I don't think you could use too much compost or manure with alliums. Other than the fact both will break down and soil level lower over the seasons the garlic should grow quite well in what you have.

Use as much as your soil can "absorb", and add a teaspoon of bone meal into each planting hole :-)
Good luck!
Maryanne in WMass

Maryanne:
Should I use bone meal regardless of my soil additives? Last season I planted into the bed with just compost, no additional "boosters" and I mulched with ground up leaves.I ws very pleased with the outcome. Can I use the same bed again or should I rotate as with other crops? I am going to try adding the bone meal this time. THANKS HEIDI