Harvesting seeds
Most seeds are harvested in late summer. You should not harvest seeds too early, because they have to be fully ripe. You can usually tell by the ‘rattling’ you hear when you shake them, like in the pods of poppies and the seed hulls of foxglove. Or the tufts let go very easily. If you feel resistance, then they are not ripe yet and you should wait a while before harvesting.
Drying the seeds
After harvesting the seeds, spread the harvested seeds out on a large surface as soon as possible. This can be a newspaper, a shallow plate or a tray with a raised edge. Examine the seeds carefully and remove any insects and leaves. Put a label with the name of the harvested seeds on it. Spread the seeds in a shady, dry place, not in the sun. A room inside or in the garage, where at least some air can circulate, is the best place. The drying time depends on the seeds, the average drying time is between three and six days. Rather let them dry a week too long than a day too short. Drying too long does no harm, but if the seeds stay wet they will go mouldy and rot.
Cleaning the seeds
After drying the seeds have to be cleaned. Take the seeds out of the semi-transparent paper-like sleeves and carefully blow away any flakes, dust and dried earth, so as to prevent remaining mould from spoiling the fun.