I have never germinated seeds in a plastic bag although I have heard of many that do so successfully so what I am about to say is based on my thoughts, not on actual experience with the method.
I place seeds in a small cup and add only enough of a 9 parts water to 1 part of household hydrogen peroxide to cover them, but more likely enough water to allow the seeds to float. I leave them in very low light at room temperature and check back a couple of days later and daily after that to see if any seeds have germinated. I have read that the water/peroxide solution tends to oxygenate the water and thereby promote germination. Dr. Sue Bergeron who is a regular on this site has run controlled experiments with this method versus plain water and has confirmed that the water-peroxide method does promote seed germination.
I agree that hydrogen peroxide can be a dangerous chemical, but as the concentration decreases, while it still reacts with various materials, it does so much less violently. In the 1960's and before, concentrated H2O2 was used as the oxydizing agent in some rocket motors. However at 3% concentration (which is the concentration of household peroxide) it is quite stable when kept in a dark bottle. It will break down when exposed to light or elevated temperatures. When used in the 9:1 solution mentioned above, the concentration is far below 1%. My first thought when seeing the recommendation that a dilute solution be used to start daylily seeds, I thought it acted as an antibacterial agent, but it has been shown that is not the case.
My questions for you would be:
1. Did you use the dilution rate mentioned above?
2. How much did you put in the bag in relation to the amount of perlite? Was there free 'water' in the bag, or was the perlite only damp? I have heard of people using peat moss or potting mix rather than perlite as those materials absorb moisture and can be "wrung out" so there is no excessive water. However, the color of perlite makes identifying the seed much easier.
3. Where were the bags stored as they waited for germination?
4. What temperatures (approximately) did the bags encounter while they waited?
5. Were the bags exposed to any light - sun, overhead lighting, ambient room lighting, etc. - as they waited?
6. Were the seeds/perlite mixture exposed to air during the wait?
7. How long was it before you saw germination occur?
I do not stratify my seeds prior to germinating and because of that some seeds take much longer to germinate than others. If you extend the germinating time, you may need to guard against mold growing inside the bags depending on the amount of light, the availability of oxygen in the bag and the temperature.
