Soil Moisture & Watering Before Harvest
Drying soil conditions is a natural signal to garlic that it's growth and bulb filling period is coming to a close and that it needs to start preparing for the next phase in its life cycle as a storage bulb. This means that you should stop watering the garlic crop two to three weeks before harvesting the bulbs. In regions where you get more rain and the garlic continues to get moisture right up until harvest, maturity may just take a little longer and the garlic may need more drying post harvest while curing. Too much moisture at the time of harvest can increase the chances of root or bulb rot and can expose the cloves if the bulb wrappers have broken down. This is worse on heavy or saturated soils and not as much of a problem in sandy soils.
On our farm, the weather tends to be on the dry side once harvest comes along, although we do get the odd heavy down pour that can make things very wet. This means that we try to cut back on watering at least 3 weeks before harvest begins in case we do get some rain before the garlic has been dug up.
Harvesting garlic at the right time is a bit of an art and will depend on a few things. Garlic continues to grow as long as there are still green leaves on the plant. That means you want to leave the garlic growing for as long as possible to maximize the size of the bulbs, however you don't want to leave them in the ground too long and risk deterioration of the bulb and its wrappers.
For most hardneck garlic varieties, it is recommended that the plants are dug up when half the leaves are still green (upper portion) and half are brown (lower portion) or when there are still about 5 or 6 green leaves on the plant. The number of garlic leaves corresponds to the number of bulb wrapper layers, so as the leaves turn brown and die, the corresponding bulb wrappers begin to deteriorate. For example, if you have 6 green leaves when a plant is harvested you should have 6 layers of bulb wrappers protecting the cloves and allowing for cleaning and handling of the garlic. If you have no green leaves, chances are that your cloves will be exposed and unprotected.
For Asiatic and Turban varieties, harvesting on the early side is important. They tend to mature extremely quickly and can have their bulb wrappers split open even with only a few leaves having turned brown. These varieties need to be monitored closely and should be harvested at the first sign that the lower leaves are beginning to brown or signs that the bulb wrappers are beginning to deteriorate. This tendency to mature quickly is made worse by hot dry weather and moderated by cooler conditions.
Softneck garlic varieties can usually tolerate a longer period of time in the ground leading up to harvest. They tend to have tighter, more durable wrappers that can usually handle a little more stress. That being said, it is still a good idea to follow the same strategy described for hardneck garlic as they generally share the same principles.
On our farm, we tend to harvest our garlic on the earlier side, with at least half the leaves still green. Due to our heavier soils, we need the wrappers to be strong and healthy in order to handle the extra cleaning, as well as any excess moisture issues that might arise around harvest time.
Digging & Harvesting
How you harvest your garlic will likely depend on the amount of garlic you are growing. In gardens and small areas, a pitchfork or broadfork can be used to loosen the soil under the garlic before pulling. In market gardens or commercial fields, an undercutter bar is pulled behind a tractor and run under the garlic bulbs to loosen the roots and make harvesting easy. It is very important to be careful in order to not damage the bulbs while doing this task. Any nicks or bruises can be a route for pathogens like rot or mold and can also make the bulbs unmarketable or unable to store properly.
Once the garlic bulbs have been loosened from the soil, the plants can be pulled out of the ground and given an initial cleaning (i.e. brushing of excess soil) either in the field or in another area such as a shed. It is important to keep the bulbs out of direct sun light for any substantial period of time as it can damage them or cause green blotches that decreases their market ability. Once the garlic is harvested, the plants should be tied up in bundles of between six and ten and moved to a dry location such as a shed that has good air circulation.
On our farm, we generally run an undercutter bar under the garlic to loosen them first. If the weather is dry, we sometimes leave the garlic in the ground after undercutting for a day or so in order to kick start the drying process. Leaving them in the ground longer however can sometimes make cleaning them a little bit harder so it also depends on how nice looking we need the bulbs to look (e.g., Farmers' Market versus Seed). We prefer to do as much of the cleaning before the curing process as possible, however some farmers/gardeners choose to do all the cleaning after the curing is complete and the bulbs are ready for sale or storage.
Next → Curing and Storage