Harvesting: 

20-22 days (or more) after the final pollination, the lower leaves of the plants will wither, and pods will begin to turn yellow. Inside the pods, the seed coats will be turning brown. At this point, remove the nutrient solution or water from the reservoir and allow plants to dry until crispy brown (approximately 1 week). 

Harvest each plant carefully by cutting it off at soil level. Take care not to break off the pods. Harvest seeds from each plant separately by gently rolling the dry seed pods between your fingers over a tray. (Alternatively, you can drop seeds onto adhesive tape which is taped to a card with the adhesive side up.) 

Storing Seeds: 

Place the seeds in labeled envelopes. Include: the seed name, e.g. Fast Plants - rapid-cycling Brassica rapa - Basic, the number of plants that produced the seeds, date of harvest, total number of seeds produced, your name, and other pertinent information. 

It is important to test the viability of your seed crop by germinating 20-50 seeds on wet paper toweling in a plastic bag or petri dish. Place your germinating seeds under the fluorescent lights or in a bright window sill. After 24 hours, calculate the percentage of germination (or "viability") of your seed. Observe the vigor and uniformity of the germination. Note the germination test date and percent germination on the seed envelope. Typically, a germination rate of is 95% or better is considered to be a successful Fast Plants crop. 

For future Fast Plants investigations, store seed envelopes in a cool, dry place, (e.g. in a refrigerator in a moisture-proof, sealed container.) Ideally, the containers sould also contain a drying compound, (e.g., indicator silica gel, which can be obtained from a pharmacist or a camera store.) Seed that is stored in a dry and cool place will remain viable for over 10 years.