I put them out in a ~4"x6"-8" grid and they come out fine. If you only have partial sun I'd space them a bit more, perhaps 4"x12". You also have to feed them more if they're tight together because the soil holds less food per plant.

If you grow different varieties, you may want to give them a bit more space between types, you can see I have a single row of asian tempest in the photo that was slower than it's neighbors and ended up kind of shaded.

Here is a link that might be useful:

I space the cloves 6" apart in the rows, with 12" between rows, and the rows go across my ~42" beds. The row spacing is a little tight for side dressing and cultivating when the plants are getting decent-sized, but I only grow a few dozen of them, so the intensive work isn't really a problem.

i have planted cloves 6 inches apart in 4 rows 8 inches apart with 2 ft spacing between the next 4 rows so weeding can be done, with good results. i have read that 5 inches between bulbs can be done. i would think more intensive care in growing would be required. 6 inches between cloves in a row is sufficient space for most any kind of garlic.

keith