Always add organic matter to prep a new garden and then organic matter again at least annually.

I would suggest a 1-3" covering of the garden with compost. You can just leave it on top, but your soil will be conditioned much faster if you work it into the top 3-6". Shovel, tiller, whatever.

After that cover the area with an organic mulch (dry grass, hay, straw, small shredded wood, shredded leaves etc) to keep weeds down and conserve water.

You can start planting immediately after adding the OM.

Happy gardening.

To clarify two of the above points: you can start planting as soon as the soil temperature is suitable for the specific plants/seeds you intend to grown (lettuce, peas, onions, potatos will tolerate rather cool soil, but beans want their soil very warm). Plan *where* you want what in the garden and then mulch all paths now -- but leave the beds/rows unmulched until the seedlings/transplants are several inches tall, and *then* add more mulch closer to each plant.

I'd suggest getting a copy of "Square Foot Gardening" by Mel Bartholomew for good info on growing vegs for the home (a used book is fine). Very sensible and also has good soil info; even I use his schedule for consecutive planting :) He doesn't use mulch because of intensive planting, but otherwise his info is superb for the home gardener.

If your brother has just tilled the area and mixed the grass in with the tillws aoil you will have a grassy weedy mess. Those bits of grass will grow!!
But on the other hand it won't be nessary to add organic matter to the soil this year....
You can plant pretty much any time now in Indiana....but I would hold off a week on tomato and pepper plants.
Linda C

-- But on the other hand it won't be nessary to add organic matter to the soil this year.... --

?????????

If one mulches properly - that means with a sufficient amount of mulch to block all light from the soil, there shouldn't be much, if any, grass growing up. If one wants to be positive that there won't be any grass sprouting, then put down approx 6 layers of sopping wet newspaper onto the soil and cover with 2" to 3" mulch -- and before anyone else comments - if you are fighting Johnson grass or similar evils, it takes about a 1/2" of wet paper to form a good barrier, but I sincerely hope that the new garden was not in a patch of johnson grass. The only difficulty with using paper is that one must be careful that *all* of the paper is *always* covered with mulch - exposed paper will wick any moisture away from the plants. You will likely find yourself adding a bit more mulch during the summer, especially on paths where feet and wheels have a tendency to push the mulch aside. The paper will gradually disintegrate and next spring you will find a thin layer of nicely decomposed soil to enrich your garden. The only weeding you should have to do is while the transplants and seedlings are quite small; I spend less than about a 1/2 hour a week keeping 4 long flower beds and 2 large gardens completely weed-free. Note that if you follow Bartholomew's intensive planting plan, your weed-pulling time will be about the same [about 2 minutes per 4x8 bed] -- we all have wind-blown weedseeds trying to sneak in close to a good plant's soil, but it doesn't take long to pluck up the weed sprouts.

If you want a truly productive garden, you will make it a practice to always 'return more than you take out' of the soil. This means adding organic matter, which is easiest done through regular mulching. If you are fortunate enough to start out with rich soil, don't waste nature's work! If your soil did not start out rich and friable, then the time spent in adding additional organic materials before planting will be more than paid back in healthy, productive crops.

So I want to be certain of this:

I need to work in 1-3" layer of organic material (compost) into the soil. I can then plant my vegetables, except for the tomatoes and peppers....I need to wait a week. After I have my plants in then I can put down a layer of straw or grass clippings to keep the grass/weeds from growing up. If I plant seeds then I have to wait to mulch till the plants are tall enough.

You got it!.

I would be careful of a garden that was grass and was tilled only once though.

That is how I started my garden and I found that about 10% of the grass was able to regrow (KBG). A second tilling took care of it. If you still have access to that tiller you might take a look at the soil in a week or so and if grass is growing either till again if it is all over or use a weed hoe to disturb it again. Alternately you can just skip it and plan to use newspaper and mulch to kill it.

If you tilled in the sod....you have a lot of organic stuff in the soil....you shouldn't mulch until after the seeds have their 2nd set of leaves, at least.....the grass will grow between the seedlings.
You should have removed the sod and set it aside, dug about 6 inches of soil out of the bed, put the soil aside, placed the sod back in the hole and replaced the soil. That's called double digging. Lots of work, but makes for a very good start for a garden. Not many seeds 6 inches below the soil surface....and the sod goes back for compost.
In my experience, even a second tilling won't keep those grass roots from re growing.....even 2 inches of mulch won't keep them down.
True, you can't add too much organic matter to the soil....well let's say it's hard to do...but with the sod mixed in you really don't need to add more.....and with the mulch you will put down tilled in that will do for next year...
But more compost is always good.
Linda C