Two to three inches of it sounds good to me. What material did you use to mulch?

Are you in a drought area of Ga? Is your soil exceptionally dry? clay? sand?

Karen

I am in the Atlanta area and I have the red clay. I used cypress mulch...maybe I should have used pine bark mulch or pine straw since I think they are acidic. I think we are under considered to be in a drought area.

While pine bark and pine straw both may test as being acidic they will not significantly do anything to your soil pH, so whether to use them or not is more a personal objective than altering soil pH. .33 inch of rain may not be enough to wet the mulch you have enough to allow moisture through, depending on what condition the soil under that mulch is in. As a rule I have found that woody mulches need about an inch of rain, especially if there has been none for a week or more, before the water from the rain will get through that mulch.

Yes, it would seem that the rain simply didn't get through the mulch.

The reason I asked what you had used is that sometimes if you mulch with that many leaves, they can clump up and repel water. Wood mulch generally doesn't do that unless it is old and undisturbed and is allowed to form a "crust" on the top. My neighbor's shredded wood mulch always does that by late summer- they don't plant much, pull weeds, or disturb the mulch in any way. It gets like a crust on top and water will run right off.

Karen

Did you water well before you mulched? You're supposed to start with wet soil. (I would have an irrigation system layed down too--either drip or soaker) Then you mulch the area and water the mulch. That way the it's set to hold the water in.

After that when you water it's under the mulch and it doesn't matter if the mulch get wet to the top.

Now even if the mulch settles a big rain will get through. Trust me 4 inches of good mulch will keep soil with lots of organic material wet for quite some time.

Mulch serves three primary purposes, to smother weeds, retain moisture and to feed the soil.

You only need mulch deep enough to accomplish the first two. If moisture is getting through the mulch, the microbes will turn it into food.

Your first post didn't specify the type of mulch you used and it is impossible for anyone to say how deep you should apply an unspecified material. 3 to 4 inches of grass clippings or straw may be what your garden needs but wood chips that deep may be excessive and detrimental, especially if the fungus that causes wood chips to mat into an impenetratable layer is present.

My experience with wood mulches is that I need to keep it fairly thin or I experience the same results as you. Usually about an inch and a half or so is enough for me. I use pine, not cypress here in the north. (Acidity of much should not be an issue.) If weeds poke through, I throw more mulch on them.

On the other hand, a short rain may not dump enough water to percolate down. What happens if you put a hose on it for some time?

Wayne