Some of the larger summer vegetables can be planted from seed directly into the garden this month. These include watermelon, cantaloupe, corn, and summer and winter squash. They tend to have larger seeds, and a rule of thumb is to plant them at a depth of two to three times the diameter of the seed. If you have a seed packet, follow instructions for planting depth, spacing, and thinning. These larger plants tend to grow quickly and out of the reach of many pests that impact small, tender, young seedlings. Amend and thoroughly water the soil before planting so that the seeds are not washed away with watering. Drop the seeds in holes and cover them with soil, or push them down into the soil. Then water again. Keep a close eye on emerging seedlings and protect them from pests as needed.
More information: Planting Vegetable Seeds (Alameda County Master Gardeners)