Pre-baked/boiled leaves can often be purchased on dart frog forums and vendor sites. Some of them have a large variety of leaves so you can get several safe varieties that will look nice and also allow any clean up crews to thrive well on them. Plus they tend to use types of leaves that take longer to decay so they last much longer than many types of leaves. I would also keep in mind that natural leaves can host beneficial bacteria that can help the soil in the enclosure. Beneficial bacteria as well as drainage are needed or the cage can turn really smelly and septic smelling.