The cheapest garden is one grown from seed, but your garden would be short-lived this year if you delay planting until spring. The solution? Turn empty milk jugs into mini greenhouses. Slice the jugs in half, leaving a half inch uncut to serve as hinge. Poke holes for drainage and ventilation, then add a few inches of soil. Plant your seeds and leave the jugs outdoors as early as January. When seedlings emerge in spring, replant them once mature enough.