Bloodmeal is not commonly sold here and I do not grow organic, so I am planning to use calcium nitrate when watering my garlic after they start forming shoots. Calcium nitrate is also used in greenhouses and works well to prevent bottom end rot in tomatoes. It is commonly sold for farmers in huge bags, but last fall I found this stuff at reasonable prices in containers suitable for home gardeners, so I purchased enough to use for my tomatoes and all alliums.
http://www.yara.co.uk/crop-nutrition...ing-bulb-size/
Sari