The backyard is 5-7k square feet, mostly sandy soil, and houses a dual septic tank system and drain field. One of the tanks of the septic system is only covered by about 1/4" to 1/2" of sand/weed mixture. The yard is horribly bumpy and uneven so it needs some major leveling. This spring I did some minor leveling and put down some generic Kentucky Bluegrass seed in some of the bare patches.

To the project: This fall my plan is to bring in top soil and use it to "topdress" and also level out the low spots (which may kill much of the underlying grass). I have a drag implement for my lawn mower which will make the job easier. I plan to give the yard a butch cut and then spread the soil. After it is level, I plan to over seed with Kentucky Bluegrass. (Thinking Scotts bluegrass mix) In effect, I am hoping to sort of "replace" the existing lawn by covering it and replanting Kentucky Bluegrass.

The problem: Right now the yard isn't horrible, but has large patches of every kind of weed known to man (okay, not every kind) If I work the yard well pulling weeds for a couple of days before I go into the project, will the kentucky bluegrass be aggressive enough to eventually force the leftover weeds out of the yard? I am not interested in using Round Up to kill the whole yard first before replanting, as I am trying to go for the more organic and family friendly approach. I also want to avoid tilling the whole yard, as there is lots of stuff to damage clearly buried right under the surface. One option I may use is to selectively apply Weed B Gone in the worst areas a few weeks before the project.

Not looking for perfection, just to add some good fertile soil to the yard, level out the bumps, and reduce the number of weeds. Thoughts/ideas? Recommendations on good blends of Kentucky Bluegrass? I am in Leslie, Michigan. Zone 5b.

KBG can spread quite a bit if the soil is balanced and healthy, and your grass is well fed. There are some cultivars that are aggressive spreaders that can take over a whole lawn if they are seeded in too high a percentage. It can't choke out weeds if the weeds are growing, but as a KBG lawn gets thicker and thicker, it makes it much harder for weeds and weed seeds to get a foothold. I would steer away from Scott's KBG blends. Scott's uses older mediocre cultivars for most of it's products, and the water smart coating means you are paying double for your seed. Determining which cultivars you should plant is a personal decision that depends on what you want out of your lawn. Many people want the darkest green they can get. Some want aggressive spreading, others would like early spring green up and good late season performance. What are the most important characteristics you want in your lawn?

Many people avoid using what will solve the problem just because they have this idea that "organic" is the only way to go. You can take a lot more time to kill what weeds you have---and end up being disappointed with the end result or --you can take the problem and solve it more in line with the amount of time you wish to put to it.

RoundUp, will kill the green in your lawn...and anything else that happens to be there. If you feell such additional greenery is felt to be too valuable to lose, then using the glyphosate is out of the question...but it is the only way to rid your lawn of what you don't want there.

However you decide to level it, it does sound like extensive tilling is going to be required--bumps cannot be just pushed down or leveled by raking.
A small tiller can do a somewhat decent job of removing hillocks, then raking to level and rolling where necessary.

As far as seeding, do look into the use of a combination grass seed...60 percent Kentucky Blue, 20 percent perennial ryegrass and 20 percent fescue--makes for a tough lawn that can stand up to most conditions encountered in north-eastern weather patterns. Do some research on the different types and what they can offer a lawn. I'm sure you will select the combo instead of one type.

The back yard is our main "play turf" so to speak. My 2 1/2 year old daughter uses the area daily. We also have plans to add a deck to the back of the house next year which will increase our use of the back yard.

Timeco, some important characteristics to be would be a turf that can stand up to foot traffic (not like Mall of America traffic, but a few kids playing in the yard kind), drought tolerant (sandy soil in full sun with no shade), should be able to spread at a decent rate. Do they make a dog urine resistant strand? lol. As far as color goes, I was thinking a nice green color would go well in the yard. :D

I do not plan on leveling out the bumps by simply dragging the yard, but mainly by bringing in top soil and filling the low spots and raising the whole grade. Won't tilling the yard eventually create uneven settling thus resulting in bumps? The other reason to bring in top soil is to add some good rich soil for the grass to grow in. Right now the bare spots in my yard are 90% sand and gravel and the grass just doesn't like it one bit. Those spots also happen to be some of the lowest. The top soil should kill 2 birds with one stone.

We have lots of sod farms in our area, I will see if I can work out a deal to buy some seed from one of them.