Celery is a kitchen staple that you may (or may not) be able to grow in your home garden.
I say “may not” because it has thwarted me the few times I have tried it. Not that the plants didn’t grow, they grew quite well, through the cooler months, but they grew outward, rather than upward, and the flavor was very strong. Before we learn from what I did wrong, let’s learn the truth about this challenging crop.
A misrepresented edible
Celery plants have been misrepresented in elementary schools across the country for decades. The part we eat is not a stem, and the stringy bits that get caught in your teeth are not all plant veins. The familiar stalks, which are so well suited to dips and fillings, are actually the plant’s petioles, or leaf stems. Some of the differences between a stem and a petiole are:
Some of the indigestible strings of celery fame are vascular tissue, This is why, if you place a celery stalk in a glass of dyed water, you can see the dye move up, through the xylem. [Kids love this stuff!] The other stringy bits, however, are living structural components, called collenchyma. The tissues that make up the collenchyma are able to absorb water and behave much like a stiff gel, to hold the plant upright.
The celery plant
Celery (Apium graveolens) got its name from the Latin for ‘aromatic bee favorite’. As an umbellifer, celery is cousin to carrots, fennel, cumin, caraway, celeriac, parsnips, dill, parsley, anise, and poison hemlock. Celery flowers attract many pollinators and other beneficial insects, such as hoverflies. There are actually three different types of celery, each grown for a distinct crop: petioles, leaves, or roots. The celery plant originated in marshland - very unlike my hot, dry California summers, and only slightly moist winters.
How celery grows
Celery is a cool weather plant. It grows best when temperatures are 55 to 70°F. Grown in summer, it will bolt, or go to seed. This is fine, if you want to harvest celery seed for your spice cabinet. It is also a good way to end up with celery plants throughout your foodscape. Once a celery plant has gone to seed, the petioles will become very tough. [You can still use them to make soup stock, however.] Celery plants can tolerate light frost, but not consecutive frosts. Celery is a biennial, grown as an annual.
How to grow celery
While you can start a new celery plant from the base of a store bought celery, you need to be aware that those plants are certified safe to eat, but they are not certified safe to grow. Installing a store bought celery plant in your garden may be fine, and it may introduce a destructive virus or bacteria that may take years to overcome. It’s your call. Of course, you can always delegate those store bought celeries to indoor containers…
Celery is grown from seed. Seeds should be started 8 to 10 weeks before your area’s last frost date. You can also direct sow seeds in late summer for a winter crop. In either case, seeds should be planted 1/4-inch deep. Some growers recommend soaking seeds overnight prior to planting, to speed germination. Be sure to harden off your seedlings before planting them outside. Seedlings should be spaced 10 to 12 inches apart in the garden, containers, or raised beds, once they are 6 inches tall. If you have a particularly bright window, celery can be grown on a windowsill.
Celery needs lots of sun and it is a heavy feeder. You can protect and feed plants as they grow by top dressing around the plants with aged compost. Once petioles begin to emerge, you need to tie them together, to force them to grow upright. Celery needs least one inch of water a week to grow those crispy petioles. And they should be fed every 10 to 14 days. As the plants grow, gently build up soil around the plants, keeping the leaves exposed. This blanches, or etiolates, the stalks, by blocking light from reaching the chlorophyll, making them turn pale green to white. This also help prevent bitterness. You can get a similar effect by wrapping plants with straw, heavy fabric, or cardboard tubes, the same way you would with cardoons, to halt photosynthesis. Be cautious when watering, after you have set up your planting method. Water that sits on leaves and stems can lead to rot and other problems.
Celery pests and diseases
Celery is susceptible to aster yellows, bacterial leafspot, Phytophthora tentaculata, blights, mosaic virus, fusarium wilt, pink rot, and crater rot. Aphids, armyworms, earwigs, leafminers, lygus bugs, carrot rust flies, nematodes, whiteflies, treehoppers, cutworms, and voles will all take a bite out of your celery plants. You can sprinkle your celery plants with diatomaceous earth, to reduce many of the pests.
Like peanuts, celery is known to cause allergic reactions in some people. Contrary to popular wishful thinking, eating celery is not a 'negative calorie' experience. Digesting that celery stalk does not use up more energy than it provides.
Finally, did you know that celery flowers and leaves were used as garlands for King Tut’s tomb, some 3,300 years ago? I didn’t, either.
You can grow a surprising amount of food in your own yard. Ask me how!