It can take a long time for them to sprout unless the soil temperature is high enough. What I have done is to apply heat and they take off a lot faster. Depending on the temperature they can easily rot. Last year I potted them up and covered with saran wrap placed them under a rubbermaid with a 60 watt light bulb to provide the heat. If you try this please don't cause a fire. A heat mat might work and be a lot safer. I try for 80 degree soil temp. After they have sprouted (one to two weeks) I have placed them upstairs where we have a set back thermostat set at 72 in the mornings and evenings and 62 at nights and during the middle part of the day. In that environment they go almost dormant and grow very slow but it still gives a head start than planting directly outside having to wait for the soil temps to get high enough. Those that I have potted up and put directly in the 72 to 62 room temp have rotted. I originally used this set up to provide bottom heat to seed trays. I realized I could slip a container underneath. I used it last year for EE's and well as caladiums. Here is a picture:
