Ranunculus plants are descended from the wildflowers, commonly known as buttercups.
Calling these ornamental flowering plants beautiful is an understatement. Have you seen their gorgeous, double-petalled blooms?
However, it’s important to ask: “Are Ranunculus hardy?” if you want to try cultivating them.
The Ranunculus plants are half-hardy, which means they can tolerate winter temperatures above 25℉. They are cool-season spring flowers that thrive at temperatures between 55 and 60℉.
To learn more about how hardy Ranunculus plants are and how to take care of them during winters, keep reading!
What Does It Mean to Be Hardy?
Hardiness is a term used to describe the plant’s ability to withstand adverse climatic conditions, especially cold and frost. Plants are either hardy or tender, with terms like “half-hardy” used as a midway between the two.
Hardy plants can either survive the cold and go dormant or thrive in the winter and reach their full potential. Tender plants, on the other hand, can’t maintain their vital processes during winter and will die if faced with freezing temperatures.
Are Ranunculus Hardy?
The scientific name for Persian buttercups, Ranunculus asiaticus, lets you in on where they originated. They grow as wildflowers in the Eastern Mediterranean basin. During their bloom season, you can spot them as delicate, single-petalled buttercups.
After many rounds of hybridization, the gorgeously colorful and double-petaled Ranunculus cultivars were born.
Whether straight or ruffle-petaled, you can’t help but wonder how such delicate creatures can survive cold, harsh winters.
In US hardiness zones 8–10, where temperatures don’t drop below the 25℉ threshold, they are winter hardy and can be treated as perennials. However, those who live in zones colder than zone 7 mostly treat Ranunculus as an annual plant.
Aside from the frost and high wind that can damage the foliage and flowers, freezing soil temperatures damage Ranunculus corms.
Corms, also known as bulbs, are energy storage organs that sprout into the root and shoot systems when planted into the soil.
Corms can be quite fragile and will die if the soil temperature drops. They are also sensitive to soil moisture. If frozen ground thaws, the stagnant water surrounds the corm, and it will rot and die.
This is to say that the Ranunculus will tolerate some but not all winter conditions. So it’s up to you to figure out whether to treat your Ranunculus as an annual or a perennial based on the temperature in your area.
Ranunculus as an Annual Plant
If you live in US hardiness zones 4–7, there’s a big chance you’re familiar with annual plants that you have to bring in every year. The Ranunculus is a great option for a late spring/early summer bloom to add to your garden if you live in these areas.
Let’s go through the steps you need to take to have a successful Ranunculus yield in your zone.
This step can be a bit complex. If you’re planting from corms, you should pre-soak and sprout them in a planting tray. However, if you prefer seeds, sprout them in a flowerpot until four true leaves grow from the seedling.
To have your flowers ready in the spring, you should start the corms around early March and the seeds in late January. Both methods have to be done indoors, at a temperature of about 50–55℉. Give your seedlings at least 6 hours of light every day to strengthen their stems.
Once the last frost has passed, usually around mid-April, you can take your seedlings outside if you’re planting a cutting garden or a flower border. You can mitigate the cold nights by either getting a hoop (high-tunnel greenhouse), covering your plants with frost cloth, or both.
For those who want to plant a smaller volume, containers can be a great option. You can take them out during the day to make sure that your Ranunculus has enough sunlight. Once it’s dark out, just put them back inside. This way, they’re protected from the cold night temperatures.
- Overwintering (Optional)
Your Ranunculus will bloom for about 4–7 weeks, depending on when you started them in the late winter/spring. After the flowers fade, deadhead, dry, and save them to get seeds for the following season.
You can also save the corms if you prefer. Just let the foliage wither and yellow, then trim it once the plant is dormant. Dig out the corms and let them dry in sand or another dry medium, like peat moss.
Once you’re done, you can store them in a box or a paper bag and take them out the following year to repeat the process.
It’s important to know that this process doesn’t always work. Sometimes, the corms rot in the ground. Other times, small animals like squirrels and voles dig them out before you get to them. It’s also not a hundred percent guaranteed the corms will be revivable the following spring.
Ranunculus as a Perennial Plants
Those who live in US hardiness zones 8–10 can enjoy their Ranunculus as perennials with a lifespan of up to 10 whole years!
However, they still require some care and disease prevention to get it to life even half that much.
The steps for Ranunculus care as a perennial are a bit different since you can just leave them in the ground year-round. You can add a few steps to ensure they’re thriving and giving you the best they’ve got.
This step is pretty simple and straightforward. Get your corms (or seeds) from a good-quality, reputable, and preferably local vendor.
Seeds are best started between September and December, and corms can be sprouted as early as December to get your Ranunculus by early spring.
Till the soil and mix it with compost in your garden, or use a seed-growing mix if you’re planting your Ranunculus in a container indoors.
Make sure your growing seeds are getting plenty of sunlight. However, those who live in the hottest zones should be careful with sun exposure. Partial shade is preferred during the hottest hours of the day.
If you sprout your seeds in a tray/flowerpot, transplant them after 4–6 weeks or after four true leaves have grown.
Take your time spreading them around your garden, spacing them at least 6 inches apart to allow lateral root growth. This is especially important since you won’t dig the corms out very often.
On the other hand, container-grown Ranunculus is a great indoor plant. Just make sure you’re adequately spacing the seedlings since it’s easier to transplant them when they’re small rather than fully grown.
- Division and Propagation (Optional)
Propagating your Ranunculus by dividing the corms is beneficial to the plant. As a plus, it’s a great way of getting more beautiful blooms.
If left in the ground for too long, corms begin to grow offsets or smaller corms. Since they’re attached to the original corms, they can cause the plants to be rootbound.
To avoid the adverse effects of root-binding, which can stunt the growth and flowering of your Ranunculus, divide them every 2–3 years.
All you have to do is wait for the leaves to die back in the fall, trim them, and dig out the corms. With a sharp knife, separate the corm from the offsets, and plant them in the ground right away.
This will also further prolong the life of your Ranunculus plant and bring even more beauty into your garden.
For those wondering “Are Ranunculus hardy?” because they’re hesitant about introducing them to their gardens, go ahead and do it!
Ranunculus can take temperatures as low as 25℉. Even in the coldest zones, you can still overwinter your corms and replant them the following season.
Just make sure to start your Ranunculus plants at the right time for your hardiness zone, and keep an eye out for their sun and moisture exposure.
With proper care and attention, you can enjoy “the rose of the spring” for months and months!
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