There are numerous guides out there on how to grow great garlic, so I'm not going to re-invent the wheel on the subject. My family and I borrowed bits and pieces of many different opinions on how to grow great garlic. Here's a quick lesson on how WE did it at Drumming Grouse Farm....
1. Start with organically grown seed -- I recommend Certified Naturally Grown or Certified Organic. We see it as a way to make relatively sure that the garlic is grown without harmful chemicals and in a responsible way.
2. Plan ahead -- Define how much garlic you want to plant. Don't overwhelm yourself; I'd recommend not planting more than 1/4 acre to start (that is still a LOT of garlic!). Draw up the plan for the garlic plot paying particular attention to broad topics such as location, erosion, water access, sun exposure and so on. Get a soil test done and amend your soil using organic compliant amendments (do this when preparing the soil).
3. Start doing -- We started with virgin pasture filled with lush grasses. After mowing, we staked out the corners of a 100' long by 80' rectangle. Next, we tilled that plot with a 18'" walk-behind tiller (not ideal). It took about 3-4 passes total to break up the grass. Then, we put a wooden stake at each corner of the beds. We planned on (25) 30" wide beds with 18" aisles in between. Once staked, we strung twine to the perimeter of each bed. Then, we got out the shovel and started scooping soil from the aisle and throwing it on the beds to raise them up (lots of work). Finally, we raked each bed to break up any large clods and to achieve some uniform soil levels. Probably not the most efficient method of starting our garlic plot, but it got the job done!
4. Occultation -- Tilling up the soil also moves new weed seeds to the surface. Not wanting to deal with that headache later on, we chose to conduct occultation. By watering and covering with an occlusive tarp, weed seeds are provided a perfect growing environment. Under the tarp, the soil is moist, dark, and warm. Weed seeds germinate and strain to find light. Eventually, while searching for light, they run out of their stored energy and die leaving a sterile seed bed for your garlic. We watered our newly created beds heavily in September and covered with a 6 mil silage tarp for about a month. After that month, we found thousands of weeds had sprouted and died.
5. Plant -- As a general rule, plant a few weeks before your first hard frost. For us, this was early to mid-October. We chose to plant our garlic (remember--tip up!) using a 5" in row and 9" between row spacing. This provided our garlic with plenty of space to achieve seed quality size, but also allowed 500 bulbs to be planted in each bed. We built a peg board using those spacing dimensions to aid in creating a hole for each clove to be planted in. Since we live in a colder northern climate, we planted each clove so that the top of each clove was about an inch below the surface. For areas where frost heave is a major concern, I would recommend planting the tops of the cloves at 2 inches below the soil (in addition to mulching).
6. Lay drip lines -- Overhead watering with a sprinkler is fine, but drip lines are easier to work with, use less water, and get water to precisely where it is needed. After a good preliminary watering right after planting, you won't need to turn the water on for the garlic until late spring (depending on climate of course). I recommend laying the lines in the beds right after planting. We didn't do it that way. We waited until spring to put in the lines...which meant we had to remove all of our straw mulch, lay the lines, then replace the mulch. Lots of unneeded work.
7. Mulch -- Using mulch keeps moisture in, helps regulate soil temperatures, prevents frost heave (your bulbs will get ripped out of the ground when this happens!), and smothers weeds. We chose to use straw mulch. We used approximately (4) 20lb bales per 75' garlic bed. This provided a mulch layer of about 2-3 inches. We live in a zone 6A climate and this seemed to work just fine; 99% of our garlic bulbs came up thru the mulch in the spring with no issue.