Fill a container that is at least 12 inches in diameter with a good quality potting soil. Put it in a spot that will receive full sun six to eight hours each day.
Saturate the potting soil by running a hose into the pot until water runs out the drainage hole.
Make planting holes with a pencil or screwdriver. Check your seed packet for suggestions on how deeply to plant seeds; generally, plant cucumber seeds about ¾ inch to 1 inch deep. Make your planting holes about 3 or 4 inches apart; you'll thin weaker plants, so don't worry about planting too many seeds or planting them too closely together.
Drop one seed into each planting hole and then water your pot again. Keep the soil surface moist until seeds sprout. After this happens, reduce watering to once or twice a week, depending on the weather. Water more often in hot weather and less when it is cool or rainy.
Thin seedlings to favor the strongest plants when they are 3 to 4 inches tall.