Coleus usually root well in damp vermiculite without rooting hormone but I do use it just to ensure success. You can take cuttings anytime. Pinch out any flowering tips. I like to plant at least two sets of leaf nodes (minus the leaves) below the soil line. Bright light is fine but no direct sun. You can invert a clear plastic cup or container over the cuttings for the first week or two to keep moisture close to the leaves until the roots start forming. Do let a little fresh air in under the "domes" every day. They should root in a couple of weeks. Water the vermiculite if it starts getting dry.
