Answer: This method does work, with a bit of perseverance and maybe some luck. First of all, be sure to pick the seed as soon as it is ripe and take it from the best, most robust plants. Pick it on a dry day and then be sure it is dry and insect-free before you store it in an air-tight container in the refrigerator.
Black-eyed Susan (Rudbeckia "Goldstrum" type) and coneflower (Echinacea purpurea) are both perennials and as such generally take two years to hit their stride for blooms so they take a bit of patience. Assuming your seed saving and storage techniques are good, these two perennials will often germinate within about two weeks under normal seed starting conditions. However, if nothing is happening after three or four weeks, try chilling them at 24 to 39 degrees for about three weeks and then try to germinate them again. Remember too that often perennial seed germination rates are not as high as those for annuals. (A somewhat easier way to propagate these is by division.)
Annuals such as marigolds may present another problem in that seed harvested from hybrids may or may not be viable and in addition it may or may not produce plants similar to the ones you saved the seed from. For instance, many F1 hybrids will not come true from seed and many of the triploid hybrids produce seed with very poor germination rates. So in this case the problems may not be specifically related to anything you do (or don't do).
Seed saving and starting is always interesting and can be addictive -- just be willing to experiment and keep good records so you can replicate the successes!
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