Hot water treatment is used to reduce or eliminate disease in garlic. It’s necessary to do this before planting your garlic to keep your soil clean. After separating your garlic into cloves, put them in netted bags and treat before planting. I use a soil/compost thermometer to measure the temperature and a candy thermometer works too (needs to show 120 degrees). A kitchen sink works fine for a small batch of garlic, and the hot water from the faucet may be adequate to get it to the right temperature at first. Use a lot of water to help maintain the temperature better. Have a pot of boiling water handy.
1. Pre-soak bath - Soak in water around 100°F for 30-45 minutes. This pre-warms the cloves so that the temperature of the hot- water bath is easier to maintain.Temperature doesn't have to be precise at this point.
2. Hot-water bath – Take the cloves immediately from the pre-soak and put them in a 118-120°F hot-water bath. Maintain this bath at 118-120°F for 20 minutes. Start timing when the water reaches proper temperature.
The temperature of the hot-water bath will fall when the cloves are added. You
need to have boiling water handy to quickly raise the temperature. Stir while adding boiling water. DO NOT LET WATER GET HOTTER THAN 120 DEGREES!
3. Cool bath – Immediately submerse the cloves in a cool water bath for 10-20 minutes. Cool tap water is usually fine. (64-72°F is a good temperature).
here is a trick to keep the thermometer upright