We planted Allium sativum, common garlic, last fall in zone 2. The plants are doing great, I am going to harvest them when the bottom third of the leaves are yellow. For winter protection, I mulched heavily with wheat straw, rather than using loose straw I put down large chunks of old straw from the huge square bales. I am not sure how they will do in a raised bed over winter, I guess you can mulch heavily and see how it goes.

You know I keep hearing about people planting garlic in the fall but have never tried it. I'm not sure as to how long your growing season is, but here I plant mine as early as the soil is workable, about the first 2 weeks of May. I leave them in as long as possible, usually until the end of October, or if snow threatens a bit earlier. One thing I've heard of, that I've done for years, is to never buy new seed. Apparently garlic will acclimatize to your area and to your soil, so you always have to use your own seed. Another thing is to not plant garlic close to onions as they compete and neither will amount to much ( learned this the hard way, three years running, sheesh!). This is how my mother and her mother have always grown garlic and ours compares to what is in the grocery store, if not bigger. If your growing season is not as long as mine, then maybe fall planting is what you have to do then.
Good luck,
Laurie

I don't think your raised beds will be a problem. I was looking someplace on the 'net for info on how deep our soil freezes here, and couldn't find it. Perhaps you could call the University Extension Service. But I'm sure it freezes more than a foot deep, so no matter where you plant your garlic, it will be in frozen ground. Also, I have perennials in a 3-foot raised bed, and they thrive. I think the only plants that would be detrimentally affected by being in a raised bed are ones whose main growth parts (in this case, the garlic bulb) would be below the frost line. Since the garlic won't be below that line, no matter where you plant it, it shouldn't be affected one way or the other. It might freeze sooner (depending how wide your raised bed is and where in the bed it is planted), but then it would also thaw sooner. Depending on our snow cover this year, 8 inches higher would be enough to lose snow cover too early (of course, that could happen in the ground, too!), so make sure it doesn't start to thaw early enough to kill it.
You might go to the Saturday Market or one of the Farmers' Markets around town and ask some of the farmers if they grow any garlic, or check at the State Fair.

I think the issue is freeze/thaw cycles damaging the garlic. I wait until the ground is frozen before I mulch, the idea is not to insulate but to prevent the freeze/thaw cycles that take out bulbs and perennials. A raised bed would likely be more prone to freeze/thaw and thus more damage.

Fall planted garlic comes up early in the spring, the new growth takes a lot of frost without suffering any damage.

Thanks for all your ideas. We'll insulate well after the ground freezes.

Here is the reply I got on the garlic forum:

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Posted by: UncleJohn z4 NH (My Page) on Sun, Aug 14, 05 at 14:35

Hi Mike,
This fall I am planning on using one of my raised beds (8" x 4' x 32') for garlic. While New Hampshire is not as cold as you undoubtedly encounter (we have weeks of single digits, but it is rare for similar extended periods sub-zero) I am confident it will work for me. I am considering mulching the sides of the raised beds as well as the tops, and you should certainly do so in Alaska. If you were to add an additional 14" - 18" of mulch a foot or two out against the sides of the raised beds you should be set. Of course you should still have 6" - 10" of mulch above the bed.

I guess it comes down to how deep your frost line gets (snow is an excellent insulator); you should be able to protect your raised bed with mulch so that it fares no worse that an in ground garlic plot. In general, I would encourage you to try it; I think you odds are good, and the rewards are great.

Update- z2-3 Anchorage

Both the in-ground and the raised 18" tall wood-frame beds did just fine for overwintering, we had lots of garlic! Most or all plants of all varieties survived under 6-10" straw and leaf mulch. Took a long time to thaw in spring, the beds appeared frozen through, and plants seemed none the worse.

Siberian was by far best performer with consistently largest bulbs, and they are keeping much better than other varieties too. Small downside is that cloves are "sticky" when cutting open compared to other varieties.

Music, my second favorite of the bunch, was very pretty and very tasty but all bulbs were small. Spanish roja stood out for flavor, but size was variable by plant, shriveled quickly in storage. Other varieties - including chesenok red, korean red, bogatyr, killarney red were unremarkable, small and stored poorly.

Thanks for all the advice. It's been much, much colder this winter so we'll see how the garlic fares this time out.

Hello, I planted and root fertilized 50 stiff necked garlic cloves last October without any mulch in 8 inch raised beds. Today-May 22, 2010 I have 50 6 inch garlic plants. I guess I didn't have to do anything special for last years planting. This year may be a different year tho. Good Luck, Douglas

I'm a little further north than you :) In Fairbanks..I just wanted to say, great follow-up!! I wanted to know what you found out, and am grateful you shared what you learned!!!