About 25% of the lawns we spray can be hydroseeded directly on native soil. The dirt must drain well and have been raked level. If you can hold your moist dirt in your hand, squeeze it, and still have it fall apart; you're in luck. You must be able to go down at least 4" with this type of dirt in order for it to be effective. Keep in mind, it's important for the soil to be loamy (with air) in order for the grass roots to easily penetrate it. This is the best type of soil to rototill if you are so inclined. Blading it with a Bobcat with teeth is also a quick way to loosen up the soil, if necessary. Always rake and roll your dirt if disturbed prior to hydroseeding, wet it down, and lightly scratch it with a rake. You can delineate the perimeter with a stick, rake, or upside down paint. Feel free to make a radius for ease of mowing.et.

At this point you are almost a candidate for bringing in light equipment. If the budget, size, or access to the project will not allow for this, then you can Roundup and weed whack the vegetation and amend the dirt by rototilling composted manure and sand into it.

Under no condition should you rototill uncomposted organic material into your soil. Doing such will create hot spots festering with bacterial fungi, creating red threat, mushrooms, and all sorts of unpleasantries for your lawn. Also never ever top dress an existing lawn or a highly vegetated area with topsoil. One will create an entire layer of deteriorating slime thwarting the health of a new lawn. When new grass roots encounter the viscous rift, it will surround the new root with a decomposing layer of moldy soil, ill suited for a healthy lawn. The only remedy when one has already prepared a lawn in this fashion is to regularly apply heavy doses of Dolomite or Capril (pelletized lime). Lime will help expidite the rapid decomposition of decaying organic material in your lawn and help stabilize the soil.

Another option in preparing your lawn (which I think is much easier) is to sod cut the vegetation with a "sod cutter" (if very thick and reasonably level) and import topsoil. A sandy loam with 20-40% sand, 20-30% composted organic material, and 40-50% fines (coarse sand, silt, and clay) is fine. As a rule of thumb, 2.2 yards per 1" per 1000 SF is a reliable formula to determine how much top soil you will need. Always rake and roll your dirt if disturbed prior to hydroseeding, wet it down, and lightly scratch it with a rake. You can delineate the perimeter with a stick, rake, or upside down paint. Feel free to make a radius for ease of mowing.

(Or Recently Excavated Soil)
You are ready to go. Having disturbed soil is a good thing. Air entrapment is crucial in establishing a new lawn. Grass roots have a much easier time embedding themselves in aerated (turned) soil than if left consolidated. You can determine the suitability of your dirt by doing a simple soil test: wet a sample of your dirt (from the top 3-4") squeeze it in your hands and hope it does not resemble potting clay. If the soil crumbles, you're ok. If it is ready for the kiln, import 3" of sandy loam.

Keep in mind the direction the water will flow when your top soil is final graded. A wet lawn is the number one cause of lawn failure. Try and slope your lawn so all the water will exit your lawn. If it looks like you have a dish or a low spot, either crown it with top soil or install a catch basin at the low point and discharge the water. A sandy loam with 20-40% sand, 20-30% composted organic material, and 40-50% fines (coarse sand, silt, and clay) is fine. As a rule of thumb, 2.2 yards per 1" per 1000 SF is a reliable formula to determine how much top soil you will need. Always rake and roll your dirt if disturbed prior to hydroseeding, wet it down, and lightly scratch it with a rake. You can delineate the perimeter with a stick, rake, or upside down paint. Feel free to make a radius for ease of mowing.

You are better off starting from scratch. Either bring in light equipment (Bobcat or Grader) or use a sod cutter. It is generally not worth the time and effort to Roundup and rototill this type of lawn unless you are under 1500 SF or so. For the time and expense to chemically kill this lawn, remove the vegetation, and rototill it, one could just as easily have sod cut and imported dirt, or called a Bobcat operator to do the same. In any event, the odds are that the topsoil is shot and it is necessary to import fresh topsoil. A sandy loam with 20-40% sand, 20-30% composted organic material, and 40-50% fines (coarse sand, silt, & clay) is fine. As a rule of thumb, 2.2 yards per 1" per 1000 SF is a reliable formula to determine how much top soil you will need. Always rake and roll your dirt if disturbed prior to hydroseeding, wet it down, and lightly scratch it with a rake. You can delineate the perimeter with a stick, rake, or upside down paint. Feel free to make a radius for ease of mowing.