Answer: Hemlock seed, according to Michael Dirr's Manual of Woody Plants, can exhibit variable seed dormancy. This means some will need lots of pregermination treatment and others will need less. However, cold stratification in moist sand is suggested for 60 to 120 days at 40 or 41degrees.
Indoors, you may find that your refrigerator is close enough in temperature; keep the seeds in a tightly closed plastic bag or similar container and check them periodically. Alternatively you may have a cool garage or basement that would work. Outdoors, many gardeners find that an adequate method is to sew the seeds and then place the pots in a protected spot over the winter and simply wait for germination in the spring. (It should be protected against rodents as well as severe weather.)
Good luck with your hemlocks!
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