How to Grow Ranunculus for Cut Flowers
Ranunculus are gorgeous spring flowers that resemble a rose, but are far more beautiful (in my opinion). Their blooms are absolute show stoppers in spring bouquets. So let’s learn how to grow ranunculus for this year’s cut flower garden!
The best way to grow ranunculus (zone 6 and colder) is by pre-sprouting the corms and then planting them in the garden 4 weeks before your last frost. It’s easier than you think. I promise.
How Do Ranunculus Grow?
There are loads of flowers that grow by seed. Other flowers, like dahlias, grow from tubers. Ranunculus grow yet a different way – – from corms.
Ranunculus corms look like shriveled up tiny octopus or weird tiny claws. If you didn’t know what you were looking at chances are you’d throw it away. Ranunculus corms don’t look very promising! But they are incredible!
When to Start Pre-sprouting Ranunculus
I think this was what was most confusing to me when I started to grow Ranunculus.
You’ll want to start the pre-sprouting process about 6-7 weeks before your last frost. Check here for your last frost date (I like to add 2 weeks to that date). Once you have your last frost date, count back 6 – 7 weeks. This date (6-7 weeks before your last frost) is generally when you’ll want to start pre-sprouting your corms.
If that sounds confusing, here’s my timeline…I live in Pittsburgh, PA, zone 6. My last frost is May 15. Technically I should start to pre-sprout my corms at the end of March.
This year, though, I’m starting at the beginning of March. I have found that once June hits, the sun and heat are so intense my plants die back immediately. That only gives me about 2 weeks of flowers. So this year I’m starting half of my corms 10 weeks before my last frost, and the other half 7 weeks before my last frost, and I’ll get a better idea of what works best in my area.
Unfortunately there isn’t always 1 good answer for when you should start your Ranunculus corms. But 6-7 weeks is a good estimation.
Pre-sprouting Ranunculus Corms
This sounds intense, but it’s really quite simple.
Ranunculus are stored dry. As a result, we have to re-hydrate them to start the growing process. To do this, we soak the corms in a bowl of water for 3-4 hours. But, we have to change the water about every 30 – 60 minutes.
Step 1: Soak
Soak the ranunculus corms for 3-4 hours, and change the water every 30-60 minutes. Don’t go over 4 hours! The corms could rot and die.
I put the corms in a bowl and fill it with room temperature water. Every 30 minutes – 45 minutes I dump out the water and fill the container with new water.
After 3 hours, you should see plump versions of the previously shriveled up corms.
Step 2: “Plant”
Now it’s time to “plant”.
Take a water tight tray and fill it with lightly moistened potting mix or seed starting mix. Either works fine here.
I like to pour boiling water over my seed starting mix to kill fungus gnat eggs. I then let it cool down overnight, and the next day I fill my tray.
Fill the tray about 1″ high with your mix and gently firm it in. Then take the plump ranunculus corms and place them on the mix with the pointy sides down. You can have them almost touching as they won’t be in here for long.
Next, add more potting mix to the top so the corms are completely covered with soil. It should only take about 1″ of soil.
Step 3: Cool and Dark for 14 Days
The ideal place for ranunculus corms to pre-sprout is in a cool, dark, and dry location. Unheated basements (FYI rodents are said to eat corms) are ideal.
You are looking for a location that isn’t too hot or too cold.
I keep my corms on the floor of my basement. My basement is finished and kept at 68 like the rest of the house. However the floor is concrete with laminate flooring, so it’s cold to the touch. I place the tray on the floor with another black seed tray over top of it. This helps to keep it dark, too (we have windows and use our basement quite a bit so it’s not dark).
You shouldn’t have to water your corms unless they look very dry. The pre-moistened soil should be enough to last the 2 week period of pre-sprouting. Check on the corms, and if you see mold or rot, remove that corm and some surrounding mix so the mold doesn’t spread.
Where to Plant and Grow Ranunculus for a Cut Flower Garden
After the 14 days, you should see tiny bumps towards the tops of the corms and white sprouts coming out the bottom. It’s time to plant!
Ranunculus get planted 2″ – 3″ deep and the recommended spacing from growers is 9″ apart. I plant mine 6″ apart.
Ranunculus grow best in cool weather, but they aren’t frost hardy. You need to be prepared to cover these with floating row cover or frost cloth when the temperatures dip below freezing.
I find it best to grow ranunculus in a raised bed with a hoops and frost cloth. This will be my 3rd year using these hoops and I’m very happy with them (they break down into small pieces and store in a small box).
I have the hoops set up first and then plant my pre-sprouted ranunculus. I then cover the hoops with the fabric and secure it with the provided clamps. On warm sunny days, I lift the fabric up so the plants can get maximum sun and wind exposure, and then I lower the sides again at night.
You don’t need to grow in a raised bed with hoops, but you absolutely need floating row covers at the very least for those nights that dip below freezing.
I realize this sounds like a bit of a chore, but for me, I’m so desperate to be gardening again (winter is soooo long) that by March I’m thrilled to get outside on any day over 32 degrees.
If this sounds like torture to you, then I wouldn’t start pre-sprouting until 4 weeks before your last frost. Then you can plant out 2 weeks before your last frost and hopefully you’ll only have to cover your ranunculus once or twice before the threat of frost is gone.
Don’t let covering these plants stop you from growing them! When all the gardens around you are just starting their summer annuals like zinnias, you will already have gorgeous flowers ready to be cut for bouquets.
Grow Ranunculus for Your Own Cut Flower Garden
I’ve seen gorgeous ranunculus plants at Lowes and Home Depot. And while they are beautiful, you can save so much money by growing your own.
I love quantity when it comes to cut flowers. I don’t want 1 ranunculus plant, I want 50. Is it overkill? Probably. But right around Mother’s Day, all the way through October, I have bouquets of fresh flowers in my house. And I take a bouquet to every party I attend. By July I have 3 bouquets in my house and I’m giving some away, too.
If you love the idea of a cut flower garden, I suggest adding ranunculus to your list of must-grow spring flowers.
They take a bit more time than flowers grown from seed, but they are completely worth it.
On a total side note, I’ve seed ranunculus listed as deer resistant. I have not found that to be the case. The first year I grew them in my landscape and the plants never grew bigger than about 4″. The heads were always bitten off. You may have a different experience, but I want to mention it for anyone who has heavy deer pressure.
I’d love to know your thoughts on growing ranunculus. Do you think you’ll give this magnificent spring flower a try? Let me know in the comments below.
Thanks for stopping by!
