested, the plant’s versatility has been harnessed for medicinal purposes.
While some species are tender perennials that cannot withstand frost, most buttercups thrive in cooler climates with temperatures that are neither too cold nor too warm. In colder regions, tender species are often treated as annuals but will return in USDA Hardiness Zones 8-10. Conversely, other species can tolerate harsher conditions and remain hardy down to Zone 2.
Corms, resembling octopuses at first glance, serve as the primary means of propagation for most buttercup varieties, although seeds and root division can also be used depending on the specific type. As the plant dies back at the end of the growing season, energy is redirected to the roots and corms, allowing them to regenerate and return the following year. Bloom times vary across species, typically occurring in the spring to early summer period.
The diversity of ranunculus is further characterized by distinct flower shapes and colors, leaf sizes, and shapes, with many unique color combinations available, including two-toned pastels, deep hues, and vibrant shades.
Top 7 Ranunculus Species to Grow
While it’s true that the vast array of buttercup species, cultivars, and hybrids could fill an entire day’s worth of listings, let’s instead delve into the top ten most widely recognized and accessible ranunculus species for a more focused exploration.
Persian Buttercup
Persian buttercup (Ranunculus asiaticus), native to the Mediterranean, southwest Asia, and southeastern Europe, has gained widespread recognition for its stunning beauty. Commonly referred to as ranunculus, this versatile flower is cherished by florists, flower farmers, and budding growers alike. Its delicate petals are arranged in multiple layers on sturdy stems that can reach up to 24 inches in height. The foliage is a vibrant green color and primarily grows from the base of the plant.
One of the most striking aspects of Persian buttercup is its extensive range of color tones, including pink, red, orange, white, pale yellow, cream, and purple. This versatility has led to its widespread use in flower arrangements, where it can maintain its freshness for up to seven days. When grown in USDA Hardiness Zones 8-11, Persian buttercup thrives in well-draining soil with moderate moisture.
However, for those living outside of these zones, it can be successfully treated as an annual by keeping the plants cool and sheltered from full sun. Several notable cultivars have emerged within the Persian buttercup family, including ‘Tomer Picotee’, which boasts paper-thin, multi-layered blooms with a striking rose-like form. This highly sought-after variety is particularly prized for its use in wedding arrangements.
The term ‘Picotee’ refers to the darker tone that borders the central part of each petal. For gardeners looking for an added layer of visual interest, the ‘Tecolote’ series from California offers a unique treat. These double, peony-shaped flowers bloom at the beginning of spring and can persist into mid-spring if planted later in the fall. The range of colors available includes fairytale pink, salmon, merlot, yellow, and white hues.
Strong green foliage grows predominantly from the base of each plant, reaching heights of 18-24 inches. The Amandine Rose’ cultivar stands out for its smaller stature, with delicate petals arranged in multiple layers on stems that reach 10-15 inches in height. Its dark green foliage primarily grows from the base of the plant and is particularly heat-tolerant, resulting in a longer blooming period.
This variety can be grown in full sun or partial shade and thrives in USDA Hardiness Zones 7-11, though it can be successfully treated as an annual in zones 3-6. Lastly, for those seeking a dramatic statement piece, the ‘Iceberg’ Persian buttercup is sure to impress. Its enormous white blooms, reaching up to 5 inches in diameter, are arranged on stems that can reach 12-24 inches tall and are accompanied by basal greenery. This variety is tolerant of partial shade and prefers well-draining soil.
It thrives in USDA Hardiness Zones 7-10, though it can be successfully treated as an annual in zones 3-6.
Early Buttercup
Early Buttercup (R. fascicularis) is an exceptional choice for small spaces or rock gardens, as it can survive dry conditions once established. This charming ground cover option grows 4-12 inches tall and boasts striking yellow petals with a reflective coating that gives them a radiant appearance. One of its notable features is its ability to spread via tuberous roots and reseed readily if allowed to mature.
Native to the dry prairies, open woodland areas, and eastern regions of North America and Canada, this cold-tolerant buttercup thrives in Zones 3-7, making it an excellent option for those living in colder climates.
Mount Cook Buttercup
The giant buttercup, scientifically known as Ranunculus lyallii, is a remarkable species that boasts the largest blooms of its kind. Its white petals are beautifully accentuated by a golden yellow center, making for a striking visual display. Native to the mountains of New Zealand, this evergreen summer-flowering plant was originally referred to as the Mount Cook lily, despite not being a true lily. Its widespread cultivation worldwide is testament to its enduring appeal.
This ranunculus species grows in clumps, spreading up to 1-2 feet wide and reaching heights of 24-36 inches. It thrives in challenging environments, preferring damp conditions and well-draining soil. However, it does struggle in hot areas, making it a more demanding choice for even the most experienced gardeners. One of its greatest advantages is its cold hardiness, allowing it to flourish in zones 3-11.
Snow Buttercup
Snow buttercup, classified under the perennial herbaceous ranunculus category (R. nivalis), thrives in the Arctic and Alaska environments where it begins to bloom as soon as the snowcover recedes. Retaining remnants of its traditional buttercup appearance, this sunshine-yellow bloomer emerges from June to August, reaching a height of up to six inches during the growing phase and expanding to around ten inches when fruiting.
Once established, allow for sufficient space as this adaptable plant will naturally spread and prove an excellent ground cover option. With minimal care requirements in humus-rich soil and partial shade, snow buttercup is an ideal candidate for Zones 2-8, boasting extreme cold hardiness.
Italian Ranunculus
Italian buttercups, while not a distinct botanical species, are actually tissue clones bred in Italy to combine the best traits of Persian ranunculus for use as cut flowers. This results in cultivars like Cloni Success and Elegance Venere, which offer unique characteristics. For instance, Elegance Venera boasts peony-like blooms with ruffled, swirling petals and a slightly off-centre tone, all on stems that reach 18-24 inches tall – a departure from the more typical Persian buttercup look.
These tissue clones thrive when planted in the fall, blooming again in the spring, and prefer full sun and well-draining soil that is moderately moist. They are suitable for USDA Hardiness Zones 8-10.
Canary Buttercup
The buttercup species, R. cortusifolius, boasts vibrant yellow petals with a small, intricate center that shines like polished gold. This natural spreader thrives when given partial shade and consistently moist soil, allowing it to self-seed over time. As the seasons change, it dies back in the fall only to re-emerge anew when conditions are favorable. Its compact growth habit spans approximately 8-12 inches, with the flowers standing tall above the broad, basal leaves. A hardy perennial, R.
cortusifolius is well-suited for zones 8 through 10, making it a delightful addition to any garden.
Lesser Celandine
Ficaria verna, formerly known as R. ficaria, has a rich history spanning across Asia and Europe, where it has established itself naturally. Its charm lies in its bright yellow blooms that flourish against a backdrop of lush green leaves. Interestingly, various cultivars offer unique leaf patterns, featuring mottled cream and green hues or even deep purples.
This adaptable species can thrive in areas prone to seasonal flooding, but requires well-draining soil to prevent waterlogged roots from hindering growth. Ficaria verna is hardy in Zones 4-9; however, it’s essential to note that it has the potential to become invasive in certain regions. Despite its reclassification outside the Ranunculus genus, Ficaria verna can be grown and maintained similarly, offering a visually striking addition to any garden.
Propagating Ranunculus
Ranunculus enthusiasts have two primary methods to propagate this gorgeous flower: sowing seeds and planting corms. For those seeking a more instant gratification, many nurseries offer live ranunculus plants for purchase during the spring season, ideal for transplanting into your own garden.
Growing from Seed
When starting seeds, fill pots with high-quality seed starting mix and lightly cover the seeds. Maintain a consistent level of moisture, but avoid overwatering as they germinate. Position the containers in an area with bright, indirect light. As the seeds take around 20-30 days to sprout at a temperature of approximately 50°F, ensure the soil remains steady at this temperature. Once seedlings emerge, shield them from pests and direct sunlight.
A consistent temperature of 55°F will also help them thrive.
As the seedlings grow, they require an extended period of cool temperatures to establish themselves. Only when they’ve developed four sets of leaves and all danger of frost has passed can you transplant them outside. Before doing so, allow the seedlings to harden off by gradually introducing them to outdoor conditions.
When planting outside, newly-arrived seedlings may need protection from brief heatwaves.
Provide shade during the hottest part of the day using shade cloth. Keep in mind that seeds harvested from your flowers might not produce identical results, so be prepared for some variation.
Growing from Corms
When it comes to planting ranunculus corms, timing is everything. Not all corms are created equal, and some thrive in the fall while others do better in the spring. Before you start planting, make sure you know which type of corm you’re working with. Spring-planted corms tend to bloom later, whereas those planted in the fall emerge earlier. To get your corms ready for planting, begin by soaking them in room-temperature water for a few hours to rehydrate them.
At this point, you have two options: pre-sprouting or direct sowing. Pre-sprouting allows you to identify any dead corms and gives you a head start on growth. If you choose to pre-sprout:Fill trays or pots with two inches of seed starting mix that doesn’t require drainage holes. Place the corms, tentacles facing down, into the prepared containers, then cover them completely with soil mix. Keep the containers in bright, indirect light and a temperature range of around 50°F.
Water the soil when it feels dry to the touch, aiming for a slightly moist consistency rather than wet or too dry. Every few days, check on your corms to see if they’re sending out white roots. Once you notice this, you can move them to their final location in the garden. Most ranunculus varieties shouldn’t be exposed to outdoor temperatures until they consistently reach 45°F or higher.
If direct sowing: Plant the corms three inches deep and space them according to the specific variety you’re growing. Keep in mind that corms need temperatures below 50°F to start sprouting, so plant them when it’s cold but not freezing. If your climate doesn’t typically experience these conditions, pre-sprout as described above. To protect emerging growth from extreme temperatures and pests, use floating row covers, polytunnels, or cloches.
Be cautious not to overwater, as this can lead to root rot. Ensure the soil remains moist but never wet.
Caring for Ranunculus
For optimal growth, most ranunculus varieties require full sun to produce flowers, although some species may tolerate partial shade. As we’ve previously mentioned, these flowers tend to thrive in cooler climates when paired with happy pansies. To ensure the plants’ well-being, it’s crucial to maintain a consistent water schedule. Watering should be done only when the top inch of soil feels dry to the touch, aiming for a texture akin to a well-wrung sponge.
When planting ranunculus, incorporating a good compost and applying a balanced fertilizer or fish emulsion on a monthly basis will promote healthy growth. In warmer months, layering straw or leaf mulch can provide protection and aid in water retention. However, it’s essential to note that all buttercup types are toxic to pets, livestock, and humans, potentially causing skin irritation or stomach upset if ingested.
When the plants have died back, corms should be carefully dug up and stored in dry, dark containers with adequate airflow until re-planting is possible. This precautionary measure helps prevent corm rot caused by freezing temperatures below 25°F.
Companion Plants.
Brighten up your garden or vase arrangement with these vibrant and unique flowers: Calendula, known for its bright yellow petals and strong fragrance; Larkspur’s statuesque spikes of blue, pink, or white blooms; Delphinium’s towering stalks adorned with majestic spikes of blue or white; Snapdragon’s tall, slender stems featuring tubular flowers in shades of red, orange, and yellow; Foxglove’s elegant, bell-shaped blooms in hues of white, pink, and purple; Sweet Pea’s intoxicating fragrance and delicate, pastel-hued flowers; Iceland Poppy’s delicate, crepe-paper-like petals in shades of pink, orange, and yellow; Pansies’ velvety-textured, brightly colored blooms; Candytuft’s wispy, white or cream-colored stems featuring tiny, star-shaped flowers; Linaria’s delicate, spiky blooms in shades of blue, pink, and white; African Daisy’s cheerful, daisy-like blooms with a sunny disposition.
Each one is sure to add its own special touch to your outdoor space.
Pests, Problems, and Care
While ranunculus are renowned for their finicky nature, it’s not entirely unfounded. These flowers can be quite demanding, and gardeners may find themselves facing a range of challenges when attempting to cultivate them. One common issue is the presence of herbivores, which feed on the delicate foliage and stems of these plants. In addition to these pests, ranunculus are also susceptible to various diseases that can quickly decimate an entire crop if left unchecked.
Herbivores
Ranunculus corms are generally spared from the appetites of rabbits and deer, but they do have some underground predators to contend with. Moles, squirrels, mice, and chipmunks have been known to dig up these corms in search of a tasty snack.
To protect your Ranunculus from these pests, consider taking steps to deter them from accessing the corms. One simple method is to cut out the bottom of plastic plant pots and bury them around the base of the plants.
This physical barrier will make it difficult for moles and other burrowing animals to dig up the corms.
Alternatively, you can start your Ranunculus off in a pest-free environment, such as a basement or garage, before transplanting them outside. This allows the plants to become established and strong enough to resist any potential attacks from these pests.
Pests
Ranunculus plants are often plagued by a variety of pests, including aphids, thrips, mealybugs, nematodes, and spider mites. These common culprits can be identified by the first signs of infestation, which can be addressed with a quick spritz of insecticide or a homemade alternative if desired. However, pests tend to become a major issue when ranunculus struggle in hot weather or poor gardening practices are at play.
As these plants begin to sprout, they can attract unwanted visitors like slugs and snails, as well as birds seeking a tasty snack.
Diseases
When cultivating corms, it’s essential to ensure they’re not subjected to excessive moisture during germination or growth. Over-watering can lead to the development of rot and mold, compromising the health of your plants. To prevent fungal diseases, maintain a well-ventilated growing area by providing sufficient airflow. Additionally, make sure to keep corms at a safe distance from one another to reduce the risk of infection.
Unfortunately, these plants are susceptible to various diseases, including powdery mildew, pythium or phytophthora rot, and botrytis blight.
