By Stephanie, West Seattle Flower Farm | Last updated October 2026
Short answer: In Seattle, you can plant ranunculus corms from September through early March. Soak them for three to four hours first, then plant them straight into the ground, or presprout them indoors for about two weeks if you want a head start.
How I know: I’ve grown ranunculus in my West Seattle backyard for a few years now, with plenty of successes and failures. The full story, mistakes included, is below.
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Ranunculus is a cannot-miss spring flower.
They have incredible vase life, resemble a peony or a rose with their countless petals, and can bloom throughout spring.
Ranunculus require more fussing than tulips or daffodils, but when they bloom it’s spectacular. Plus, they will likely bloom multiple times in the spring, meaning you’ll get waves of flowers rather than a one-and-done, like a tulip.
I’ve been growing them for a few years now and I have had successes and failures.
Despite the failures, I’m hooked.
Here’s how I grow ranunculus in Seattle (zone 8b/9a):
When to plant:
In Seattle, you can plant ranunculus corms from September through early March. Last year, I planted my first wave of ranunculus in October. This year, I’m testing a September start. I’ll add those results here next year and let you know if they bloom earlier.
Ranunculus benefit from cold stratification—which means they grow better when they experience several weeks of cool weather before blooming. The earlier you plant them, the earlier they bloom and the more they’ll bloom during the spring.
They can survive temps down to 25 degrees for short periods. Fortunately, Seattle winters rarely get that cold, and when they do, it’s brief. Since the ground almost-never freezes, you can plant them and let them do their thing.
I use row cover and leaves/mulch for extra warmth when temps drop below freezing for extended periods. If ranunculus corms are exposed to prolonged freezing temps, they’ll freeze and rot.
Last season, I planted ranunculus in waves from October through January, hoping for flowers all spring. It worked, and I wrote about when each wave bloomed in When Do Ranunculus Bloom in Seattle?
When you buy corms, you’re purchasing dehydrated roots (they look like calamari) that need to be soaked before planting.
If possible, buy the largest corms you can. Bigger corms = more blooms and better rot resistance.
There are many varieties of ranunculus in different shapes and colors. More expensive corms are larger, produce more blooms, and are more disease-resistant. But cheaper varieties grow great, too.
Soaking (recommended):
Soak your corms in room temperature water for 3 to 4 hours. Don’t over-soak or they’ll rot.
This hydrates the corms and helps them germinate faster and more reliably.
I set a timer for three hours, knowing full well I’ll lollygag before actually pulling them out and getting them into dirt.
I do NOT change the water every hour or keep it flowing with a sous vide or aquarium pump like some people on the Internet claim you need to. Life is too short. My husband would also kill me if I used our sous vide in the kitchen for gardening. (He instituted a strict no-kitchen-items-shall-be-co-mingled-with-anything-gardening-related policy after past incidents.)
Presprouting (optional):
I used to presprout all of my ranunculus indoors because I was paranoid about rot and rats. After a season of testing, I recommend planting straight into the ground by default. I still presprout, but only if the space where I want to plant the corms isn't ready yet. (Here's what I mean: I often plant ranunculus where I have dahlias growing, so if I am not ready to dig and divide dahlia tubers yet, I will presprout ranunculus; then over the next two weeks, I will dig and divide the dahlias and replace them with ranunculus.
One year, I tried direct planting a batch of corms and presprouting another batch. They both ended up blooming at the same time.
Here’s how to Presprout:
Fill a flat-bottom seed tray (plastic fruit packaging or reusable takeout containers work too) with fresh potting soil (never reused)—about half an inch to an inch deep.
If the potting soil comes out of the bag moist, I put the corms right in. If it’s dry, I use the hose to get the soil wet.
Place the ranunculus corms on the soil, tentacles down, then completely cover them with more soil—an inch or two is sufficient.
Put them in a room that’s between 50 and 65 degrees for about two weeks. (If it's a little colder or a little warmer, they'll be fine.)
Check on them at least once a week to make sure the soil stays consistently wet and none of the corms are rotting. Dry soil and reused soil are what rotted my corms, so use fresh soil and a clean tray every time. More in How Not to Kill Your Ranunculus.
When the corms sprout white roots after two weeks, they’re ready for planting.
A presprouted ranunculus corm
Do you need to presprout?
No. Soak the corms and plant them straight into the ground, as long as no freeze is forecast. If rats are a problem in your yard, presprouting indoors keeps the corms out of reach until they have roots.
If you don’t presprout, plant your corms immediately after soaking them for a few hours.
Ready to get your own corms in the ground?
Tips for planting ranunculus
- Plant them with the tentacles down.
- Plant them inches apart (I always plant 6 inches apart) and 1-to-2 inches under the surface.
- Add compost and a well-balanced fertilizer when planting. (I top off my growing area with an inch or two of Cedar Grow compost from Burien Bark, and mix in a well-balanced fertilizer when I plant.)
- Low row cover is a nice extra, not a requirement. I use it for wind protection, a few degrees of warmth, and keeping cats out, and I add it when several days of below-freezing temperatures are forecast. Read more about it here.
End of season ranunculus care
Ranunculus corms go dormant when the weather gets too hot, which happens in Seattle around June.
If you want to dig them up and store them to replant next season, wait for the foliage to naturally die back. Then dig them up, dry them, and store them in a dark, cool area until you’re ready to replant.
Better yet: In the Seattle area, you can just leave them in the ground and never dig them up. This year, the corms I left in the ground started sprouting new foliage in late September, so I know it can work in Seattle. Ranunculus' return isn’t guaranteed, but if you see them sprouting in September or October, you know they've made it.
Saving corms for the following year
You can treat ranunculus corms as annuals or plant new ones every year. If you decide to dig them up over summer (so you can plant dahlias or other summer annuals in their place), let the plant finish blooming until the foliage starts to die back. Then dig them up, let them dry out in a box, and store them in the garage until you are ready to plant them again.
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