A general rule of thumb is to collect seeds one month after the plant has flowered. Mark those plants with a ribbon or stretch tie from which you want to collect seeds. Some plants hold seeds for longer periods and seeds must mature before you collect them. Make sure seed pods are dry.
Keep records of what, when and where you collect seeds. Store thoroughly dried seeds in paper envelopes, in a sealed glass jar. Store them in a cool/cold, dark place such as a refrigerator or freezer. Make sure to label your seeds with the name of the variety and the date.
If you can not collect seeds at the opportune time, tie a piece of cheese cloth over the ripening seeds. Make sure they still get light and have air circulation. The ripening seeds will fall into the cheese cloth.
Be sure to ask for permission when collecting from private property and never take all the seeds from a colony of wildflowers! Remove seeds from flourishing colonies only.
Great books on seed collecting and wildflowers are available at Wedel’s. If you have any questions, stop by Wedel’s. We’d be happy to help.