How to Grow and Care for Ranunculus

Ranunculus flowers had me besotted long before I ever started a garden. Originally, I was drawn to the layers upon layers of delicate, tissue-paper petals. In my eyes, ranunculus flowers were just utterly romantic! Eventually, as I learned how to grow ranunculus in my own garden, I started to appreciate these stunning flowers for a long list of other attributes—like their ability to bring color to the early spring garden and their impressive vase life. For us gardeners, ranunculus are very rewarding blooms!

Ranunculus are one of the best cut flowers you can grow for Spring. While I’ve written briefly about ranunculus, in tandem with two other incredible spring cut flowers (daffodils and anemones), this will be my first post dedicated to sharing my experiences growing ranunculus here in Southern California. 

Growing Ranunculus From Corms

These incredibly beautiful flowers grow from corms, which are surprisingly unattractive. In fact, one time I posted the corms on my Instagram, and tons of people commented that they thought the corms were cockroaches! I can’t unsee it now. Corms are essentially swollen stem parts that can store energy for the plant, much like dahlia tubers or spring bulbs.

Over the years I have sourced my corms from a myriad of places. To start, I got most of my corms from Easy to Grow Bulbs. Also, local nurseries sell ranunculus potted up in Spring, and I’ve been known to snag colors that speak to me. Recently, I ordered some specialty colors from Eden Brothers and have been happy with the blooms. I’ll talk about this further below, but I have been slowly curating the ranunculus color palette in my small garden. Since I have to be wary of space, it’s very important to me to save only the most vigorous corms and the colors that work well for me.

Can I grow ranunculus from seeds? Yes! While I highly recommend growing ranunculus from corms for consistency and dependable results, it can be fun to venture out and experiment with how to grow ranunculus flowers from seed.  Lucky for you, I’ve got a whole post about how to collect, save, and grow ranunculus flowers from seed.

Garden Conditions for Growing Ranunculus

Does it surprise you that we can grow amazing ranunculus flowers in Southern California? The sheer number of delicate petals on this flower can make it look finicky to grow, but we actually live just a couple hours from one of the most notable ranunculus fields in the country. The Carlsbad Flower Fields are home to around 55 acres of ranunculus flowers.  They open to the public every Spring (around March to early May) and visitors can walk on paths around the fields to admire the rows upon rows of brilliant ranunculus blooms. Surprisingly, I’ve never made the trip to the Carlsbad Flower Fields. The ranunculus bloom for a short 6-8 week period in Spring, which happens to always coincide with lots of life events, and also the busiest time in my own backyard garden. Maybe one day!

In the garden, I have experience growing ranunculus flowers both in-ground and in raised beds. From experience, I noticed that the raised bed ranunculus tend to grow more robust, which I assume is due to “ideal conditions” like rich, healthy, well-draining soil. Alternatively, I notice that the more I nurture my in-ground soil with compost each season, the happier those ranunculus are! In the end, both locations are fine for growing ranunculus flowers as long as you continue to nourish the soil with organic matter and compost so the soil is rich and won’t be water-logged.

There are lots of different types of ranunculus. For example, the Flower Fields grow Giant Tecolote ranunculus (a fellow gardener once bought me some corms from their gift shop). So, as you’re learning how to grow ranunculus in your own garden, be aware that some might perform better than others. In general, ranunculus will bloom the best in full sun (at least 6-8 hours of sunlight) and when the weather is not too hot, yet not too cold. Ranunculus prefers mild temperatures between 55 and 70 for optimal growth and bloom—which brings me to specific gardening tips for growing ranunculus in mild winter (yet extremely hot summer) climates like Southern California.

When to Plant Ranunculus Corms 

As many of you know, Spring in zone 10 can be fleeting and suddenly jump to Summer temperatures on a whim. This is why we should take advantage of Fall planting to encourage good root establishment and an earlier Spring bloom. In my area of Southern California, we don’t get colder than 30 degrees typically, and I have never lost a ranunculus plant to frost or even frost damage This tells me that the plants can survive at least down to 30 degrees F, but probably down to 25 degrees. Ideally, gardeners in zones where it doesn’t get much colder can benefit from planting ranunculus in Fall . On the other hand, I’ve seen gardeners in zones 7 and 8 plant ranunculus in Fall using tunnels or frost cloth to protect from colder temperatures through Winter. Here in Southern California I tend to aim for planting ranunculus at the end of October, or early November. 

If you are growing in a colder zone, you can use the “pre-sprouting method” to grow ranunculus flowers. This method entails soaking your corms in water, and planting in trays indoors so that you have a head start on the growth before planting out in Late Winter or Early Spring. Since I do not have experience with this method, I would suggest doing research on local gardeners and their pre-sprouting practices.  

Aside from Fall planting, us mild Winter gardeners might be able to squeeze out some plantings of ranunculus corms all the way from Fall through Late Winter. Again, ranunculus aren’t going to grow well for you once it gets too hot, so your ideal planting window is going to depend on how long our Spring temperatures last. The number one reason for a short and sad ranunculus season is planting too late for your zone!

Why I soak Ranunculus Corms

If you do some research on how to grow ranunculus, you might come across the topic of soaking. To soak or not to soak? Like many things in the garden, there’s no single “right way” to do something. I’ve both soaked and not-soaked my ranunculus corms before planting and did not notice any decipherable difference in performance. Regardless, I have decided that I have a personal preference—-soaking! Here’s why:

I prefer to soak my ranunculus corms before planting because I feel that it makes them less prone to snapping or breaking. Personally, the dried corms feel very fragile to me, and I’ve lost pieces of the corms before due to handling. On the other hand, after a brief soaking, the ranunculus corms are plump and seemingly easier to handle without breaking. To soak ranunculus, simply place the corms in water in containers and plant them when plumped up. This process can take anywhere from 2-4 hours. It’s better to under-soak than over-soak, so as soon as the corms look plump you are ready to plant!

Planting Ranunculus Corms in the Garden

Before planting your ranunculus, make sure to amend your garden with a few inches of compost and an organic flower and bulb fertilizer. Honestly, this is all the amending I do, and the flowers have a great bloom all season without needing any more fertilizer. If, for some reason, your plants start to look more yellow and less green, you can feed the plants with a fish or kelp fertilizer. Sometimes raised beds lose a lot of nutrients during the rainy season here, so it’s not abnormal to feed your plants a bit to see if they green back up.

In my ranunculus growing video, you’ll see me planting the soaked ranunculus corms in a raised bed with a garden grid. One benefit of gardening with the garden grids is that they make watering easy, but they also make spacing easy. In general, about four ranunculus corms will fit in one square—I try and keep at least 6 inches between plants.

To plant the corms, hold them like an octopus (the “legs” dangling downwards) and place them in a hole about 2-3 inches deep. Cover gently with soil, and water if your soil is not moist. Usually, there is rain incoming during ranunculus planting season here in Southern California, so I tend to not water after planting. Also, ranunculus corms are susceptible to rot, so keep watering to a minimum until you see some sprouts!

Protecting Ranunculus From Pests or Critters

Most of the pest problems I have with ranunculus happen right after planting. Critters like squirrels or raccons can dig up the corms. We are fortunate in that we don’t deal with gophers or other underground type critters in our backyard.

In order to keep my corms (or really, any tubers or bulbs) protected, I will often cover my newly planted bed with a wire grid and sometimes DIY row covers. Essentially, I find that most of the time the animals just want “easy” food, so any type of cover has a chance at deterring them. In fact, if you want to see the wire grid, it’s very much the same type of grid I put down for the asparagus bed I planted last year.

How to Harvest & Pick Ranunculus at the Right Time

I only have 12 square feet dedicated to ranunculus in my garden, and I have more than enough blooms! Ranunculus are incredibly generous cut flowers, but it’s important to harvest them at the right time for a couple reasons. First, cutting the ranunculus stems will encourage more stems and buds to pop up throughout the season. Remember, they will continue to bloom as long as the weather cooperates. Once it starts to get too hot, the plants will slow down. Second, knowing when and at what stage to harvest ranunculus flowers will increase the amount of vase-life you get.

Ideally, you want to harvest ranunculus flowers when the buds are no longer tight with their green sepals covering them. The buds eventually start to open up, and I learned from Floret that this is called the “marshmallow” stage. Literally, if you squeeze the ranunculus heads with your fingers they feel like squishy marshmallows! Picking ranunculus flowers at the marshmallow stage can give you a vase life as long as 10-12 days, but don’t stress too much about it. If you wait longer to pick your ranunculus, they still have a remarkably long vase life compared to a lot of other flowers.

Finally, when you go to cut the stems of your ranunculus, make sure you chase the stem all the way to the ground to make the cut. Yes, this does sacrifice side buds, but it’s much better for the plant and will encourage future stems to emerge.

Overwintering Ranunculus Flowers in Mild Climates

Is overwintering the right term? Technically we are oversummering and overwintering, right? Whatever the technical term is, you can absolutely leave your ranunculus corms in the ground after the season, and they will re-sprout the next Spring. I wish I could say that there’s some secret to doing it right, but I really just leave them and that’s it. Now, in zones that get colder, this isn’t possible. Ranunculus corms are very prone to freezing and they will rot once they defrost. Because of that, many cold climate gardeners treat ranunculus flowers as annuals and just buy new corms every year. Or, they can dig up the corms and save them in storage.

Digging & Storing Ranunculus Corms

Now, I don’t always leave my corms in the ground due to limited space in my garden. Sometimes, I dig up my corms to store for the following season and make room for other crops. Admittedly, digging and storing corms, tubers, or bulbs always comes with some amount of risk, but I’ve stored ranunculus corms successfully and will happily share how I did it.

If you want to save and store your ranunculus corms, you need to let them die back in the garden. The stems and leaves will start to yellow and die. At this point, I pull the plants carefully out of the ground (or dig them up with a garden fork) but leave everything intact.

Take your bundles of plants and lay them in a dark and dry place, like a garage, to completely dry out. Of course, we want dried but not withered. Once everything seems completely dry, you can snip off the stems and collect your corms in a paper bag. My paper bag of corms went into a bedroom closet and stayed nice and dry until Fall planting time!

Does that sound too easy? After hearing how difficult dahlia tubers can be in storage, I was honestly surprised how simple it was to keep the ranunculus corms successfully.

How to grow ranunculus with long stems

I have gotten questions about how to grow ranunculus flowers with long stems for cutting. In my experience, ranunculus stems grow plenty long for bouquets if they are happy. This means good soil, plenty of sun, adequate space, proper weather, etc. Like many other plants, ranunculus can be stunted or less robust if there is something wrong with their growing conditions. In the end, there is nothing specifically that I do to get longer stems on my ranunculus—but this is why timing the planting can be the difference between a wonderful harvest and a short and sad one.

How do Ranunculus Multiply?

I’ve got great news for you! Ranunculus can multiply and increase the number of corms you have each year. When you go to dig up your ranunculus corms at the end of the growing season, you might see that the corms look more clump-like. In actuality, there could multiple corms stuck together in that clump, because that is how ranunculus flowers spread. If you see this, you can actually pull apart the corms and now you’ll have more plants!

Growing The Perfect Ranunculus Palette in Your Garden

The journey to growing my very best ranunculus didn’t happen overnight. In fact, I had one disastrous Summer when I chose a terrible garden bed, surrounded by large stones, that basically burnt all my corms and tubers! Furthermore, it took me time to figure out the colors of ranunculus I liked together. One thing I have been doing to “curate” my ranunculus collection is to save only the corms from plants that were robust, healthy, and the perfect colors! Here’s the thing, no vendor is perfect. I occasionally will get an odd color thrown into an order, or one of the corms just isn’t growing well, and so I either pull it right away or make a note to toss it at the end of the season.

Currently, I can see that I’m missing darker purples, deeper reds, and oranges, so those will be the colors I plan to order for next season. In my opinion, it’s nice to take photos each season and see what colors you might want in the future.

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