If the ground is bone dry you should water, but if it has any moisture content at all you can wait for the rains.

Mulching after the ground freezes is a good idea in zone 4, but may not be necessary depending on what the other variety is. Red Russian will likely be fine without mulch, but it won't hurt.

I used to live in zone 5 and I think 4-5 inches is a bit too deep even there for garlic. Would suggest mulching with eight inches of straw and leave it there next spring. Garlic will come right through. Next year plant a bit shallower. Why did you plant so deep? Just curious.

I'm in zone 6 (can't change my info)and I've been planting my garlic 4-6 inches deep for years--Chesnok Red and Leningrad.

Dean,

How deep does the ground freeze where you are ? that is the answer to how deep to plant your cloves. Garlic can handle cold as long as it doesn't completely freeze solid in the ground. Over here in WA I plant so there is 1.5-2" of soil above the top of the clove. Then I use straw to insulate it. We see temps down to 0 sometimes and 10 above for a couple weeks during the coldest part of winter.

It all depends on your frost depth.

-bloo

How deep does the ground freeze where you are ? that is the answer to how deep to plant your cloves. Garlic can handle cold as long as it doesn't completely freeze solid in the ground.

In my zone 5 the ground can freeze to 3ft. My garlic (Siberian and Musik and pseudo garlic Elephant) are all in raised beds which become blocks of ice. All 3 typically have a 100% or close to 100% winter survival rate.

Definitely 4-5 inches is way too deep. Onions, garlics and shallots grow best when not planted too deep. I plant mine such that the top is covered with just "1" inch. The frost/freez will get down to more than 4 inches anyway so planting that deep does not serve any purpose. With the onions I would even move some of the soil away so the half of the onion bulb is exposed. Onions, garlics , shallots get nutrients from the soil through their roots and not the bulbs. The bulb can grow bigger when they are not burried too deeply in the groung.
cyrus

Definitely 4-5 inches is way too deep.

I respectfully disagree. While that depth is not required and a shallower depth may be beneficial, unless the soil is compacted badly they will emerge in the spring just fine and grow well.

In other words 4-5" deep may not be optimal, but it isn't so deep that all is lost.

I'm with Justaguy. I'm also zone 5 where the ground can freeze much deeper than the garlic. I've been growing Music (6 cloves per bulb), some soft neck that form little bulbs part way up the stem, and German porcelain (4 cloves per bulb) in raised beds since the ground becomes VERY wet in winter. I plant 4-6 inches deep, 6 inches apart. I used to lose some to rot but since I began a soak in 5% bleach solution, this is not a problem. I mulch lightly with leaves/grass mix from the last mowing. Been doing it this way for about 25 years with no problems and have been getting bulbs that are big and beautiful. (Bigger since I started using soy meal as fertilizer.)

Justaguy, I am sure that they will emerge, even if you planted them deeper than 4-5 ". But we are talking about optimum level. Bulbs, rizmus in general do not like to be burried too deep. If they need moisture/food their roots will go down and find it. I have just planted some garlics and shallots. Their tip ends were barely covered. The are 8 to 12 inches now. Actually I overlooked and left some of them just laying there naked and they were growing roots.
Last year I planted my onion sets too deep, maybe tops were about 2" under. Then I learned that it was not the best way. I experimented with some onions and removed the soil from around the bulbs. Those onios were much bigger than the rest.
Cyrus

Well, with planting at 4-5 inches, I get huge bulbs. About 4-5 to a pound.

We're talking about garlic here. I also plant onions and shallots closer to the surface. My garlic benefits from 6" planting.