Isn't it spring yet?
The Extension calls S West MO the same as North MO and recommends planting onions at the end of March. I bought some more Candy onions at Joplin Greenhouse and will be planting them this week. I planted my other ones just after Valentine's Day before some verycold weather. They have been under a row cover and I haven't even looked at them since the snow.
Here is a link that might be useful: calendar