How to Grow and Care for Persian Buttercups

Persian buttercups (Ranunculus asiaticus) are beloved for their brilliantly colored and ruffled petals, tall stems, and long vase life. Their color range—from bright pink, red, and purple to cream, pale yellow, and orange—makes them a favorite at florist shops and in wedding bouquets. Plus, the  corms are easy to find at nurseries and in catalogs, and they can be planted in the fall or spring, depending on the climate. The plants grow fairly quickly and should provide rose-like flowers with tissue-thin petals above lush foliage with finely cut, fern-like leaves in the late spring to early summer.

Buttercup is toxic to animals and humans.

Persian Buttercup Care

In warmer climates, Persian buttercups can be planted outdoors in the fall. But in colder areas where the temperatures dip well below freezing for extended periods, wait to plant the corms until early spring once the threat of frost has passed, or start the corms indoors in pots about eight to 12 weeks before your area's projected last frost date. Plant the bulbs with the end that looks like claws facing down, and cover them with one to two inches of soil.

Corms planted in the fall generally bloom in early spring and continue producing flowers for six to seven weeks, while those planted in early spring tend to flower by mid-spring and continue for four to six weeks. Deadheading (removing spent flowers) can promote additional blooming.

If you live in USDA hardiness zones 8 to 11 and wish to try growing Persian buttercups as perennials, leave them in place and allow the foliage to die back naturally at summer's end. Dormant corms appreciate dry, cool conditions; too much moisture can cause rot. If you live outside of the plant’s hardiness zones, you can try digging up the corms and storing them in a cool spot indoors for winter covered in a dry medium, such as sand. However, successful storage is difficult, so many gardeners opt to grow these plants as annuals and replace them with new plants each year.

Light

Persian buttercups prefer a planting site that gets full sun (at least six hours of sunlight on most days) to grow and bloom best.

Soil

These plants like to grow in sandy or loamy soil that has good drainage and a slightly acidic soil pH. If you have heavy soil, amend it with compost or plant in raised garden beds where you can control the soil makeup.

Water

It's not necessary to soak the bulbs in water before planting to stimulate growth. But if you decide to soak, don't overdo it; one to four hours will be enough without encouraging mold growth. Water the bulbs well upon planting, and then withhold water until growth appears to avoid rot. Once the plants are established, they prefer moderately moist soil, so water only when the soil begins to dry out.

Temperature and Humidity

Persian buttercups prefer cool spring weather and will begin to go dormant once summer temperatures pass 90 degrees Fahrenheit. A layer of mulch around the plants can help to keep the roots cool and extend their growing period. They're not overly picky about humidity, though very high humidity can cause the bulbs to rot and kill the plant.

Fertilizer

Mix some compost or bulb fertilizer into the soil of the planting site before planting your corms. If growing in a container, fertilize the plants biweekly with a water-soluble fertilizer. For the amount to use, follow the product label instructions.

Types of Persian Buttercup

There are multiple varieties of Persian buttercups that range in appearance, including:

• Ranunculus asiaticus 'Tecolote Red': This variety has deep red blooms that measure three to six inches across.
• Ranunculus asiaticus 'Bloomingdale': These plants produce large flowers in several colors.
• Ranunculus asiaticus 'Café': This variety sports bronze-colored blooms.
• Ranunculus asiaticus 'Flamenco': These flowers are a mixture of yellow and orange with red around the edges.
• Ranunculus asiaticus 'Merlot': These plants can feature both deep red-purple flowers and white flowers.

Pruning

If you are keeping this plant indoors, trim the foliage as desired to keep an appropriate shape and size. Whether indoors or outdoors, deadheading the flowers as they fade can lead to more blooms and a tidier plant. If you're growing the plant as a perennial in the garden, do not trim the foliage after blooming, Allow it to die back naturally. The foliage will absorb sunlight and provide nutrients to feed the corm and produce flowers the following season.

Propagating Persian Buttercup

You can propagate Persian buttercup through either division or seed.

1. When propagating by division, wait until fall to dig up the corms with a shovel. Many of them should have created offsets, or tiny seed corms.
2. If you live in hardiness zone of 8 or above, you can simply divide the corms with a sharp knife and immediately plant the offsets in a new location. Plant them with the fingers pointed downward about one to two inches deep. Water them well and keep the soil evenly moist, watering every couple of days until you see new shoots emerge in a few weeks.
3. If you live below zone 8, Persian buttercup is grown as an annual, but you can store the corms for the winter and replant them in the spring. Clean off excess dirt and store them in a well-ventilated, cool location away from direct sunlight, in a crate or box with coir, a sustainable alternative to peat moss. In the spring, soak them for one hour in warm water, then plant them outside as described above.

How to Grow Persian Buttercup From Seed

To collect seeds from your Persian buttercups, wait until the flowers begin to fade, then cut them from the plant. Place them in a paper bag to dry for a week or so, then shake the bag vigorously to knock the seeds loose. Keep in mind the seeds are small, so take care when opening the bag.

Start the seeds indoors a few weeks before the final frost date in your area. Sow them on top of evenly moist soil and keep them in daytime temperatures of 60 to 70 degrees Fahrenheit. Keep them out of direct sunlight and drafts. Germination should occur in roughly two weeks. Provide a good light source for seedlings. Once seedlings have four sets of true leaves, they are ready to be transplanted into other containers but don't plant them outside until all danger of frost has passed. Harden off seedlings before planting in the garden.

Note: seeds collected and grown from hybrid varieties will not come true to parent plants.

Potting and Repotting Persian Buttercup

Persian buttercups are often grown in containers, especially outside of their hardiness zones. Use containers with ample drainage holes at the bottom. Fill a container with an all-purpose potting mix that drains well. Space the corms three to four inches apart if planting in the same container and bury them about two inches deep in the soil. Water the corms well after planting and place the container where it will receive full sun.

Overwintering

In their hardiness zones, overwintering Persian buttercups is as simple as cutting them back to the ground before winter hits and perhaps giving them a layer of mulch. In zones where the winters are harsher, you can try digging up the corms and storing them in a dry place in a medium like coir. Keep in mind, however, that this often doesn't work well. If you have Persian buttercups in containers, bring them inside to a warm location for the winter.

Common Pests and Plant Diseases

Several pests are drawn to Persian buttercups, including spider mites, leaf miners, and aphids. These pests will feed on the leaves and render them splotchy, withered, and with a yellowish-brown color. Keep aphids away by spraying the plant with a mixture of water and mild dish soap in a bottle. An organic pesticide can help alleviate problems with spider mites and leaf miners.

Diseases that can affect Persian buttercups include powdery mildew, necrotic spot, rust, and tomato spotted wilt virus. All of these issues can curl the leaves and turn them yellow, and in some cases, can kill the plant. The best defense is prevention: provide excellent air circulation around the plants, water the soil and not the plant itself, and rotate plantings annually.

How to Get Persian Buttercup to Bloom

If your Persian buttercups aren't blooming, make sure they have the proper amount of water⁠—about one inch per week⁠—and that they don't have too much fertilizer, as high nitrogen levels can promote foliage growth but inhibit blooms. Mulch with coco hulls, straw, or bark to maintain moisture levels after watering.