Best way to store flower seeds for next spring?

To keep seeds dry, wrap two heaping tablespoons of powdered milk in four layers of facial tissue, then put the milk packet inside the storage container with the seed packets. You can also add a packet of silica gel in with the seeds. Replace every six months. Store each year's seeds together label and date them.

Store them in a cool dry location

dry and cool. If you leave air holes there is the chance bugs will invade. Some seeds require refrigeration.

I dry my seeds on a paper towel folded in quarter. Identify the seeds by writing on the towel then leave it on the unused end of the kitchen counter for a couple of weeks. When I think it's dry enough I slip the towel into a plastic zip sandwich bag. This is for tomatoes, pepper, and squash that come out wet. If you have dry flower seeds, just put them in a bag or those useless tiny rubbermaid containers that come in a set along with the containers you really wanted. No air holes, just throw them in a drawer until Spring.

I dry mine really well and then put them in snack size baggies and label them with permanent marker. This keeps them dry and in one place ( I have a three ring notebook I keep articles on some of the plants I have). I keep any collected seeds in baggies in those clear pages you can buy and I know exactly what I have at any moment.