In Seattle (USDA zones 8b and 9a), you can plant ranunculus corms from September through early March. Earlier plantings grow bigger and bloom sooner, while later ones stay compact and bloom later. I've planted from October through February with good results, and I'm testing a September start this year.

Read more: How Ranunculus Handled Seattle's Winter

No. Soak the corms in room-temperature water for three to four hours, then plant them straight into the ground, as long as no freeze is forecast. Presprouting indoors is optional. If you do it indoors, use fresh, consistently wet soil and a clean tray every time, because dry or reused soil is what rotted my corms.

Read more: How Not to Kill Your Ranunculus

Not to survive a Seattle winter. Row cover is a nice extra in zones 8b and 9a: it breaks the wind (which gives me longer stems), keeps the soil a few degrees warmer, and discourages cats and birds from digging in the bed. I add it when several days of below-freezing temperatures are forecast.

Read more: Nancy Drew and the Mystery of the Turd in the Ranunculus

In my West Seattle garden, ranunculus presprouted in early October opened their first flowers in mid-April. November plantings were budding by late April, and the December and January plantings bloomed later, with flowers continuing into late June. That was an unusually mild winter and spring, so timing may differ.

Read more: When Do Ranunculus Bloom in Seattle? A Succession Planting Update

Ranunculus can handle short dips down to about 25 degrees. Corms exposed to prolonged freezing can freeze and rot, though, so if the forecast shows several days in the low 20s or colder, cover the bed with row cover or mulch it with shredded leaves. Seattle winters rarely get that cold for long.

Read more: Planting Ranunculus in Seattle Winter: January Update

Ranunculus can be considered technically tender perennials, but their return isn't always guaranteed. The corms go dormant around June. If left in the ground, they will likely start sprouting new foliage in late September. If you want to store them, wait for the foliage to die back, then dig them up, dry them, and store them somewhere cool and dark until planting time.

Read more: How to Grow Ranunculus in Seattle

My corms rotted during presprouting for two reasons: the soil dried out, and I reused potting soil between batches. Corms need consistent moisture while they sprout, and old reused potting soil builds up pathogens. Use fresh soil and a clean tray every time, or skip presprouting and plant outside.

Read more: How Not to Kill Your Ranunculus

I sell specialty ranunculus corms each year from late September until early March, with pickup in West Seattle or shipping to the continental US. The collection is just below. When it says "sold out for the season," join the email list, and you'll hear first when the corms are back.

Read more: Shop ranunculus corms

Everything here comes from my experience growing in West Seattle. The Puget Sound lowlands and the Portland area, however, share the same pattern of wet, mild winters with the occasional frost, so the September through early March window is a good starting point in Tacoma, Olympia, Everett, the Eastside and Portland. 

Check your own zone on USDA's hardiness map (planthardiness.ars.usda.gov), and keep row cover handy in case of an unusual stretch of sustained freezing.

Ranunculus, also called Persian buttercup, grow from corms rather than true bulbs. A corm is a dried, claw-shaped storage root (they look like calamari.) Soak them for three to four hours, then plant them tentacles down. (If they were a true bulb, like a tulip, you wouldn't soak them.)