How to Germinate Celery Indoors

Germinate celery seeds indoors to get an early start on the growing season.

Celery requires a long growing season. When you plan to grow celery in the garden, you need to germinate the seeds before the frost ends. Celery seeds are usually started in mid-February to give the seeds plenty of time to germinate. The celery seeds require warm soil temperatures, so the seed-starting containers need to be monitored carefully. Once the celery seeds germinate, you can transplant the seedlings outdoors after the threat of frost passes.

Things You'll Need

• Divided seed-starting containers
• Soilless seed starting mixture
• Spray bottle
• Vermiculite
• Grow lights

Instructions

1. Fill divided seed-starting containers with a soilless seed-starting mixture.

2. Place the seed-starting containers onto a tray.

3. Water the soil with a spray bottle to moisten it. Add more soil to the containers if it settles so that the containers remain full.

4. Start the celery seeds 12 weeks before the growing season. Follow the celery seed packet instructions for planting directions. If you do not have directions, sprinkle a pinch of the small seeds into each growing container cell.

5. Cover the celery seeds with a light layer of vermiculite. Water the soil daily so that it does not completely dry out.

6. Place the containers in a location away from drafts and direct heat. The seeds need a temperature of 60 degrees Fahrenheit to germinate.

7. Hang grow lights 2 to 4 inches above the celery seedlings. Keep the lights on the containers for 12 to 16 hours a day until you transplant them outdoors.

8. Prepare the celery seedlings for germination when the frost ends and the seedlings are 8 centimeters tall.

Tips & Warnings

• Purchase an electric heating mat for the containers to help keep the soil warm if you cannot provide a consistent 60 degree F temperature.

• Harden off the celery seeds before you transplant them outdoors. Place the trays outdoors for one to two hours on the first day in a location where the seedlings are protected from the wind. Increase the time the seedlings are outdoors in the sunlight by one hour until they are outdoors for a full day. Never leave the seedlings outdoors when frost is expected.

• Always empty the excess water in the seed trays to keep the roots from rotting.

References

• BBC Gardening guides: Growing Celery
• Cornell University: Celeriac
• University of Minnesota Extension: Starting Seeds Indoors