How much topsoil to spread over fill dirt?

Hi all,
We recently had some fill dirt delivered to level out some low spots on our property. There is one area about 10' X 10' that I would like to make a wildflower garden. How many inches of topsoil do I need to spread over the surface? Do I rake it in, or just leave it on top? Is there anything else I should add besides? Thanks :)

It is said that wild flowers don't particularly need a very fertile soil as in the wild there is no one but nature seeing to their needs really,
You don't say what you are spreading the soil on top of, if it's stony ground, you may want to remove any large stones away, if its just normal sub soil (unfertile soil about 2 spade deep under the natural top soil) then maybe spread the top soil you have about 4-6 inches deep, if it was always fertile soil, just about 2-3 inches would do,
Remember at this time of year, where you have bare soil you can bet your boots that come spring there will be loads of weed seeds sprouting, IF you don't get ground frost then you could spread and plant the wild flower seeds now as some of those seeds IN THE WILD need a cold spell to help germination when the warmer weather arrives to heat the soil,
There are lots of companies who provide wild flower seeds BUT, choose carefully as most are poor mixtures, if you go on line and google wild flower seeds mixes, you will be able to select what you need / like and how to care for the plants, most only need cut down after they flower and set their seeds again, but others need damp soil / full sun or other requirements. a wild flower area is very beautiful so it is worth doing it properly, I am sure others will come in and give you more advice also.
Good luck. WeeNel.

Greetings from Chicago. Same hardiness zone as yourself. Check with your Agriculture Extension Office and see what they recommend for your "Naturalized" area. There are many choices from native grasses to flowering plants. You don't say what else is planted around this 10 x10, sun or shade, etc.or if in middle of yard, trying to hide other features..... Establishing most native gardens require killing off any grass in that area. Alot of natives don't require alot of fertilizing either. You can till the area in the spring, wait for weed seeds that are present to germinate, kill off the weeds that do come up, and then seed or container plant your space. You can rake in topsoil above the existing grass, incrementally, so as to allow the rhizomes in the grass to spread and grow through the topsoil. It's like topdressing a golf green.

Most times establishing a "meadow", "naturalized" "wildflower" area is a 2-3 year project so plants planted in the first year have a chance to go to seed and help fill in the following year. Most people recommend burning a naturalized area after establishing.........Good Luck

PAgirl;

I have done something similar to what you are asking about. The great thing about native wildflowers is they are usually very hardy in less than ideal conditions. I went with about a 1 inch layer of bagged Scotts garden soil with no fertilizer. You could lightly mix it with the existing soil if you want to. We have a lot of pine trees here so covered the soil with pine mulch and pine straw. I would avoid using straw from hay or grass due to the amount of weed seeds it will contain.

There are several good seed companies who offer regional wildflower mixes or you could pick only the ones you want to plant. Some will be annuals and some will be perrienials. Also, pay attention to how tall the plant will get (cosmos will get to 6ft) and how aggresive the plants can be when you make your plans.

Wildflowers are species of flowers that have shown themselves to be hardy and self-reproducing, with little attention form the gardener.