Break up the top 6 to 8 inches of soil in a full-sun garden bed using a spade or hoe. Spread a 2-inch layer of compost over the top of the soil. Sprinkle 2 cups of balanced fertilizer, such as a 10-10-10 blend, over every 50 square feet of soil. Mix the compost and fertilizer into the loosened soil.
Smooth the surface of the bed with a rake. Place a small garden stake at 5-foot intervals along one edge of the bed to mark each row, and then install another row of stakes on the other end of the bed, opposite the first row. Stretch a length of twine between each pair of stakes to mark the row layout so you can keep the cantaloupes spaced properly and the rows straight during planting.
Sow the seeds 1/2 to 1 inch deep. Group three seeds together, and space each group 18 to 24 inches apart. Remove the stakes and twine after the seeds germinate.
Water the bed until the top 6 inches of soil feels moist. Irrigate the cantaloupes once or twice weekly, supplying 1 to 2 inches of water per week from watering or rainfall. Once the seeds germinate, spread a 2-inch layer of mulch over the bed to help retain the moisture in the soil.
Thin each group of cantaloupe seeds to the strongest plant once they grow their second set of leaves. The remaining plants should set about 2 feet apart in the row.
Pull weeds from between the cantaloupe plants and along the row at least once a week so they don't become established. Pull a hoe between the rows to break up the top layer of soil and uproot small weeds, if necessary. Cantaloupes smother out most weeds and cover the bed once the plants begin to sprawl.
Sprinkle 1 tablespoon of 21-0-0 fertilizer 6 inches away from each plant when the cantaloupe begins to send out vines. Water following application so the fertilizer soaks into the soil.
Monitor the cantaloupes for aphids, which can weaken plants and spread viral diseases. Rinse these pests off the foliage with a spray of water or spray them directly with a ready-to-use insecticidal soap. Repeat soap applications at three day intervals until the aphids are gone.
Harvest cantaloupes when the rind behind the tan netting turns yellow and after the cantaloupes begin to slip off the vine on their own. Cantaloupes don't continue to ripen after harvest, so only pick fully mature fruits.