Garlic spends about 9 months in the ground, more time than most other garden fruits and vegetables. A cool spring and early summer can delay harvest, while hot conditions can speed up a harvest.
The best time to harvest is often a matter of balance and will depend on your growing conditions, climate, and region. Below I will go over some signals to look for to best judge when your best time to harvest will be.
A typical garlic plant has about 10 leaves. Each leaf represents a wrapper around the garlic bulb.
As the time to harvest grows near, you will begin to see the bottom leaves start to die and begin to lay on the ground.
Each green leaf still standing will represent an intact protective layer (wrapper) on the mature garlic bulb.
As you watch the leaves begin to dry, you will know that harvest will be coming soon.
Bulb formation happens in the last 4-6 weeks, with the majority of bulb development happening within the last month. This is when they are gaining weight and size, so it is very important to NOT harvest to early.
Try to harvest when you see 4-5 leaves lying on the ground. This will give you 4-5 good protective layers around the garlic bulb. Another 1-2 layers will be removed once the garlic has cured and you begin to clean the garlic, which will leave 3-4 layers for protection around the bulb during storage.
Just as you don't want to harvest to early, you also do NOT want to wait to long to harvest. The longer the garlic is in the ground, the more wrappers will disintegrate. This could leave your cloves and bulbs with little to no protection.
Harvest is easiest if the soil has had some time to dry out. We usually stop watering about 10 days to 2 weeks before we begin harvest. (3-4 leaves dry on the ground)
Some areas of the country have large amounts of rain, and the soil will not be able to dry out prior to harvest. Excess moisture in the soil could cause staining on the bulb - this will not effect the garlic flavor, but you may have to cure your garlic longer to allow the bulb to properly cure.
On rare occasions, where the ground is very wet, there is a chance of root or bulb rot. If you happen to have saturated soil or muddy conditions at harvest, try to remove as much of the mud or dirt and hang the garlic where it can get plenty of airflow, adding a fan if possible. Keep the garlic out of direct sunlight, as it can sunburn and shorten the shelf life.
We leave the roots and leaves on our garlic bulbs while they are curing. The curing process is complete when all of the leaves are completely dry and the outer layer of wrapper easily peels off of the bulb.