By mid-October the trees around Cambridge Common let go all at once, and every lawn in the neighborhood turns gold overnight. Talbots' Creative Gardening reads that calendar closely — mowing through the shoulder weeks, leaf cleanup, cutting beds back, edging and shrub trimming before the ground locks up. Beds get shaped with an eye on how they will look in April, not merely how they look this Saturday. Then the mowers return in spring and the yards pick up right where they left off, greener for the rest. It is lawn and garden work across Cambridge and the surrounding towns.