Growing Ranunculus
Ranunculus can be planted in the Fall and overwintered or planted in the Spring. Depending on your zone, they may need to be covered to successfully make it through the winter. Here I opted to start them in the Spring. For Spring planting, deciding when to start your corms depends on when your Summer temps arrive (70°+) Ranunculus needs 90 days to grow and will flower for four to six weeks before going dormant. You’ll want to figure out when you start your corms depending on when you expect those hot temps. Here I wanted to start harvesting at the beginning of June and continue until it got to hot for the plants so I started them at the beginning of March.
The corms need to be soaked for 4 hours (this is the most commonly recommended amount of time and it worked well for me) in room temperature water. While soaking I prepared a 50 cell tray with each cell 2/3rd full of soil. You’ll want to use a potting mix so it doesn’t retain too much moisture. After soaking I placed one corm per cell and covered with soil.
I’ve seen different recommendations on if they should be placed under lights or not and opted to place the entire tray under our grow lights. During this time it’s important to keep the trays cool, around 50-60 degrees. I use a closet that doesn’t get any heat. Second most important is to not let the soil dry out but also don’t overwater it. I found using a spray bottle and misting the top of the soil every 1 to 2 days worked well.
You won’t see growth on top of the soil during this time but the roots are starting to grow. I would dig around every few days to check on them and make sure they were actually doing something. It took about 10 days to see green growth above the soil. At that point if you don’t have the plants already under lights you need to put them under lights or somewhere in your home that gets good light, but is still in a cool area.
I started hardening off the trays about three weeks after planting. Put the trays outside in the shade for an hour or two at a time and increase time and sunlight throughout the week. About a month after planting they were ready to move outside. They should be placed where they will receive full sun.
The area I planted in was amended with Dairy-Doo, an organic compost. Whether this was necessary or not I’m not sure, but I use it all of our flower beds so didn’t think it would hurt.
At this point is when you have to start watching the weather! They can tolerate temps up as low as 27 if it’s not for an extended period of time, but if the soil freezes the corms will rot and die. I covered the plants when our tempatures went below 30. You can use frost cloth or a sheet (if you use a sheet keep it raised off of the foliage) and remove it when temps rise above freezing again.
On the other extreme they also need protected from high temperatures. If you are expecting to get a heatwave or rise in temps over 70 (like we did this Spring) you need to keep the plants cool to prevent them from going dormant and not producing any buds or flowers. In the early AM water them with cool water and cover to give them shade. I use shade cloth but you could also use burlap or a sheet. Again, keep it off of the foliage.
I didn’t need to water with the amount of rain we got, but did check to make sure the soil was staying moist without drying out. It’s also recommended to fertilize every few weeks, I use a fish emulsion since I try to use the most natural options, but you could use Miracle-Gro or whatever fertilizer you like.
At 12 weeks I saw our first buds and they continued to pop up throughout the patch. The first few stems will be pretty short but as more flowers grow the stems will become longer. If you want to use them for cut-flowers, cut the stem at the base of the plant and when the flower looks like a marshmallow.
Once the heat of Summer hits here the plant will go dormant and the foliage will die back. If you want to use the corms again, leave the plant in place until the foliage is all died back. You can then dig up the corms and store them to use again.
