I’ll admit, I hadn’t grown celery from seeds until 2020. I was motivated to expand my gardening knowledge by starting all my vegetables from seed, including some I hadn’t tried before. I’ve learned a lot from trial and error so I wanted to share my experience, because planting celery seeds isn’t like planting other vegetable seeds.
Celery seeds should be surface sown, meaning they are sprinkled on the surface of your soil or potting mix and kept moist until they sprout. Sow celery seeds 8 to 12 weeks before your average last frost date. Keep them under grow lights indoors until they are a few inches tall and after your last frost date and when night temperatures stay above 50°F (10°C). Transplant outdoors 6 to 10 inches apart.
Why You Should Grow Celery from Seed
Growing celery from seed, aside from being highly fulfilling, is a way to get great tasting organic celery harvested a few steps from your door. You really haven’t tasted celery until you’ve tasted it homegrown.
You also get a chance to grow many different varieties you can’t find at the nursery, like Giant Red celery or Tango celery – both super flavorful varieties.
Just keep in mind that homegrown celery stalks usually aren’t as thick as those in the grocery store, but their flavor is much more intense. And you can also eat the leaves! They’re great in salads or used in soups.
When to Plant Celery Seeds and Transplant Seedlings
For a vegetable that doesn’t produce fruit, it’s surprisingly slow-growing. Celery takes anywhere from 80 to 110 days to mature. Because of this, you should plant your celery seeds indoors 8 to 12 weeks before your average last frost date. However, you can plant them up to your last frost date if you have a long enough growing season and still get a harvest.
Transplant seedlings when they are a couple inches tall and after your last frost, when night temperatures stay above 50°F (10°C).
Planting Celery: From Seed to Transplant
Celery is one of the few vegetables whose seeds are surface sown. You don’t want to bury the seeds. Sprinkle them on the surface of moist potting mix and mist them with water. I like to use a small 3-inch pot, but you can sprinkle them in seed-starting cells. Keep them warm and moist under lights until they germinate, which could take up to two weeks. One trick I’ve used is to use a clear plastic cover over them to keep them from drying out.
Once they sprout, take off the plastic cover (if you’ve used one) and mist daily as the sprouts get established. You can use a fluorescent, compact fluorescent, or LED grow light, but celery seedlings are very heat sensitive and will wilt if they are too close to the light – yes, I’m speaking from experience.
After your celery seedlings grow their first true leaves (i.e. the leaves after the first two seed leaves), you can either thin them out to one plant per cell, or if you sprinkled them all in one pot, you can very carefully tease them out and transplant them into their own small pots. Water them well after you transplant to reduce transplant shock.
Once your last frost passes and nights remain above 50°F (10°C), seedlings that are a few inches tall with a few sets of true leaves can be transplanted. I like to harden off my celery seedlings by taking them outside a few hours a day for at least a few days to get them used to the outdoor conditions.
Transplant your celery seedlings 6 to 10 inches apart.