When pollination is successful, after the flower fades, the ovary will begin to grow. Normally, the seedpods ripen in about nine weeks. As they ripen, the pods go from green to yellowish to brown. If pollination was not successful, the pods do not enlarge and ripen, they wither and turn brown early.
In the garden, when pods are ripe, they split open in three sections, throwing the seeds out. Pods typically do this on warm days when you are away from your garden! The seeds are not small, but being brown, they are very hard to see when lying on the ground.
After collecting, you may sow the seeds when fresh, or store them. To store, seeds should be air-dried in paper bags for a week or so in a warm dry place, and when thoroughly dry, held in a cool, dry place.
PCI seeds can live for several years when dried and stored properly. One member germinated seeds that were twelve years old.
SPCNI holds a seed exchange every winter. Members collect and save seed during the summer and fall in the Northern Hemisphere, and send word of their seed donations to the seed chairman by early September, with seeds usually following in October. Check the website or latest issue of the Almanac for the name and address of the current seed chair, and for current practices for donating seeds.
Ovaries or pods are usually mature enough in 8-9 weeks to hold fully mature seeds, even when pods are not yet brown. Several members have experimented with picking stems at this age (8-9 weeks) and cutting open pods to remove seeds. In most cases, the seeds inside are fully mature and viable.
To contain the seeds, some gardeners tie mesh bags over the pods. These are often sold as organza party bags, in a variety of colors and sizes. These bags are open mesh, so water drains and dries quickly, keeping the seeds contained and in good condition.
To dry late ripening seeds, cut the stalks with pods, and let the seeds ripen and dry in the pods before shelling.
Lawyer, Adele. 1996. Seed: Harvesting and planting, SPCNI Almanac, Fall 1996, pp 10-13.