I live in Massachusetts and harvested some Snapdragon seeds to save for planting next spring. I've never done this, but have been told to let them dry, seal them in something airtight such as an envelope or small jar and store in a dark, cool place. One person suggested adding a desiccant to the seeds. What does that mean and is it an important part of the seed-saving process?
A desiccant will help, yes. A desiccant is a material that causes a drop in the moisture level of the immediate area. It is usually a solid. This protects the seeds from pathogens, which need water in order to grow, and also protects against premature partial germination, where the embryo over-develops before emerging, and dies before planting.
Silica gel would probably be a good choice to use, and is very cheap/common. It is usually found in packets like this: