Midsummer in the Meadowlands is heavy air and flat light, and by ten o'clock the heat is standing on the pavement along Union Avenue. Jacks Lawn & Property Care starts long before that — mowing at the height a hot stretch calls for, trimming the ragged margins, edging drives and walks into a hard line, and taking the whole yard down in the spring and fall cleanups. East Rutherford ground holds water from the old marsh beneath it, so a lawn here can go from lush to stressed inside a week. Watching for that is half the work. The payoff is a property that looks even and unhurried, right through August.