Till the soil deeply -- at least the top 12 inches -- breaking up large clods of soil so that it is light and powdery.
Pour 3 inches of well-rotted manure onto the rutabaga bed and use a rototiller to combine it with the top 10 inches of soil. Rake the bed until it is smooth and level.
Plant each rutabaga seed 1/2 inch deep and 6 inches apart from one another. When planting more than one row, space the rows 30 inches apart. Cover the seed with soil but don't press the soil over the top of it. Water the bed carefully to avoid washing the seeds away. Keep the top 6 inches of soil moist while the rutabaga seeds germinate.
Give the rutabagas their first shot of fertilizer one month after planting. Side-dress the fertilizer to avoid burning the plants. Use a spade or hoe to dig a 2-inch deep trench, placed 3 inches alongside the row of rutabaga plants. Sprinkle 3 pounds of 5-10-10 fertilizer evenly along the bottom of the trench, fill it with soil and water it to a depth of 4 inches.
Lift the rutabagas out of the soil when they measure 3 to 5 inches in diameter. The foliage is typically 12 inches in height at this time. They can stay in the ground while the soil temperature remains above 24 degrees Fahrenheit, according to master gardener Steve Albert with the University of California at Berkeley extension college.