Particle board and plywood are composed of pieces of wood products that have been pressed and glued together. Although they are popular siding materials for storage units, they are not most people's first choice in regions where it rains a lot. For if water does work its way into these products (a possibility enhanced by their composite nature), then you're lost.
Garden Supply Storage - Garden supplies tend to end up everywhere, especially if you do any potting in your shed. Always make sure to have a clean surface to work on. Old crates work well to hang from your potting area, where you can put small bags of soil, pots and watering cans. For seeds and other loose items, hang a ribbon and attach clothes pin. As you get small packets of seeds, use the clothespins to hang from the ribbon, taking down as needed. This keeps them organized and out of your workspace, so you can make the most of your gardening.