James,
If you want a higher percentage of sprouting you might want to try a few tweaks to your plastic bag system:
1) Use heavy duty, Zip Lock, quart freezer bags, no more than 2 BBs to a bag.
2) Stand BB upright, buried 1/3 to 1/2 its length.
3) Use about 1 cup of your regular mix dampened but drained of water. Some people add water to the bag, then thoroughly drain.
4) SEAL the bag. No holes. In this manner, it acts as a mini greenhouse. (
reason for heavy duty freezer bags) If you notice the bags trying to "shrink wrap" the bulbs during the sprouting time, open and reseal.
5) Be sure to add a potting label in the bag or at least make a note of the name and date on the outside of the bag.
I stand mine up in three rows of 6/7 bags each in 16" x 16" nursery trays and place in a sky lit attic so there is plenty of light. Some trays end up in my office in a sunny window but not too hot to "steam" the BBs in their sealed bags. If your BBs are started before June, you should have many growths pushing to come out the top of the bags by October. At that time, I open the bag enough to let the growth come out, wait until I have a half dozen or so at this stage, and then pot them up into 3" pots, using the mix that was in the bag and adding more when necessary.
I get 90% or higher success rate doing it this way. The secrets are keeping them warm, keeping in bright light and getting them
started early. Even with a late start, you should have most of them ready to pot out by next spring.
Cym Ladye