Broccoli, a cool-season vegetable, thrives in both the spring and fall garden when temperatures aren't too warm. This frost-tolerant plant is one of the first harvested in spring if the seeds are planted and germinated indoors before outdoor planting, as this gives broccoli a head start on the gardening season. Unlike other vegetables, broccoli germinates best in cooler soils. Planting and caring for the seed properly ensures that most of the planted broccoli sprouts and grows to maturity.
Fill 3-inch diameter seed pots with potting soil. Leave a ½ inch space between the soil and the pot's rim.
Sow two broccoli seeds per pot, placing them on the soil surface. Cover the seeds with a 1/4-inch layer of fine-textured soil.
Fill a tray with water. Set the pots in the tray and leave them to absorb the water from the bottom. Drain the excess water out of the tray once the soil surface in the pots becomes moist.
Cover the pots with plastic wrap. Set them in a cool room that doesn't receive bright, direct sunlight. Broccoli germinate best at temperatures near 55 degrees F, according to the University of Missouri extension.
Remove the plastic wrap once the broccoli seeds germinate and sprouts emerge. Germination usually occurs within one week of sowing.