Ranunculus are one of my favorite flowers. They have gorgeous fluffy petals, come in an abundance of bright colors, and are so easy to grow! The best part of growing ranunculus for me is having fresh bouquets of these lovely flowers from the garden all spring.
Ranunculus Planting Guide:
Ranunculus are usually grown from corms, which are like little octopus-looking tubers that multiply into more little octopus-corms during the growing season. While ranunculus do produce seeds, the seeds may not grow into the same ranunculus as the mother plant, depending on pollination. Ranunculus corms are fairly inexpensive and also multiply a lot during the season so seeds are rarely needed. The larger the corm, the more flowers you are likely to get that season.
These plants grow best in temperatures between 35 and 75 degrees F, although they can endure temperatures down to 10 F. They go dormant in temperatures above 80 F, although they may last a little longer if they are grown in partial shade. I have found that when temperatures are high, even if they have not gone dormant yet, they tend to grow “leggy,” meaning the flowers get tall and topple over.
When to Plant:
Ranunculus love cool weather (but not blisteringly cold). I live in a region with mild winters, so I like to start pre-sprouting my corms indoors as early as possible in late summer or early fall, as soon as daytime temperatures start to drop below 80 degrees.
You can soak the corms in cold water before planting to make sure they get enough moisture to begin the growing process, but if you do, DO NOT SOAK FOR TOO LONG. An hour or two should be sufficient. Four hours is pushing it. They will continue to draw moisture from the soil once you plant or pre-sprout them. I once soaked some of my corms for 5 hours and they rotted (the octopus legs fell off or got really wiggly when I touched them). The corms are supposed to be firm, and the legs should not wiggle.
I prefer to pre-sprout my corms to make sure all the ones that I plant are going to grow (some corms never sprout, some may rot, and old corms especially do not sprout well). To pre-sprout corms, I use growing trays like these and put a light layer of moist soil on the bottom. Then I put the corms in, leaving a tiny bit of space between each corm, with the octopus legs pointing down. Finally, I cover them up with more moist soil (I like to add some pearlite to aerate the soil and prevent rotting), until all the corms are covered.
Make sure the soil is not too moist or the corms will rot. I like using moist soil that is on the “dry side” because I can always spray the soil with a spray bottle filled with water if the soil gets too dry. I leave the trays in a cool place (temperatures in the 70’s or below – the cooler the better) where pests can’t get to them and check on them every few days to make sure the soil is still slightly moist. The corms usually sprout within one to two weeks. You will know they have sprouted when they grow little white roots on the bottom and little white bumps on the top.
Depth and Spacing:
Once your corms have sprouted, it’s time to plant them outside (you can also plant the corms without soaking or pre-sprouting, just make sure the temperatures are right and the soil is well-watered). Plant them 2-3 inches deep, 4-6 inches apart, with the octopus tentacles pointing down. Cover with soil and water well.
Keep the soil moist but not wet. If the soil stays wet for too long, the corms will rot. Do not let the soil dry out completely or the plants will die. I like to use a moisture meter like this to check the moisture of the soil once in a while. You probably will not need to water until the plants start to sprout through the soil. I usually don’t water the soil much, if at all, until late winter or early spring, since the rain usually takes care of that for me.
Before planting the corms, I mix bulb food like this into the soil. Once the plants start to flower, I sprinkle more bulb food onto the soil at the base of the plants. I feed them with bulb food one or two more times during the flowering stage (around 2 months), and feed them one more time right when the plants have stopped growing flowers but the leaves are still green. For the amount of fertilizer to use, follow the instructions on the packaging.
Ranunculus flowers are ready to be cut when the petals are just barely starting to open. I’ve read that you should cut the flowers even before this stage, when the buds are colored but haven’t opened at all and feel squishy like a marshmallow. However, when I cut them that early, I’ve found that they don’t ever really open up as nice and fluffy as they ones that are cut when they just start to open. I also don’t like waiting too long to cut them and bring them inside because then little bugs start to make their home in the fully opened petals, and the fully opened flowers don’t last as long in bouquets.
Use garden shears like these to cut the flower stems as close to the base of the plant as possible. If you cut the flowers too high, more flowers may grow from the same stems, which you would think would be a great idea, except that the flowers will get too tall and fall over from their own weight. The more flowers you cut, the more flowers the plant will produce, so don’t be afraid to cut them!
Care of Cut Flowers:
Place the flowers in water as soon as you cut them. When putting them into vases and jars, add some flower food to the water. I use diluted sprite or a spoonful of sugar as flower food. Change the water every day or two to prevent bacterial growth if you want the flowers to last a while.
Grow More Corms:
If you want to enjoy ranunculus again next year, don’t uproot the plants as soon as they stop producing flowers. Continue to keep the soil moist until the green leaves turn yellow. Once the leaves have yellowed and your plants look pretty dead and shriveled, the corms are ready to be harvested. For how to do this, see my next post on harvesting ranunculus corms (coming soon).