Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
What is Celery?
Celery (Apium graveolens) is actually a biennial plant that we grow as an annual. The original plants grew in the marshy areas of the Mediterranean so keeping your plants wet is key to your success.
There are three types of celery:
Stalk Celery – most popular in the US, this is the familiar celery that we see in the grocery store. It is sold in bunches, the pale green stalks tied closely together.
Leaf Celery (Apium graveolens var. rapaceum) – most popular in China, this is often sold to gardeners in the US as “cutting celery”. The stalks are thinner and have a stronger taste.
Celeriac (Apium graveolens var. secalinum) – most popular in Europe, it has a bulb like base, with a few thin stalks. It is the bulb that is used in cooking. It is also known as celery root.
I grow the stalk celery. Homegrown celery has more taste than the celery sold in the stores. Celery is also notorious for the amount of pesticides that are used to grow it commercially. Residues of up to 60 pesticides have been found on the stalks.
Commercially grown celery is grown in greenhouses so it is taller than the homegrown varieties. In your garden, the stalks will grow to about 18 inches tall. If you do not harvest your plants the first year, they will bloom and produce seed the second year. The flowers are white and grow in umbels similar to Queen Anne’s Lace to which it is related. The flowers produce the familiar celery seeds which are used dried as a flavoring. The leaves can also be used as a flavoring either fresh or dried.
How to Grow Celery
Celery needs full sun (8 – 10 hours per day) and lots of water. When planning your garden, try allowing for trenches that run between your rows of celery. This allows for water to be pooled to keep the soil moist continuously after watering. If celery is allowed to dry out between waterings, the stalks will be small and dry. You will need to provide regular watering during the growing season, a minimum of one inch per week. Don’t worry if you get a lot of rain. You cannot over water celery. It was originally a marsh plant so it grows best in wetter soils.
Your celery will need to be fertilized regularly. Compost is always my preferred fertilizer, but if you prefer commercial fertilizer a 5-10-10 is best for celery. Plan on fertilizing every 2 weeks.
If you have purchased plants for your garden, space them 12 – 14 inches apart in rows 2 – 3 feet apart. If you are watering and fertilizing regularly, your plants should be growing vigorously. If they aren’t growing vigorously after a few weeks, supplement your watering and fertilizing schedules with a good drenching with a fish emulsion liquid fertilizer to give them a little boost.
How to Grow Celery From Seed
Rather than buying plants, most gardeners grow their celery from seed. You can start your seed in either the spring or the fall. To decide which is better for your situation, celery has a total growing season of 130 to 140 days. That includes 125 days of cool weather.
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Starting Seeds in the Spring
Sow your seeds 10 – 12 weeks before your last frost after soaking them overnight. Soaking the seeds mimics the natural marsh environment in which celery originally grew. Surface sow the seeds in pre-moistened soil. Do not cover them with soil. They need light to germinate. Cover your containers with plastic bags to maintain the soil moisture and create a humid environment. Germination should occur in 7 days. The seeds germinate best in 70⁰F to 75⁰F temperatures. A heat mat will help keep your soil warm.
After germination, remove the plastic bag and mist your seedlings regularly to maintain humidity. You can transplant your seedlings outdoors when night time temperatures are consistently above 40⁰F. Space your seedlings 12 inches apart.
Starting Seeds in the Fall
Sow your seeds 10 – 12 weeks before your first frost. Follow the directions for spring seed starting except you will want to transplant your seedlings outdoors the first week in August provided night time temperatures have started to cool off. If they are still hot, wait a few weeks. Hot weather will cause your plants to bolt. Space your seedlings 12 inches apart.
How to Harvest Celery
There are two ways to harvest celery: either harvest individual stalks throughout the growing season or harvest the entire plant at once when mature.
Harvesting Individual Stalks
When your plants reach 8 inches tall, you can begin to harvest individual stalks. Cut stalks from the outside of the bunch about 1 to 2 inches above the ground. This will encourage the plant to produce more stalks for you to harvest later.
Harvesting the Entire Plant at Once
Celery is usually ready for harvest 90 days after you have planted the seedlings which you started indoors. Plants which have been growing all season outdoors develop dark green stalks which have a strong, sometimes bitter flavor, so most celery bunches are blanched before harvest to produce a mild flavor.
Blanching means preventing light from getting to the plant. This will cause the plant to lose chlorophyll which gives it its green color. Blanched plants are usually pale green or white.
To blanch your celery plants, about two weeks before you plan to harvest, tie a piece of twine tightly around the tops of your plants, similar to what you see in the grocery store. That will blanch the inner stalks. To blanch the outer stalks, after you have tied the tops, mound soil up around the outside of the bunch.
To harvest, cut the plants off at soil level using a sharp knife.
How to Store Celery
Celery stores very well. After harvest, store it in plastic bags in your refrigerator for up to 2 months. Or you can store it in your root cellar packed in sand like carrots for months. Celery can also be frozen. Use plastic bags designed for freezer storage and it will keep for months in the freezer.
© 2020 Caren White