Make a point of picking only plants growing in prime locations. Individual plants with many insect holes and obvious poor health are probably located at the extremes of their preferred growing conditions and may also have distinctly atypical biochemistries as a response to their compromised growing conditions. Always check around the vicinity after you have located a desired plant.; in fact, it should be stated that the best collector has scouted the area weeks ahead of going to collect seed – this needs to be a thoughtful and deliberative process. However, there may be times when there isn't any 'wiggle' room – in that case, still maintain a considered posture. Remember, a thoughtless collector can wreck havoc on an ecosystem. There may be a whole field of your desired plant over the next rise or around the bend in the road. On the other hand, this plant may be the only one in the whole valley – and should absolutely be left alone. Furthermore, a plant common in one state may be a rare, protected plant in the next state, or even the next county, so check with a local California Native Plant Chapter first if in doubt.
Certain conservation practices are always necessary. If a plant grows in large stands, never take more than a third of the plants' seed. If it is a large, solitary bush or tree, never pick more than a fourth of the seed. If the plant is an annual, do not exceed these suggestions – perennials will have the chance to set seed again next year, but even then, leave ample seed behind.
Wherever you gather, presume that you will come back the next year to the same place and find the plants still healthy. Don’t make a common mistake of looking many days for a plant, finding it at last, and taking a whole load of its seed back with you – it’s like you are punishing the plant (indeed the species!) for your frustration. And
most seed collected in gobs and
gobs, mark my words, will go to waste. Do not collect beyond your
ability to deal with the result.
Dry your seeds promptly upon return. Lay the seed on screens away from direct sunlight in a dry place and, above all, away from rodents and insects. Fear of insects and rodents have spurred me to use my food dryer to do the job as quickly as possible. Dry your seed as promptly as possible and, once dry, place in paper envelopes or in glass jars.
Store your seeds in a dark, dry and cool location, the darker, drier and cooler, the better. Make sure your seed stock is insect free before storing. It can be terribly disconcerting to find your stored seed has become insect larvae feed and you have nothing to show for your work.