How to Know Exactly When to Harvest Each Garlic Bulb
How do you know when it is time to harvest the garlic? There is no pat answer as it varies depending on what part of the country you grow in and the variety of garlic involved. Different varieties harvest at different times as Asiatics and Turbans mature first, followed by Artichokes, Creoles, Rocamboles, Purple Stripes and Porcelains and, finally Silverskins. Since spring warms up from the South to the North, southern growers will harvest earlier than Northern growers. It also seems to depend on the weather; how soon it warms up to what extent. If high temperatures come early in spring and it stays warm to hot, harvest will be earlier than usual because it is the heat and sun that causes garlic to bolt. A long cool spring will delay harvest until after the usual time as the bulbs will mature slower and maturing is delayed. We usually start harvesting in mid-May or so whereas far northern growers may not begin until July or later.
Hardneck garlics will send up a stalk, or scape as it is properly called, a few weeks before harvest time. Some growers prefer to cut off the scape and some prefer to leave it on. There is widespread disagreement among growers about when or whether to cut the scape. Some say if you cut the scape it will make the bulb larger. Some say if you don't cut the scape the garlic will store longer and better-and make better seedstock. Some say you must cut off the scape at just the right time to get the right balance of size and storability or hardiness of the bulb. Some say if you cut off the scape too soon you will get big bulbs but that they are more susceptable to disease and short storability (just eat them first.) I suggest you experiment and see what works best for you in your situation. Most serious growers I know do cut the scapes while they are still tender and either eat them or sell them to gourmets - they're highly prized for their delicate flavor and they're only available for a short time in the spring.
Softneck garlics don't usually send up scapes but sometimes Silverskins do when stressed by adverse growing conditions. The Artichoke garlics form bulbils in the neck area just above the cloves. The Asiatic and Turban groups of garlics are classified as weakly bolting hardnecks usually send up scapes but not all. They're both very early ripeners and need to be checked for readiness to harvest as soon as the lower leaves start to die down, don't wait for the last six leaves or they will be overripe - they're unique in that regard. Dig down and look at the bulbs to verify if they are big enough. The Creole garlics also often send up scapes. All Creole scapes form an inverted "U" pattern - at least all that I have ever seen, as do Asiatic and Turban scapes.
The real secret to knowing when to harvest the garlic is to watch the leaves and they'll tell you when to harvest. Garlic leaves signal maturity by beginning to turn brown and dying. The lowest (and outermost) leaves die first and then the rest die from the ground up. When the lowest few leaves die down but when the first few leaves die, dig down to the bulb and look to see the size if the bulb and if it is big enough to suit you, harvest but if it is still too small, wait a few days longer for it to size up. Check again every few days until the bulb is big enough. During this time the top leaves are still growing.
Generally with softnecks, the time to harvest is when the lower leaves have all died down and only the top six leaves are still green. Don't wait for the leaves to all die down and fall over like onions do or you will be inviting trouble in the form of overripe bulbs that are unattractive and more subject to fungus, pests and poor storage. Also, the upper leaves of the plant are the ones that determine how many bulb wrappers the harvested bulb will have. If you let the leaves all die down then the bulb wrappers will all rot away and you will have bulbs with the cloves exposed and no bulb wrappers to protect them. Use these bulbs immediately while they're still good-the ones with good bulb wrappers will store longer and better.
On the other hand, research indicates that garlic left in the ground longer has more potency and a stronger taste. Since the cloves within the overripe bulb tend to splay out as they crowd each other out, it becomes easier to break the bulbs apart. In fact, I know growers who say they let the bulbs they want to use as planting stock stay in the ground a little longer than usual because shortened storage is not a problem since it doesn't have to store very long until planting time comes around. These same growers also leave the scapes on their planting stock while cutting them on the stock they intend to sell as cutting scapes makes those bulbs bigger than they otherwise would be.
All the plants of any given variety of garlic will come to maturity at about the same time, but some varieties will mature in the early spring and others not until mid-summer. As each variety approaches maturity, inspect the bulbs so that you can see when they get to the size and condition you want. You can dig down around a few plants to inspect the size and shape of the bulbs, being careful not to disturb the roots, every few days until you are satisfied they are ready to harvest. If they're not ready yet, carefully replace the soil and let them go a few days more then inspect again. If you are growing more than one variety, be sure to inspect some of each and harvest only the ones that are ready.
Once any given variety of garlic starts losing its leaves and there are still eight leaves left (a week to 10 days from harvest), discontinue watering and let the soil begin to dry out some so as to make harvesting easier - it's easier to pull garlic out of loose soil than mud.
When your garlic is ready to harvest, there are several ways to do it. It is important to remove the garlic from the ground without injuring it as it is still a living creature and germs can enter through wounds at a time when its ability to ward them off is diminishing. If you have real loose rich soil, you can simply pull them up by their necks as long as doing so will not tear or damage their necks or roots. Few of us are fortunate enough to have that kind of soil. For most of us the best way is to use a shovel or garden fork and slip the blade down beside them and then work it under them and pry them up from the bottom. Be very careful not to cut the bulbs as you do this. We use a thick, tractor mounted , wedge shaped blade to undercut them below root level and push them up without touching them. The blade gently breaks up the ground under and around them and we retrieve them by hand, lay them gently into a wagon with a sun cover and immediately take them out of the sun and into a cool shady place to cure out for a while.
Be very careful in handling the bulbs at this point and do not bang them together as that can cause them to be bruised and invite storage problems and ruin them for seedstock. Do not throw them onto the ground or into a wagon, place them down gently - you have spent a lot of time and effort to grow them right, don't blow it all now by handling them rough. Get them out of the sun as soon as possible as the sun can scald them or cause them to dry down too quickly and may result in problems.
Many large commercial growers plow them up, windrow them for a few day then cut off the tops and roots and store them, but it's not a good idea. They do it because of the economics involved with personal handling and the cost of building huge drying sheds. Growers who are more concerned with quality than quantity don't do that any more than they would use conveyor belts and let the garlic bounce into truckbeds from the height of three to five feet - which they also do. However you harvest, cure and store your garlic, always keep the different varieties separated and identified so that you will know which is which.