Jiffy Propagation Pellets — Peat Compressed PlugJiffy Propagation Pellets The Classic Peat Compressed Plug Jiffy pellets are the classic propagation medium compressed peat plugs wrapped in a fine mesh net that expand to 7 their size when soaked in water. Ready made seed and cutting substrate with optimal pH and air to water ratio built in. Add water, pop in your seed or cutting, and you're done. Industry standard for decades for a good reason. Why growers choose Jiffy pellets: Expands 7 when soaked