Cleome, also known as the "spider flower," is a showy annual that is fragrant, attracting butterflies and hummingbirds. Before sowing cleome seeds in the spring, they need to go through "stratification." Stratification is a method of immitating winter for a seed and then waking it from its dormancy in order for it to germinate. Cleome seeds take the change in temperatures as a signal to wake up. Stratification may sound difficult, but it is a simple process you do right in your kitchen.
Soak cleome seeds for 24 hours. To do this, leave them on the counter in a bowl of water.
Take your freezer container and layer the bottom with 1/2 inch of wet sand. You want the sand to be wet, but not slushy, and the container type that works best is a rectangular shape that is only two inches tall. Any shape, however, can work, and the size will depend upon how many cleome seeds you have.
Put your cleome seeds on top of the layer of sand, and then cover them with another 1/2-inch layer of sand.
Place the container in the freezer for four weeks and then move the container to the refrigerator until you are ready to sow.