No cut-flower garden is complete without ranunculi. I admire these flowers for hours each spring with their gentle, nodding stems and layers upon layers of soft, silky petals. Each plant gives you several cuts over a period of weeks, and your ranunculus bounty will make you feel like the richest gardener in the world. Ranunculi are a cool season flower, and it’s essential to get them started in Southern California in the fall. The ideal time to soak and pre-sprout ranunculus corms is mid-October for a late-October planting, with the first blooms appearing just after Valentine’s Day. You can succession plant these a few weeks earlier, and/or later, to extend your bloom time.
In the following, I’ll be discussing the different ways you can plant ranunculus corms. These are methods that I’ve tried and have had great success with! There is no better way to master growing this flower crop than to get out there, make mistakes, and get your hands dirty. You must be attentive to your corms at every step in the process so they don’t rot. Gardening should never require a lot of expensive materials and tools. If you don’t have something, look around and find something else to substitute. There is always a way to pinch pennies and use what you have to get near perfect results.
Soak your ranunculus corms in water in a cool location for 4 hours. I use an aquarium air pump to introduce oxygen while soaking, but that is not necessary. If you don’t happen to have one of these for making aerated compost teas, simply do the soaking in your kitchen sink and turn on the sink whenever you happen to pass by to introduce some oxygen to these living plants! After 4 hours, drain the corms, rinse with fresh water, and drain again.
Pre-sprouting isn’t a necessary step, but it allows you to keep the conditions perfect for your ranunculus corms while they germinate and may produce more consistent final results. I pre-sprout my soaked corms in peat moss (which you can find at your favorite local nursery or a store like Home Depot) before planting into the garden. To do this, add water to the peat moss in a bucket and work the peat moss with your hands until the water is incorporated and the chunks of peat moss are all broken up. You want the peat moss to be moist but not wet. Next, I line milk or bulb crates with brown paper, then add a layer of moist peat moss. If you don’t have any crates laying around, you can also use shallow plastic trays for bottom watering, or anything else you can rescue from the trash that will allow some airflow. The biggest threat to your corms is rot. Layer your corms on top of the moist peat moss, doing your best to prevent them from touching one another. Finally, layer more moist peat moss on top of the corms, and put a wet piece of paper on top to retain moisture. If you don’t have access to peat moss, I have used potting soil in the past with few problems.
Place your crates or trays in a floral cooler to sprout at 55 degrees. If you don’t have a cooler, you can place them in the coolest, darkest location you can find. I’ve pre-sprouted in the closet of our converted garage and also in a dark corner of an air-conditioned room with no issues. Check your corms every few days to make sure the grow medium is not too wet or bone dry, and respond appropriately.
Ranunculus corms sprout in 7-10 days, at which point they are ready to plant into the garden 1 inch deep, octopus legs down. This year I’ll be growing all of my plants 8 inches apart, but they can be spaced as close as 6 inches. Water the soil deeply after planting so the water penetrates several inches. Keep the soil moist until you see ruffled, green leaves emerge from the soil.
For a backyard gardener, the simplest way to start ranunculi is to follow the directions on soaking above, and then plant the plumped up corms directly into the garden (versus pre-sprouting). In Southern California, you should wait until the weather and your soil cools before you soak and plant. Late-October, or early-November to mid-November, is usually a good time. Plant your corms 6 to 8 inches apart, octopus legs down, 2 inches deep. Water the soil deeply after planting so the water penetrates several inches. You must keep the soil moist, but not wet, until you see green leaves appear.
Gardening is like honing any other craft. It requires you put the reps in, and with those reps come intuition and problem solving capabilities. I had a difficult time starting ranunculi my first couple of years growing them because I blindly followed the advice of other growers in climates very different than our own. Use your hard-earned garden sense, problem solve, and trust yourself. In our unique, Mediterranean climate, it’s very important you keep your soil moist, but not wet, after planting. It depends on the weather, but for me that means watering them every 3 days once they’re planted (unless it rains). Bend down and put your hand into the soil and make a decision from there. If we get a string of very hot October days with Santa Ana winds, like we usually do, hang some cloth for shade if you can. Sometimes this isn’t possible, so make it a point to water extra during the heat of the day with cold water to cool the soil and plants down. Remember ranunculi are a cool season flower and the priority is to keep the growing conditions as cool as possible.
Good luck out there and best wishes for an abundance of ranunculus flowers come spring!