Growing Celery

Growing Celery

​I always thought that growing celery (Apium graveolens) was difficult and required very moist conditions.  However, there are now wide varieties of celery, many of which are better adapted to drier growing conditions. One detail I learned after growing celery is that the bunches you buy at the store are the inner part of the plant. Celery also grows many outer ribs that are much narrower than the inner part of the celery. These outer ribs can be used just like regular celery. I like them in soups or stews, or I blanch and dehydrate them for celery powder.

Favorite Varieties

​Celery is one plant for which I prefer hybrid varieties over open-pollinated varieties. I have tried several open-pollinated varieties but found they do not grow as well and are more bitter than the hybrid varieties I have tried. One caveat is that I have not tried blanching celery (keeping the stalks in the dark during the growing season and before harvest), which is supposed to keep it less bitter. One of the first hybrid varieties I tried was Tango, and I had great success. It grew very well and is a faster-maturing variety at approximately 85 days. The next hybrid I tried is Kelvin, and since I have grown that variety, it is the only one I have grown. It is like Tango, vigorous and low maintenance, but I feel it does better with hot temperatures (please note, I live in Wisconsin, and my “hot” temperatures are nowhere close to what other parts of the country can hit) and lower moisture levels. It is also a faster-maturing variety at about 80 days. I use drip tape or soaker hoses connected to a timer throughout my garden, so this does help keep the soil evenly moist.

Starting Celery From Seed

​Celery is one of the first seeds I start, about ten weeks before the average last frost date, because it is slow to germinate and grow. Celery seeds require light to germinate, so gently press them into your seed-starting mix when sowing seeds. A heat mat can help germinate the seeds if your grow room is cool, 70-75°F is ideal. After the seeds germinate, you can remove them from the heat mat and keep them at 60-70°F. I start fertilizing with an all-purpose liquid fertilizer at 1/4 strength, once the seedlings get true leaves. You can transplant them to a larger pot when they have at least 2 true leaves, if you started them in smaller grow trays; I use 3.5” pots. Celery likes cooler weather, but cold temperatures can cause premature bolting, so keep them above 45°F when hardening them off. I transplant into my garden about a week after my average last frost date. 

Tiny celery seedlings soon after germination (center row).

Growing Celery

​Keep celery well-mulched to maximize soil moisture and control weeds. Using a timer-controlled irrigation system helps keep the soil consistently moist. Celery is a heavy feeder, so ensure your soil is healthy before planting. Compost or composted manure is a great addition to any soil. I also fertilize monthly throughout the growing season with a high-nitrogen fertilizer such as blood meal or fish emulsion.

Harvesting Celery

​The entire stalk (plant) of celery can be harvested when it is large enough for your use, or individual ribs can be removed as needed. I have found that if I leave celery in the garden all summer, the plants often start bolting closer to fall. If you want to collect celery seed, you can let some plants bolt. I find my growing season (zone 4b) is unfortunately too short to harvest seed.

A monster celery I harvested that measured 30 inches tall!

Celery Diseases

I have had some problems with celery growing misshapen and twisted with brown spots/streaks in the ribs. I have not had my celery tested for disease, but I believe it is either aster yellows, a disease caused by a phytoplasma, a bacteria-like organism, or leaf curl caused by anthracnose, a fungus. Aster yellows is transmitted by insects that feed on the celery plant. If you can stop the insect from feeding, you can control the disease, but once infected, there is no way to treat the plant. Since I am not sure whether I have a fungal disease or a phytoplasma disease, I do not treat my plants. Instead, when I find diseased plants, I pull them to prevent further spread, but I have never lost all my plants in a growing season.

Caution

​Very rarely, the foliage of celery and related plants (celeriac) can cause a reaction of the skin called photosensitivity or phytophotodermatitis.  Compounds in celery, called psoralens, can cause blistering of the skin following exposure to sunlight. This is mostly seen in workers who harvest celery due to the extended time they spend in contact with the vegetation. However, on sunny days, it may be best to wear long sleeves and gloves when handling celery.

Conclusion

​I highly recommend trying to grow celery in your garden. I was intimidated by growing celery because I thought it was something only commercial growers could reliably produce. But I find celery is one of the easier vegetables to grow in the garden, and it has been a staple in my garden from the first year I tried it.

References

1. Cox, Jeff. 1988. How to Grow Vegetables Organically. Artichokes, p. 107-111. Rodale Press, Inc.
2. Johnny’s Selected Seeds. Celery & Celeriac – Key Growing Information. https://www.johnnyseeds.com/growers-library/vegetables/celery-and-celeriac/celery-and-celeriac-key-growing-information.html
3. UMass Extension Vegetable Program. Celery, Anthracnose. 2020. https://ag.umass.edu/vegetable/fact-sheets/celery-anthracnose
4. University of Minnesota Extension. Fruit and Vegetable News. Leafhopper Watch: Hot Weather and Aster Yellows Risk. 2021. https://blog-fruit-vegetable-ipm.extension.umn.edu/2021/06/leafhopper-watch-hot-weather-and-aster.html
5. Finkelstein E, Afek U, Gross E, Aharoni N, Rosenberg L, Halevy S. An outbreak of phytophotodermatitis due to celery. Int J Dermatol. 1994 Feb;33(2):116-8. doi: 10.1111/j.1365-4362.1994.tb01539.x. PMID: 8157392.