Some gardeners consider celery a difficult plant to grow in a home garden. The difficulty with celery lies in the long, cool growing season it requires. To grow celery successfully, start celery inside approximately 3 months before the last expected spring frost. Then transplant the celery plants outside to harvest before the heat of the summer begins. Select a sunny growing site with a rich, well-draining soil to produce a bountiful celery harvest in late spring or early summer.
Fill the small cup with warm water and soak the celery seeds overnight before planting.
Fill the seed-starting tray almost full with potting soil. Drain the seeds from the soaking water and plant the seeds 2 inches apart under 1/8 inch of potting soil. Spray the surface of the potting soil with the spray bottle immediately after planting.
Keep the potting soil evenly moist during germination. Place the seed tray under the grow light for several hours each day to provide light for the growing seedlings.
Fill the individual pots with potting soil and move each seedling to an individual pot when the seedlings are 2 inches tall. Continue to keep the soil evenly moist and provide several hours of sunlight every day.
Prepare the growing area outside approximately 1 week before the last expected spring frost. Use the garden spade to till the soil down to a depth of at least 12 inches. Add between 2 and 4 inches of compost to the top of the soil and work this into the soil completely with the garden spade.
Transplant the seedlings to the prepared growing area when the soil temperature is at least 60 degrees F and the seedlings are at least 4 inches high. Plant the seedlings 8 inches apart in rows that are 10 inches apart.
Water the transplanted seedlings generously and place between 2 and 3 inches of mulch around the seedlings to help conserve moisture in the soil.
Fertilize the seedlings by adding additional compost to the soil around the plants two to three times over the growing season. Work the compost into the soil completely with a small garden fork.
Harvest celery stalks when they are between 6 and 8 inches tall. Cut the outer stalks just above the soil level with the garden shears. Continue harvesting celery stalks as they grow to the mature size.