How to Grow Ranunculus: A Flower Farmer’s Secret
If there’s one flower that can stop people in their tracks, it’s ranunculus. These cool-season beauties bring early spring magic with their layers of delicate petals and long vase life, making them a favourite in our flower bouquets and markets.
More and more home gardeners are falling in love with them—and understandably want to grow them, too. But... they can be a bit tricky to grow.
We know because we’ve been there! We’re happy to share what we’ve learned to help you get it right.
WHAT RANUNCULUS NEED TO THRIVE (And why they can be so tricky!)
Ranunculus have a reputation for being fussy, but the truth is, most gardeners just aren’t given the right information to begin with.
This is it right here, folks… Ranunculus are a cool-season flower! They thrive in early spring temperatures. And while they can tolerate a light frost (minus 2- 3 °C), they don't appreciate a heavy freeze. And this is what makes them especially tricky. They have a bit of a Goldilocks complex.
Many garden centers offer corms at the wrong time of year, which makes it tough to get them off to a good start. If you’ve tried and ended up with disappointing results, you’re not alone!
Each spring, we meet customers who are amazed to see our ranunculus blooming in May, while theirs are just going into the ground. But here’s the truth:
👉 If ours are blooming, yours should already be planted.
But don’t worry—we’re here to help you get it right next time!
HERE'S WHAT YOU NEED TO KNOW:
- Ideal growing temperature: 10–15°C (50–59°F)
- Keep the roots cool: Below 13°C (55°F)
- They’re heat sensitive: (Did I mention that they like it cool?!) Plants will stop blooming and begin to go dormant and die back when temperatures regularly exceed 20°C (64–68°F)
- Days to bloom: about 90+ days from planting
🌱 Timing is everything. If you want blooms in May, you need to start your corms in late winter
Step 1: Soak and Pre-Sprout Your Ranunculus Corms
Pre-sprouting gives your ranunculus a head start and reduces failure. This shows what freshly soaked corms look like.
- Soak corms in cool water for 4 hours. Use a mason jar and either run a slow trickle of water or change it out several times.
- Prepare a tray or deep 6-packs with moistened (not soggy!) potting mix.
- Plant corms “fingers down,” cover with 1" of moist soil.
- Keep trays cool (10°C / 54–57°F) for 10–14 days while roots form and sprouts emerge.
- Once sprouted, move them to a bright area. We place ours under LED grow lights, suspended a few inches above the leaves, to help avoid leggy growth.
- Continue growing indoors for 4–6 weeks at around 10-15°C (59°F).
Corms planted into deep 6-packs, ready to be covered with soil and set in a cool spot.
Step 2: Planting Ranunculus Outdoors
Ranunculus are tough enough for light frosts but should be protected from a hard freeze. Early April is ideal in zones 5–6.
- Harden off your plants for a few days by slowly introducing them to the outside elements.
- Choose a sunny spot with good drainage. Amend your soil with organic fertilizer.
- Plant just below the soil surface, spacing 6–8 inches apart.
- Water in, and keep an eye on temperature swings.
Step 3: Caring for Ranunculus as They Grow
Once they’re in the ground, consistency is key:
- Water regularly—the soil should stay evenly moist but never soggy.
- Protect from a hard freeze. They can tolerate a light frost (minus 2- 3 °C), but keep a frost blanket handy for anything colder.
- Protect from heat if necessary, with early morning watering or temporary shade tunnels.
- Enjoy the show! With the right care, blooms will begin 2 months (ish) after planting.
HerH
Here you can see ranunculus with hoops over top and shade cloth on the adjacent row (we removed it from this row to harvest the flowers).
Tips for Success
- Ranunculus are spring bloomers, not summer stars. Plan accordingly.
- While they don’t love a hard freeze, they can survive it, especially before flowering when the plants are small. Be prepared with a frost blanket. We’ve had ours survive minus 20°C!! We used a double layer of frost blanket and a layer of plastic. I wouldn’t say they loved it, but they survived!
- Prepare for a heat wave with shade cloth and something to suspend it over your plants (like hoops made from wire or plastic pipe). A hot day here or there won’t do much harm, but an extended heat wave can force them to flower on short stems and go dormant.
- Ranunculus are excellent cut flowers—harvest in the cool of the day when the flowers have opened.
You Can Do This!
Growing ranunculus isn’t as hard as it seems; it just requires the right timing and a bit of planning.
Let me know if you have any questions. Happy planting!
Sarah
