Spray new seed
I like to do experiments. (Never really left college.)
I sowed Scotts seed "High Traffic" June 20, about 20 seeds, in small containers. (Contains perennial rye in mixture). Temps about 80 to 85 during days. At five days it was about an inch tall at maximum. I sprayed a container with T-Zone on 6-25, 6-27, 6-30, and 7-5.
Unfortunately, there occurred probable insect injury on the new grass. Sharp pointed leaf blades were blunt and cut off as if by caterpillars or slugs.
Container sprayed with T-Zone on 6-25-2011 showed little or no injury. Other containers showed partial thinning of the grass sprouts. Untreated containers also became thin--probably due to insect injury by an unknown species.
A container treated with Drive showed no injury, except a few insect damaged sprouts. Drive killed young (2 inch tall) crabgrass effectively after 5 days, in a nearby lawn. No results yet on violets and clover.
Not shown. Container treated with Shaw's fert with Dimension 0.13 percent at about 4.75 and 9.5 pounds per thousand sqft. In this case, in the low rate treatment one sprout appeared, and in the high rate two sprouts appeared, plus one weed sprout.
The insect injury confused the results, as possible herbicide injury occurred also. But I suspect that it may be possible to spray new grass sooner than generally suggested on the product label. (Usually it says "Do not spray until after the 2nd or 3rd mowing.")
Insects interfered. I may try this again.