I am going to take another detour from discussing the various types of gourmet garlic, this time to talk about harvesting, processing, and curing garlic. Harvesting garlic is nearly upon us, and every year I receive questions from growers regarding when is the best time to harvest their garlic. There is not always an easy answer, since the weather, usage and cultivar will all influence timing. For example, garlic matures at different rates in different climates. Hot climates prompt garlic to mature faster, resulting in an earlier harvest season compared with cooler climates in which the garlic matures more slowly.
We generally begin to harvest in mid-July. Approximately two weeks before our prospective start date, we begin to tinker with our soil moisture. The idea is to strike a balance between having enough moisture to keep the roots damp, allowing the bulb to continue sizing up, and having enough dryness above the root level to prevent the decaying outer skins of the garlic from attracting pathogens which may compromise the bulb. For those prior two weeks, we try to keep the soil moisture around 25-30%.
Allowing the soil to partially dry makes removal of the bulbs more straightforward. Bulbs are also easier to clean since drier dirt can often be simply shaken or brushed off. Finally, a dry soil will give you a head start on the curing process, making post-harvest storage less risky and variable. Be wary, however, of allowing your soil to dry out too much or too soon, since overly-dry soil forces garlic to early maturity, resulting in smaller bulbs and less overall yield. When unsure, always err on the side of moisture.
Ideally you will be able to control your ground moisture, but unfortunately, the weather does not always cooperate, especially in regions that are less arid. Rainfall, although helpful earlier in the season, can cause havoc near harvesting time. Wet soil makes the bulbs difficult to lift, and the threat of rot is ever-present, especially when combined with high heat. If possible, you should delay your harvest until the soil has partially dried. This is, of course, not always practical, especially if you have a large area to harvest. It is better to harvest in moist conditions than risk leaving the garlic in the ground where it is susceptible to rot and over-maturing.
If you do have to harvest in moist conditions, ensure you store the harvested bulbs in a dry place, with good air circulation so that the surface of the skins dry as soon as possible. Never expose the bulbs to direct sunlight for any significant period of time, since this can cause discoloration of the bulb skins.
So, you’ve got your moisture levels right. When can you harvest your bulbs? This is a tricky question, since harvesting too soon prevents the flavors of the garlic from reaching their full maturity, but too late and the bulb skins will dry out and split, exposing the cloves to pathogens, thus reducing their storage capability and making them unattractive for market sales.
Perhaps the easiest and most reliable method of determining when to harvest is the number or percentage of green leaves left on the plant. As garlic matures, the older outer leaves dry out and die, becoming yellow-brown and brittle. When the garlic is harvested these layers will be non-existent, having either come away from the bulb or being in the process of doing so. The remaining green leaves will provide the bulb skins. Generally, if you wish to sell your bulbs as gourmet, you want to harvest when the flavor of the garlic is mature, but there are still enough skins to provide a product that both looks good and will store adequately. If you are planning to store your garlic only for a short time for eating and/or seed, then you can leave the garlic in the ground longer, allowing the flavor to mature further. If you do choose the latter, make sure that you regularly dig away the soil around a test bulb, to confirm that the skins are not splitting as the garlic over-matures.
We tend to harvest the majority of our garlic when there are approximately five, or 50-60 percent of green leaves left. The garlic is mature at this point and this method allows for the loss of one to two skins to cleaning and curing, resulting in a marketable product that can also be stored for months.
There are, of course, always exceptions. Asiatic and Turban varieties, for example, should be harvested when only one to two of the true leaves have gone brown. They mature the earliest of all the garlic types, and have a tendency to split very early and easily, especially in dry climates. We usually harvest these types first, generally followed by the softneck cultivars. Finally, the rest of the hardnecks are harvested based on the leaf coloring of individual cultivars. This order may vary from year to year due to variability in climate and plant vitality.
How you harvest depends mainly on how much garlic you have. If you have a relatively small amount, it is easy to harvest by hand. Rather than simply pulling the garlic out, however, loosen the soil around the bulbs with a shovel, then gently pull on the stalk to free them. Since we have a large number of bulbs to harvest, we rely on a combination of customized mechanization and hand work to do it efficiently.
We harvest a single bed at a time. We begin with a wide blade that cuts off the garlic stalks approximately two inches from the bulbs. The stalks are then raked from the beds by hand. Bulbs are subsequently undercut and lifted with a modified potato digger, which cuts the roots at two to three inches, sweeps the bulbs up out of the soil, lightly jiggles them down a belt and then deposits them onto the top of the bed where they are gathered by hand. This both makes the bulbs easier to locate and retrieve, and also removes a portion of the dirt clinging to the roots. The harvested garlic is immediately placed in a cool, dry storage room equipped with forced air circulation, to begin curing while waiting to be trimmed for sale. Even with this level of mechanization, it still takes us at least two weeks to clear our fields.
Whatever the method you use to harvest, do so in small batches so that you do not have to leave the exposed bulbs baking in the sun. Next post I will discuss the curing and trimming process, which will help you get your bulbs both market and storage ready!