Growing Celery

Celery, known to the scientific world as “Apium Graveolens ” from the Apiaceae – family is related to carrots, fennel, parsley, parsnips, and hemlock. It originated in the Mediterranean and was used in cooking by the Romans and Greeks, as well as medicinally by the Chinese.

You may have heard the myth that celery is a “negative calorie” or “non-nutritious” food, however at 95% water and just 16 calories per 100 grams (or about six grams for the average stalk), celery is an excellent snack! One serving provides 3 carbohydrates and 1.6 grams of fiber, as well as vitamins A, C, and K1, calcium, folate, magnesium, phosphorus, potassium, and minimal sodium.

Today, celery is grown around the world for its edible stalks, leaves, and taproot, which are all consumed as vegetables. Celery seeds are also routinely ground and combined with salt to create “celery salt”, a common addition to many recipes.

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Start Growing Celery

In the United States, celery is considered a winter crop in southern regions, it’s grown as a summer crop in northern areas, and it’s treated as a vegetable to be grown in the fall in most other climates.

When and Where You Should Grow Celery

One important thing to remember about celery is that this is not a crop that will respond well in very cold temperatures. That said, in moderate climates, celery can be overwintered outdoors, but generally it is best to move any crops that you wish to keep inside. When it comes to sunlight, celery is one crop that will require “blanching,” or the act of placing a piece of material around the edible part of the plant in order to prevent the leaves and/or stalk from turning dark and becoming bitter.

Celery requires a great deal of food and water. As a very heavy feeder, it needs an equally heavy amount of water in order to ensure that all of the nutrients in the soil are made available to the plant. Still, celery requires very good soil drainage as well. Celery tends to grow quite well in a raised bed or container, and in these cases, as the amount of water for the crop needs to be increased, drainage becomes that much more important as well.

Raised beds are one way to provide an excellent drainage solution in an area of a garden that may struggle with stagnation. Container gardening can prove a challenge when it comes to drainage but as long as you make sure that all of your containers have large enough holes drilled at the bottom, drainage for your container garden shouldn’t be an issue. If you do choose to grow your celery in a container, be sure to stay away from unglazed clay pots, as they will absorb water from your plants, and celery is one vegetable that needs its soil to stay on the damp side.

Preparing a Bed

Celery requires rich, dense soil due to its heavy feeding needs. In order to enhance the nutrient quality of your soil, thoroughly mix a good amount of organic compost, peat moss or manure into the soil a few weeks prior to planting. If you do not have rich soil naturally present in your garden, you may wish to grow celery in a container (such as a ten-inch pot) or raised bed instead. Fill the container or bed with rich garden soil and plant your celery transplants within. Simply dig a hole just big enough for the root ball of your transplant, gently drop in the celery transplant root ball, and push the soil back around the plant to stabilize.

Remember to add plenty of water after planting, especially if you are growing within a container, as this will increase your plant’s watering needs. Also, remember to add wood chips or another natural compost around your transplanted celery to help feed the soil and replace depleted nutrients as your plant grows. For most types of celery, the ideal pH is between 6.0 and 7.5. Celery also requires higher amounts of calcium. Adding lime to the soil can help raise the pH, which will help your celery crop avoid diseases like black heart (keep reading to learn more about this disease).

Growing from Seeds

Growing celery from seeds greatly increases the variety of celery types available to you, as compared to growing celery from transplants. While some may find this process daunting, don’t be intimidated. Maintaining consistent moisture conditions and avoiding low temperatures is the key to successfully growing a crop of celery.

If you wish to harvest in late-summer, begin seeds indoors 10-12 weeks before the last expected spring frost. It is strongly suggested to always start your celery seeds indoors for the best results. We recommend you look up your expected frost dates using this tool.

Starting Indoors

Before planting, soak seeds overnight to encourage germination. Fill your seed starting container with a mixture of 50% compost and 50% sand. If using a flat, plant seeds in rows one inch apart. Cover with a half-inch layer of sand. Cover entire flat (or each individual seed pot) with damp sphagnum moss or burlap just until seeds begin to sprout. Seedlings can be transplanted to the main garden once they are well-established – at least three to four inches tall, but preferably closer to six inches in height. Remember to spend about ten days hardening off your plants before transplanting them outdoors permanently.

In order to get your seedlings growing, place the seed flat (or pots) in an area that receives plenty of bright, indirect light. Your seedlings need to be shaded from direct sunlight, but you will also want to ensure that the temperature remains 70-75 degrees (Fahrenheit) during the day and no colder than 60 degrees at night during the plants’ initial growing period. If starting in a flat, the seedlings will need to be moved to individual pots when they reach two inches tall. When time to transplant, the ideal outdoor temperature should be between 50-55 degrees (Fahrenheit). Avoid moving celery outdoors during unusually cold spells, or before the soil has reached at least 55 degrees, as celery can tend to “bolt” – or prematurely go to flower – in cold conditions

Growing from Starter Plants

When planting your celery transplants outdoors in your main garden, you’ll want to dig your holes just big enough for the celery transplant root ball. Space each hole 6 to 8 inches apart, and space the rows two to three feel apart. Only set the celery as deep as they grew in their pots. Finish by watering each transplant with compost tea.

Celery is often grown from transplants, which are small seedlings that you purchase ready-to-plant in your garden. You can also “overwinter” your own celery crop indoors, which will effectively allow you to produce your own celery transplants. This is accomplished by gently digging up the celery before the first frost and placing the root ball in a mason jar with a small amount of water. Keep the jar indoors during the winter. On the other hand, if you are in a region with mild winters, it is safe to overwinter your celery crop outdoors under a thick layer of wood chips. Either method will allow you to grow mature celery from your own seedlings the following spring.

Watering and Mulching

Celery is a heavy feeder. It is ideal to cover the tops of celery beds with wood chips or another organic material that will feed the soil as it decomposes, as well as prevent weeds.

Celery also needs a great deal of water. When planted within containers, celery’s watering needs an increase. As with all plants, excellent drainage is critical in order to avoid rot and other diseases.

Companion Planting for Celery

There are many vegetables listed as excellent companion plants for celery, including tomatoes, spinach, onions, and beans. In addition, members of the cabbage family benefit when planted near celery because the scent of the celery plant will repel certain insects that attack the cabbage!

Some flowers are ideal companions for the celery crop, as well. This list includes daisies and snapdragons. These flowers both repel predators, as well as attract helpful wasps, which eat other insects. Some herbs – such as thyme, sage, basil, and dill – are also beneficial to celery for this same reason.

Several vegetables are listed as poor companions for celery, as each is said to have a negative impact upon the growth of one or both crops. These include corn, Irish potatoes, carrots, parsley, and parsnip.

Common Pest and Diseases

Like many common vegetables, such as tomatoes and onions, celery is quite susceptible to bacterial blight, leaf spot, and soft rot. One disease that is quite damaging to celery is called “Black Heart”. Black heart refers to a physiological condition within the celery that causes the deterioration of the young leaves at the heart of the plant. The cause of black heart is calcium deficiency, and it is related to blossom-end rot in tomatoes and tip burn on lettuce.

Besides common bacterial diseases, celery is also prone to a host of fungal infections, including brown spot, downy mildew, anthracnose, early or late blight, and grey mold – just to name a few. The best cure is prevention. Do not plant celery in cold, moist soil. Ensure soil is well-drained and that moisture and temperature levels remain consistent.

In addition to the many bacterial, viral and fungal infections which celery can be known to contract, you will also need to protect your crop from harmful pests, including carrot rust flies, parsley worms, and nematodes. Root-knot nematodes are tiny creatures that may be impossible to see, but if you notice your celery has stunted growth or bumpy roots, you may have harmful root-knot nematodes. These can be prevented through crop rotation and laying a sheet of plastic over the soil in the summertime when the nematodes are most prevalent.

Harvesting and Storing Celery

Individual outer stalks may be picked as you need them. If you wish, cut the entire head of the celery at the base with a sharp blade whenever it appears mature. If desired, you may cover the celery with a thick blanket of straw to help keep your celery harvest through the first fall freezes. Harvested celery can be stored in a cool basement or similar location for several weeks, or even up to a few months, under the right conditions.

Saving Seeds

Celery is a biennial crop. “Biennial” means that the plant will not produce seeds or flower until its second year in the ground. Some varieties are grown as annuals.

While you may harvest the outermost edible celery stalks during the first year of the plant’s life, if you want to harvest celery seeds from your own crop, be sure not to cut through the center stalk, which is where the seed-containing flower will sprout from.

During the celery plant’s second year, from the central stalk, you will see an umbrella-shaped flower emerge, called an “umbel”. The umbel is made up of many small, white florets. Bees will pollinate these florets, which will then fall off to reveal developing seeds. Wait until the seeds turn dark in color and become dry and hard. They should fall from the plant easily. To minimize seed loss, bend the tip of the flower head into a paper bag and shake. The seeds will fall into the bag, which can be labeled for storage.

Alternatively, you may use a small mason jar with an airtight lid for the same purpose. Celery seeds may be stored for up to five years, and can also be used whole or freshly ground to bring a wonderful flavor to many recipes.

Best Variety of Celery for You

Yellow-leaf celery: also known as “self-blanching”; has a more mild taste, more tender and less stringy than green varieties

Green/Pascal celery: celery most typically grown in the United States; stalks are green, firm and lengthy

Cutting celery: bushy, aromatic, stronger flavor; often grown for leaves and seeds

Celeriac: grown for its knobby root, which is peeled and eaten cooked or raw

More specific types…

Amsterdam Seasoning: heirloom variety of cutting celery; sold in the herb section of stores
Chinese White: long, slender, hollow-stemmed Asian variety; strong flavor; heat-tolerant
“Conquistador”: Early-maturing Pascal variety
“Flora 55”: leaf variety, resistant to bolting
Golden Boy: self-blanching, nearly stringless variety
“Par Cel”: 18th Century heirloom leaf variety
Redventure: red-stalked variety
Safir: leaf type; taste described as peppery and crisp
Tango: popular self-blanching variety
Tendercrisp: large and flavorful green variety
Utah Tall: Pascal variety with long stalks
Ventura: standard type

Additional Tips for Growing Celery

Cracked stems or misshapen leaves can be indicative of a lack of boron in the soil. This can be remedied by treating plants with liquid seaweed extract every two weeks until the symptoms are gone.
If your celery stems are hollow or dry, increase the amount of water provided to your plant.
If you have planted for a late summer harvest, you can also enjoy a “second harvest” by starting another round of seedlings indoors in May or June. This will allow you to grow the celery throughout summer and harvest late in fall.