Plant Swiss chard seeds 2 weeks before last frost date. Fill the container with soil to 1 inch below the rim. Make one row down the middle of the container and a row 3 1/2 inches away on each side of the middle row for a total of 3 rows in the container. Make rows 1/2 inch deep. Place the seeds about 1 inch apart in each row. Cover with soil.
Thin to 1 plant every 3 inches once the seedlings are 1 to 2 inches tall. 35 days to harvest for tender salad greens, 60 days for mature leaves.