First get them out of the plastic bags before they get fungus. They usually do get fungus you can use 10% bleach or peroxide water and dip each one before you plant them. Since you are in zone 10, I would plant in pots according to size. The big hostas start off in a three gallon pot, plant with the crown at or just above the soil to prevent rot. The smaller ones you can do one or two gallon pots. By planting in pots you allow more cold air to the roots in winter because they need a cold spell, they are dormant. Sometimes you can do everything right and some will not come back in spring because they need a good cold spell, some more than others. I try to choose Hosta that have a low chill requirement. The following article helped me a lot and remember hostas like a lot of water, also in zone 10 you will need total shade. Hope this helps!
http://www.plantdelights.com/H...
