How to Grow and Care for Ranunculus Bulbs

Ranunculus is a beautiful flower that looks like a cross between a rose and a peony. It’s one of the most popular flowers for bridal bouquets and a favorite at florist shops.

Because ranunculus needs a mild climate to survive year round, many gardeners in colder climates avoid planting it. However, by following the right steps, you can easily grow this show-stopping, romantic flower in your home garden- no matter where you live.

Here’s a complete guide on how to grow and care for ranunculus bulbs in any gardening zone.

What Is Ranunculus?

Also known as Persian buttercup, ranunculus (Ranunculus asiaticus) is a cool season flower that blooms in early to late spring.

Flowers bloom at the end of long, graceful stems and have layers of ruffled petals in a wide range of colors. In fact, ranunculus has one of the largest color ranges out of any flower. You can find cultivars in shades of pink, purple, red, orange, yellow, and cream as well as many combinations and in-between shades.

Many varieties of ranunculus are lightly scented, making them even more attractive. They are favored as a cut flower because of their color, appearance, and long vase life.

Ranunculus grows from what are often referred to as ‘bulbs’ but are technically known as ‘corms’. They are very similar to bulbs and are planted in much the same way.
Ranunculus are very popular as a cut flower and in bridal bouquets because of their huge, delicate, beautiful blossoms. They grow from tubers known as “corms” and bloom in the spring.

Much like daffodils and other spring bulbs, ranunculus appears and blooms in the cool weather of spring before fading away as the heat of summer comes on. The exact bloom time will depend on your climate and when you plant them.

Who Can Grow Ranunculus?

After hearing the description of ranunculus, you might be wondering why every gardener doesn’t have some in their backyard.

The main reason ranunculus isn’t more popular with home gardeners is because it’s only a perennial in USDA planting zones 8-11. It may survive winters with extra protection in zone 7, but it won’t be a consistent perennial.

So does that mean gardeners in cold regions are out of luck?

Actually, ranunculus is fairly easy to grow as an annual and can be treated as such by gardeners who can’t grow it as a perennial. It takes a bit more preparation than other plants do, but the extra effort is well worth it.

The other reason growing ranunculus as an annual is a good option is because it’s very inexpensive and widely available. You can buy the corms (bulbs) at many retail stores, garden stores, and online mail-order nurseries.

Ranunculus bulbs are relatively inexpensive, which makes them available to gardeners in colder climates to grow as an annual. They can be started indoors to get a jump on the season or planted directly in the ground.

This guide will give you growing and care tips for ranunculus as both an annual and perennial, so you’ll know how to grow it in your specific region.

Top Cultivars

Ranunculus can grow anywhere from 8 inches to 2 feet tall. You can select a cultivar based on mature height as well as flower color to make sure you get something that fits your growing space.

Here are some of the top choices:

• ‘Tecolote Flamenco’– This cultivar is a beautiful blend of yellow, apricot, and deep orange. Plants can grow up to 2 feet tall and individual blooms get up to 5 inches across.
• ‘Tecolote Cafe’– This is a show-stopping cultivar. The huge blooms are a mix of terracotta, gold, and bronze. Plants grow up to 2 feet tall.
• ‘Tecolote Salmon’– ‘Salmon’ has a soft peachy color, which is perfect for spring bouquets. Plants are more compact and grow 12-16 inches tall.
• ‘Giant Mixture’– If you can’t choose just one color, get this mix of almost every shade. You’ll get pastels, creams, bright rainbow colors, and deep purple. All grow up to 2 feet tall.

A rainbow mixture of ranunculus is the perfect way to brighten up your garden in the spring. Plant something like the ‘Giant Mixture’ en masse for the greatest effect.

• ‘Purple Sensation’– This is a very striking deep purple cultivar. Flowers get 2-3 inches across and plants grow 12-18 inches tall. Also attracts butterflies.
• ‘Picotee’– Beautiful white blooms are outlined in shades of pink and purple in this cultivar. Plants grow about a foot tall and look great next to darker-colored cultivars.
• ‘Pink Picotee’ or ‘Pastel Mix’– Both of these are a beautiful mix of pink and pastel colors. ‘Pink Picotee’ has shades that range from blush to dark pink. ‘Pastel Mix’ has soft shades of pink, peach, yellow, and white.
• ‘Pastel Lemon’– Another beautiful mix of lemony yellow and tangerine. Plants grow 10-15 inches tall.
• ‘Mirabelle Vert Mix’– This is an incredibly unique mix because all blooms have an emerald green center. Flowers are a range of bright colors like orange, hot pink, yellow, and red.

Where to Buy + Tips

Even though they sound somewhat exotic, ranunculus bulbs are not hard to find. Many large retailers like Home Depot will sell them, and you can even find a pretty good selection of ranunculus bulbs on Amazon.

If you’re looking for a specific cultivar, the best option may be to buy from an online nursery that will ship the bulbs to you in the spring. You can look up the exact cultivar you want and have it sent straight to your door at the right time for planting.

Finding ranunculus bulbs for sale isn’t difficult, but if you’re looking for a specific cultivar, it may be easiest to order online. As a bonus, mail-order nurseries usually ship plants right at the planting time for your region.

Buying a bulk amount of ranunculus will give you a better overall price, but it really depends on how large an area you want to plant.

For the most flowers and vigorous stems, buy large (or jumbo) bulbs. Smaller ones typically send up smaller flowers, which may be a better choice if you want to grow in containers.

A final option is to buy ranunculus seeds, but they can be tricky to grow if you don’t have experience. The seeds also need to be started months ahead of time, so keep that in mind if you choose to buy them.

How to Plant Ranunculus Bulbs

When to Plant

Your planting time will depend on what region you live in.

If you live in zones 8-11, you will need to plant your bulbs in the fall. They will sprout on their own in early spring and bloom for almost two months.

If you live anywhere below zone 8, you’ll need to plant your bulbs in late winter or early spring. If you have space inside, you can start them in pots about 12 weeks before your last frost date. Otherwise, they can go in the ground once the threat of a hard freeze is past.

Spring-planted bulbs will bloom later than fall-planted ones and have a shorter bloom time, but will still be beautiful.

If you aren’t sure what zone you live in, consider whether temperatures drop below 10°F in the winter. This is about the lowest temperature the bulb will survive. Once plants emerge above ground, they need temperatures to stay above 20°F.

Ranunculus bulbs can take freezing temperatures but not a severe frost. There’s a fine line between getting them out early enough in your garden so they will bloom in time and putting them out too early in temperatures they won’t survive.

Where to Plant

Ranunculus can grow in a wide range of growing conditions, but it does need to be in a full sun location. This means an area that gets at least 6 hours of sunlight every day.

Your planting site should have good drainage to ensure that the bulbs don’t rot in overly wet soil. Be sure to amend clay soil before planting, and add in something like compost for better drainage and a good supply of nutrients.

You can choose to plant ranunculus either in the ground or in containers. They won’t grow as large in containers, but you can easily display them when they bloom. You’ll also be able to plant the bulbs sooner if you choose to put them in pots.

If you want a large supply of ranunculus for cut flowers, growing them in the ground is the better choice.

Planting in Containers

If you choose to grow ranunculus in containers, you can get a headstart and plant them indoors, or wait until temperatures have warmed up and plant them outside.

You don’t want to crowd your plants, so only put one or two bulbs in each 10-12 inch pot. If you have very large containers, you’ll be able to plant several ranunculus in each, as long as you can space the bulbs at least 3-4 inches apart.

Make sure your containers have drainage holes in the bottom. If they don’t, drill some yourself to make sure your plants won’t end up in standing water.

Then, fill up your pots with a good quality potting soil. Mix water into the potting soil until it’s damp but not soaking wet.

When you open your package of ranunculus bulbs, you’ll notice that the corms look a little like tiny brown sea creatures with lots of tentacles. This is what they are supposed to look like, but it can be a surprise when you first see them.

Before planting the corms, soak them in room temperature water for 3-4 hours. This will help them get started growing more easily once you plant them. Don’t leave them in the water for longer than 4 hours because the bulbs may start to rot.

After soaking, plant the ranunculus bulbs with the “tentacles” facing down. Space them 3-4 inches apart in the containers and plant them 2-3 inches deep into the potting soil.

Water them well after planting, but don’t water again until they sprout unless the soil completely dries out.

Planting in the Ground

For spring planting, you’ll have to wait a little longer to plant ranunculus in the ground than in pots because it takes the soil outside longer to warm up than soil in containers. If you live in a mild climate, you can plant in the fall without worrying about cold temperatures.

To help your plants catch up, you can do something called presprouting. (Presprouting is only necessary for spring planting. Skip this step if you are planting in the fall.)

If you are lucky enough to live in a mild climate where ranunculus is a perennial, you don’t need to presprout your bulbs. Just soak them 3-4 hours before planting and put them in the ground.

First, soak the corms for 3-4 hours in room temperature water. They should plump up during this process, sometimes doubling in size.

Then, take an open seed tray and fill it halfway with dampened potting soil. Take your corms out of the water they’ve been soaking in and spread them on top of the potting soil in the tray. Cover them with another layer of soil until they are completely covered.

Put your filled tray somewhere that gets a temperature range of 40-50°F, which could be a garage or somewhere similar. Make sure you put it somewhere mice and other critters can’t bother it.

Leave your tray sitting for 10-14 days. During this time you can go ahead and get your planting spot ready by weeding, adding compost if needed, and smoothing out the soil.

Check on your corms every few days and take out any that look moldy. Towards the end of the time period they should have tiny, hair-like rootlets growing out. Once the roots get ¼-½ inch long, they are ready to be planted.

Plant the corms about 2 inches deep with the claws facing down, and space them 6-10 inches apart. Water them in well and watch for them to sprout.

Growing Ranunculus from Seed

Growing ranunculus from seed is not the easiest method, but it can be done if you want to give it a try.

It can be tricky to start and grow ranunculus from seed, but the result will be rewarding if you’re successful. The biggest tip is to keep both seeds and seedlings in cool temperatures as they grow.

For a spring planting, you’ll need to start your seeds in winter. The seeds can take up to a month to germinate and will flower 3-4 months after being sown, so plan accordingly.

Here’s what you’ll need:

• Ranunculus seeds
• Seed starting tray
• Good quality seed starting mix
• 3-4 inch plastic pots
• Grow lights or sunny windowsill
• Plastic domes (optional)

Fill your tray or trays with damp seed starting mix. Sow the ranunculus seeds on top of the soil, and press them in but do not cover them. Water them gently and cover with plastic domes if you have them to keep moisture in.

Place the trays under grow lights or in indirect sunlight. The seeds need light to germinate as well as temperatures between 50-60°F. Make sure you give them both of these, and germination should take 14-28 days. Make sure the soil stays moist throughout this time.

Once the seeds germinate, remove the plastic covers if you had them on. Keep your plants by a sunny window or under grow lights as they grow.

The key for ranunculus seedlings is giving them temperatures around 60°F during the day and around 40°F at night. Mimic these conditions as closely as you can, and water your plants as needed.

Your plants will flower about 3-4 months after you start them from seed, and seeds can take two weeks to a month to germinate. This means you’ll need to start your seeds in mid to late winter for spring planting.

Once seedlings have 4-5 sets of true leaves, transplant them to individual plastic pots filled with a good quality potting soil. Let them grow in these pots until temperatures have warmed outside in the spring.

You can then gradually harden your plants off and plant them in the ground or in containers.

Ranunculus Care

It’s important to keep your plants well-watered as they grow, especially if they are in containers, but don’t let the soil get soggy.

If you’ve planted your ranunculus outside in the spring, it’s a good idea to have sheets or row covers close at hand to cover your plants in the case of an unexpected freeze. Containers can be brought inside if temperatures dip below freezing.

Because ranunculus does best with cool roots, putting mulch around your plants can be beneficial. However, make sure you leave a few inches between the mulch and the stem of your plants to prevent rot from occurring.

Ranunculus will typically bloom around 90 days after being planted. This is usually early spring for fall-planted bulbs and mid to late spring for winter- or spring-planting bulbs.

The blooms will continue for four to seven weeks. Plants will benefit from deadheading, and this may extend the blooming season, but it’s also optional. Another good way to keep your plants flowering for longer is to cut blossoms regularly to use as cut flowers.

Thankfully, ranunculus is a very easy plant to take care of once it has been successfully planted in your garden. It rarely suffers from pests or diseases and only needs an occasional deadheading.

If you are growing ranunculus as an annual, there’s no need to fertilize. If you are able to grow it as a perennial, a yearly application of compost or a balanced fertilizer should be adequate.

When the foliage dies in the summer, you can cut it off at ground level to tidy up.

Overwintering Your Bulbs

If you live in zones 8-11, all you need to do is cut the foliage back when it dies and allow your plants to come back the following spring.

If you live in a colder zone, there are two options for handling your ranunculus bulbs.

Your first option is to dig up the bulbs before a hard freeze comes in winter. You can dig them up and store them much like you would dahlia bulbs, but ranunculus are notorious for not storing well, and they may not last until next spring.

Because of storage difficulties and the inexpensive nature of ranunculus bulbs, most gardeners choose to simply compost the bulbs at the end of the season and buy new ones the following spring.

The choice is yours!

Don’t forget to cut some of your beautiful flowers to put in a vase or floral arrangement. Cut them before the buds open but after they have fully colored.

Pests and Problems

Ranunculus is not prone to many pests or diseases. There is a possibility that rodents and other small animals may dig up the bulbs when you plant them, so keep an eye out for this. Start them indoors in containers if this becomes a problem.

Occasionally, ranunculus will be bothered by minor pests like aphids. A hard spray of water or a natural insecticidal soap can take care of them.

As far as diseases, ranunculus is most likely to get a fungal disease like powdery mildew or root rot. Both of these come from overly damp conditions, so spacing your plants properly and avoiding soggy soil is key.

Companion Plants and Cut Flower Bouquets

Ranunculus bulbs can be planted in masses for a beautiful effect in your garden. They also work well with other spring and summer flowers like pansies, daffodils, peonies, snapdragons, and various other spring bulbs.

To harvest ranunculus for cut flowers, wait until the buds have colored and are squishy like a marshmallow. Cut off flowers and stems before the buds open and arrange them in a vase.

Though it takes a bit of work to learn how to grow ranunculus bulbs, the beautiful display and cut flowers you end up with will be well worth it!