The Mammillaria seeds and the Lithops seeds should both be sown on top of the soil and not covered, they need light to germinate. Some people do cover with a very thin layer of very fine gravel or coarse sand, not enough to block light. I don't.

Cover with plastic again, the humidity is very good for germination. Also, they probably need more heat than they are getting. Anything up to about 90F is certainly beneficial. Some people report good results at 105F for the Lithops, I haven't tried it. Cooler temperatures will give slower germination. Judging temperature is very difficult, I germinate almost everything in an enclosed propagator where I can take the temperature fairly accurately. I have found temperatures during the day between 75F and 80F seem to work well. Most seeds don't mind if it cools off at night, Lithops certainly don't, but they will germinate more quickly if you just keep them warm. Remember that after germination you should definitely let them cool off at night, down to 60F or below is good to keep them strong and compact.

Some seeds very fresh off the plant may germinate very slowly. The seeds are not always fully ripe when the fruit matures. This is especially true of Lithops if you broke open the capsule before it was prepared to open naturally. You'll just have to give them time. You might want to let the soil dry out for a few weeks, then wet it and start again. Probably nothing magic about doing that except that it will let the seeds get their act together and then all germinate together. If you just keep them warm and humid then they will probably germinate one by one over a period of many weeks.

shrubs_n_bulbs,
Thank you for your advice. I did spray the seeds today with a water sprayer, so maybe that will uncover some of the soil from the top of the seeds. I have a question, maybe this will work better than anything I can do right now. Can I let both sets of seeds completely dry out and leave them on an eastern windowsill (this eastern window sill receives little light if any during the brightest days here), neglecting them until it gets warm outside this summer and then try sprouting them? It should get up to 80 or 90 degrees outside during the summer here and I could try putting them in a southern, eastern, or western window (I have forgotten how much light our eastern and western windows receive during the day... I know the western in my room gets a bit of afternoon sun) where it is warm and gets abundant sun? I think since it is so cold here, the temperatures are fluctuating so often, and the lighting is limited, I might have a better chance sprouting them in the summer. OR would this only harm the seeds in one way or another or make them not sprout at all? Thank you for your help. I would have placed them somewhere until this summer and then planted them, but being as much of a beginner as I am, I was afraid that they might die or become sterile if I didn't plant them immediately... I am clueless!

Elizabeth

Elizabeth