Vernalization is a process that some plants, including garlic, undergo in order to produce a bulb. In the case of garlic, vernalization involves exposing the garlic cloves to cold temperatures for a period of time before planting. This helps stimulate the growth of the garlic bulb and ensures a good harvest. The temperature required for vernalization in garlic is typically between 32-50°F (0-10°C), and it usually takes around 10 weeks to complete the process.