When should I start these?
Ranuculus likes mild, cool weather – depending on where you are, you can create the ideal environment for your corms by starting them in the fall or wait until later in the winter/early spring.
Here in Central Ohio (Zone 6a), we start them in fall (wk 42) for transplant in an unheated house. If you’re in our same zone or colder and don’t have a greenhouse to transplant in, wait until late winter/early spring to start the corms to plant outside. If you’re in a warmer zone with mild winters, your corms can be planted with or without greenhouse protection. In all scenarios, you may still need frost cloth for protection on colder nights.
We sprout our ranunculus in a minimally heated greenhouse, but you could always try sprouting them in an unheated greenhouse, a basement, or another cool area in your house. If you aren't getting any growth, you could try moving them where it is warmer or put the flats on a heat mat. You just don't want them too warm or too wet after they have been soaked, so I would not keep the soil very wet while you are waiting for them to sprout.
How do I get a longer bloom time on my ranunculus?
We plant ranunculus in both minimally heated and unheated high tunnels. Doing this in conjunction with several planting successions means we have ranunculus blooming over the span of 3 months. Ranunculus yields 5 stems per plant on average.
I thought they wanted cold to sprout?
You should have success sprouting ranunculus in temperatures between 38°F &. 50°F. The warmer the temperature, the faster they will sprout and the more green growth you may get. Monitor them carefully during this process to ensure corms aren’t too wet or too warm, as both can contribute to rot. If you are starting them in January to transplant out, you may need help from some additional heat whether it's heat mat or bringing them inside your house to sprout them, depending on your zone. You want mainly root growth and not a ton of green growth before they get transplanted into an unheated house, so watch them carefully in the sprouting process.
What about anemone timing?
Anemones produce more stems per plant than ranunculus. Our plants generally produce continuously until heat renders them dormant, which means we can plant fewer successions of anemones than we do ranunculus, and still get a lot of stems. We prefer the varieties that produce larger flowers, which means sometimes they produce fewer stems per plant. We plant 3 successions of anemones starting in the late fall for our heated and unheated tunnels.
Any advice on plant health?
Most common pests and diseases are aphids and powdery mildew. Scouting for these problems weekly is a must to keep plants happy and healthy for maximum production. You want to catch any issues before they are a problem to prevent serious infestation. There are many products out there to help combat these issues, both organic and not, so we recommend doing your own research on what to use.