Sow chard at wide spacings to produce large leaves for cooking or much closer together for baby salad leaves. Don't sow too early, as plants sown in the cold tend to flower prematurely (bolt).  

FOR MATURE LEAVES: Make two sowings to supply large leaves throughout the year; one in mid-spring to crop in summer and fall, and one in midsummer to pick from fall to the following spring. Stretch a string across the bed and make a trench 1 in (2 cm) deep along it. Sow single seeds at 4 in (10 cm) intervals, cover with soil, water well, and label.  Space rows 15—18 in (38—45 cm) apart. Plants can be raised in cell trays, on a windowsill, or outdoors, for transplanting when 2 in (5 cm) tall. Sowing in cells will give your chard plants a head start for summer salads. Sow one seed 1 in (2 cm) deep in the center of each cell, then cover with potting mix. Water well. Transplant seedlings by holding the root ball or leaves rather than the stem. 

FOR BABY SALAD LEAVES: Between early spring and midsummer, sow successionally every 2-3 weeks into soil or large containers. Sow seeds 1 in (2 cm) deep, into single rows, spacing seeds roughly 2 in (5 cm) apart and rows 8 in (20 cm) apart; or sow into broad 6 in (15 cm) wide drills, spacing seeds roughly 2 in (5 cm) apart each way.