How to Grow Organic Celery?
FUN CELERY FACTS
- In temperate countries, many farmers may be growing celery for its seeds. The seeds are, in fact, a small fruit. These “seeds” yield a valuable volatile oil used in the perfume and pharmaceutical industries.
- Growing celery seeds as a source of calcium is regarded by many as an excellent alternative to animal products.
- In Homer’s Iliad, the horses of the Myrmidons graze on wild celery growing in the marshes of Troy.
WHEN TO PLANT CELERY
- As celery needs about 150 days to mature if planted by seed, in Northern climates it’s advisable to start indoors 70 to 90 days before your last expected frost date.
- Young celery is not toleratant to cold temperatures and any hint of frost will kill it. Older celery will survive temperatures down to about 30°F, but no lower.
- For Northern climates, purchase celery varieties that matures more quickly.
- In Southern climates, celery is often planted in the mid to late summer for a winter harvest.
- In Southern climates with long growing seasons, you can seed directly to your garden; in Northern areas, it is always advisable to start celery indoors.
- If transplanted to the outdoors too early in Northern climates, celery will bolt (go to seed).
- Growing celery works best at daytime temperatures of 60° to 85°F with nighttime temps at around 50°F.
WHERE TO PLANT
- Like most veggies, celery loves the sun, but if it’s hot in your area, make sure celery gets plenty of water.
- Celery will do OK if it has partial shade (definition: shade some of the day), but needs at about 6 hours of sunlight daily.
- For Northern climates, purchase celery that matures more quickly.
- As mentioned above, celery grows best at daytime temperatures of 60° to 85°F with nighttime temps at around 50°F.
- Celery prefers well-drained and a little bit sandy soil with plenty of organic matter (add compost if necessary), but will do OK in soils that are not optimally drained as celery is a descendant of swamp grasses.
PREPARING THE SOIL
- For growing the best quality of celery, your soil needs to be very fertile.
- First, make sure your soil’s pH balance is in the range of 5.5 to 7.0. If your soil is too acidic (low), add lime to the soil to bring it up. If it’s too high, sulphur will bring it down.
- Adequate amounts of Nitrogen, Phosphorus, and Potassium (N-P-K) are required for growing celery.
- Several good organic sources of these nutrients are compost, chicken or cow manure (composted), and grass and/or legume cover crops.
- Adding 1 to 2 inches per year is usually adequate (approx. 2 lbs. per 100 sq. ft.). Mix it down about 6 inches into the soil.
- Fish fertilizers (meal or emulsion) are excellent for celery as these fertilizers benefit plants with high water content.
- If your soil tests a bit too low in Potassium, wood ash (particularly hardwood ash) is a good source.
- Most soils will naturally contain enough micro-nutrients such as Boron, Manganese, and others. Liquid organic leaf spray fertilizers can also keep the levels of your micro-nutrients balanced, as do compost and composted manures.
- The soil should be loosened well by rototilling or spading then raking the surface until smooth.
- Celery has shallow root systems, so your nutrients don’t need to be any lower than 6 inches into the soil.
- They have small root systems and are poor foragers, so there needs to be a good supply of nutrients in the surface soil.
CHOOSING THE RIGHT SEED VARIETIES FOR YOUR AREA
- Disease-resistant seeds may be necessary if you have particular diseases in your area. Check with your county extension before ordering seeds.
- One major disease that attacks celery is “Fusarium Yellows.” Resistant yellow varieties include Michigan Golden, Michigan Green Gold, Cornell 19, Cornell 6, Morse’s Masterpiece, Florida Golden, Tall Golden Pascal, Plume, Golden 99, Golden Pascal, Emerson Pascal, and some strains of Wonderful.
- Some green varieties that are highly resistant to Fusarium are: Curly Leaf Easy Blanching, Pride of the Market, Full-heart Easy Blanching, Winter King, Autumn King, Woodruff’s Beauty, Sweetheart, Crispheart, Krispgreen, Holmes’ Crisp, Earligreen, and Newark Market.
SEEDS AND GERMINATION
- Celery seeds should be good up to 5 years if you store them properly in a cool, dry place.
- Celery seeds germinate best if pre-soaked in water at 60°F for 6-8 days. Change the water once or twice daily to make sure it is oxygenated.
- The seeds will germinate best between 70° to 75°F if you’re starting them indoors.
- It’ll take the celery shoots around 2 to 3 weeks to come up at optimal temperatures.
- Make sure the seeds have some light when you’ve planted them (don’t plant them too deep) as they require some light to germinate.
- Once the shoots appear, the best growing temps are about 55° to 70ºF. If they’re outdoors, make sure they get enough water to minimize stress or they’ll develop too much fiber.
- If you want to save seeds, you need to purchase heirloom seed varieties. Do be aware that the disease resistant varieties are typically hybrids, so you won’t be able to save any seeds from those plants.
- When celery bolts (goes to seed), allow the seed heads (umbels) to dry. Two or three plants should give you several years worth of celery unless you are seriously expanding your crop area next year.
- Hand-harvest the umbels (seed heads) by holding a bowl beneath the umbel and brushing the seeds off into the container.
- Gently blow into the bowl to remove the debris; the clean seeds will remain in the bowl.
- If the seeds need to be dried more, just place them in the sun for a day or two (don’t let them go over 90ºF).
GETTING STARTED INDOORS
- Use a good potting soil to germinate your seeds. Most potting soil is sterilized so you don’t start out with any diseases in your plants.
- Put your potting soil into flats with individual cells and sow several seeds per cell and cover with a quarter to half inch of soil.
- At 70° to 75°F your seeds should germinate in two to three weeks.
- Move them to a cool location (60° to 70°F) once the shoots are up and thin to 1 plant per cell.
TRANSPLANTING TO OUTDOORS
- In preparation for transplanting the celery starts into your garden, you’ll want to harden off (move your plants outdoors during the daytime) your plants.
- It’s best to make sure danger of frost is past…celery starts can survive a light frost, but why take the chance?
- If the days are going to be under 55°F for more than a week, don’t put them outdoors or they may bolt.
- You can also reduce your celery plant’s watering somewhat to aid your plants in hardening off.
- If the plants have 3 to 4 mature leaves and are 4 to 5 inches tall, with a well-established roots system, you’re ready to transplant the celery. This usually is within 8 to 10 weeks of your original planting.
- Optimal outdoor temps should range from about 65° – 75°F in the daytime to nighttime temps of 60° – 65°F.
- When all of the above are in line, you’re ready to transplant your celery.
- The easiest way to prep the rows is to dig a trench 3 to 4 inches deep.
- If you planted the celery in peat pots, cut off the bottoms and plant them in rows in your garden 6 to 12 inches apart in the rows and space the rows 24 to 30 inches apart.
- If you planted them in individually-celled trays, carefully remove the entire plant with soil intact and place in trench, quickly and gently packing the soil in around the roots.
- Irrigate immediately after planting to ensure a high survival rate and continue to keep the soil very moist for the first 3 weeks.
PLANTING SEEDS DIRECTLY TO YOUR GARDEN
- Direct planting isn’t recommended, but can be done in more Southern climates in the summer for a winter harvest.
- Just in case you do plant before the last frost date, use some floating row covers to cover the plants for the first couple of weeks.
- Plant seeds in rows about an inch apart. Space the rows 24 to 30 inches apart and cover with a quarter to a half an inch of soil.
- Once the celery plants are well-established (a couple inches tall), thin them out to 6 to 12 inchesapart.
- Blanching: wrap the celery stalks with paper or cardboard a couple weeks before harvest; it will help prevent the celery from becoming bitter-tasting.
- You can also blanch your celery by mounding dirt up against the stalks.
- If transplanted to the outdoors too early in Northern climates, celery will bolt (go to seed).
GROWING YOUR CELERY
- Celery plants may cause skin irritation in some people. If you find this to be the case for you, just wear protective clothing and cloth gloves.
- Sometimes celery will exhibit transverse cracking…this indicates a Boron deficiency (this is rare if you’re using compost and manure in your garden). Apply a Boron foliar spray such as Organic Garden Miracle™ to correct this problem.
- Too much potassium will cause the same issue and “brown checking.”
- If you have a calcium deficiency, it could cause “black heart;” black heart typically strikes when it gets too hot.
- Liming may help restore your soil’s calcium levels if your soil isn’t above pH balance of 7. Calcium chloride will also work if the pH is already high enough (15 lbs. per acre).
- Apply once weekly until the stress is past.
- Keep an eye on weeds, insects, and diseases, and about mid-season side-dress your celery with composted manure or compost – about 1 lb. per 25 feet.
- Jenny’s Tip: This past year we began experimenting with a liquid organic leaf spray fertilizer called Organic Garden Miracle™. It increases receptivity to light and air factors and during the photosynthesis process, actually increasing its own plant sugar production by up to 50% or more. The flavor improves (makes veggies and fruits sweeter), the size of the veggies are bigger, and the fruits (when applicable) are more plentiful.
MULCHING & WEEDING
- Black plastic can warm the soil before planting and will both help to control weeds and also maintain soil moisture.
- Compost or barley straw also are good mulches that’ll do somewhat the same task, but without the plastic.
- You’ll need to make sure you keep celery weed-free. Celery does not do well with too much competition.
- Hand-pull the weeds that are close to your celery, and if much too close, cut the weeds off in order not to disturb the plant’s roots.
- Too much hoeing will unnecessarily dry out the soil.
- Celery needs about 1 inch of water per week throughout the growing season.
- It is best to use drip irrigation with celery, but if you don’t have that option, water early in the day so that the plants can dry out by noon.
- Prior to harvest, increase your watering; this will make it so the celery is more tender and crisp at harvest time.
- If your soil get’s too dry, it can contribute to the calcium deficiency syndrome called “black heart.”
- Make sure when you water that you completely soak the soil at least 6 inches down.
- Over-watering can cause problems too such as pink rot or crater rot.
COMPANION PLANTING AND ROTATION CONSIDERATIONS
- Celery plays well with beans, cabbage family members, leeks, onions, spinach and tomatoes. It also likes flowers such as cosmos, daisies, and snapdragons.
- Beans/legumes are known to fix nitrogen in soil by taking it from the air and depositing it in the soil.
- Cabbage family members apparently stimulate growth in celery, and celery repels the white cabbage butterfly.
- Tomatoes deter some bugs away from celery, and they also provide some shade for celery.
- Leeks and onions stimulate celery’s growth, enhance its flavor, and attract good insects. Onions also help control rust flies, aphids, weevils, carrot flies, moles, fruit tree borers, and some nematodes.
- Celery is a shade plant to spinach and they grow well together.
- Flowers such as cosmos, daisies, and snapdragons provide shade and repel harmful insects.
- Celery doesn’t play well with Corn, Carrots, Potatoes, or Asters.
- Asters and corn transmit the Aster’s Yellows disease which stunts celery’s growth and ruins celery’s flavor.
- Carrots and potatoes release substances that slow down celery’s growth.
- Celery also benefits from following plants like lettuce, kale, and cabbages as these crops leave significant amounts of nitrogen in the soil.
WHEN TO HARVEST
- You can harvest celery whenever you like…it doesn’t need to be full-grown, although a 3 inch diameter is considered ready to harvest. You can also carefully remove a few outer stalks and leave the plant to continue growing.
- Plants should be compact without too much vacant space in the center of the celery stalk.
- Cut the celery at the soil line or lower.
- If time allows, don’t harvest celery during a hot spell as it may be bitter, stringy, and tough.
- After picking the celery, wash it in cold water and dry; refrigerate for up to 2 weeks.
- Make sure celery isn’t refrigerated near pungent foods like onions; it picks up the flavor quickly.
- Celery will store for 2 to 3 months if kept at 32°F and almost 100% humidity.
- Celery can be canned or pickled.
- Celery can be chopped,blanched and frozen.
PREVENTATIVE AND NATURAL SOLUTIONS TO COMMON PESTS AND PROBLEMS
- Snails and Slugs eat holes in leaves. If you use rough bark mulch or similar rough mulches it will discourage slugs and snails from approaching your celery.
- To rid your celery patch of slugs, sprinkle the slugs with table salt.
- Another pest is leaf hoppers. They’re typically about 1/8″ long to 1/2″ long and can be yellow, green, gray, or patterned.
- They feed on the sap of the leaves and if too numerous will stunt or kill your plants.
- Overhead irrigation can discourage these pests. Keeping your garden area clean after harvest also reduces areas where leaf hoppers can winter.
- Floating row covers have also been successfully employed to keep leaf hoppers at bay.
- Dust your plants with Diatomaceous Earth or spot treat with organic insecticidal soap.
- Plant grasses in areas where there are currently weeds; leaf hoppers aren’t fond of grass.
- A third pest is aphids. These are typically green or black, very small insects that suck moisture from plants.
- It is usually pretty obvious when you have an aphid infestation as the leaves curl up and die.
- The best way to control aphids is to introduce them to lady bugs.
- Another effective way is to spray them with water using a high-pressure spray nozzle.
- A third method is to use an organic insecticidal soap spray.
- Leaf miner larvae are yet another pest that literally mine the mesophyll from the leaves and stalks of celery.
- Parasitic wasps are effective against leaf miners.
- Also, avoid planting next to infected fields of lettuce near harvesting time.
- Organic Azadirachtin sprays (neem) are effective against leaf miners as well.
- Black Heart: causes the leaves at the center of your celery turn black or dark-colored.
- One of the problems with this ailment is that it happens gradually and isn’t noticeable until late in the season.
- It is always caused by a calcium deficiency which is, in turn, caused by a water deficiency.
- Usually it can be avoided by consistent watering, adding calcium and magnesium if necessary, and side dressing mid-season with compost, bone meal, blood meal, lime, or composted manure.
- Pink rot/crater rot: fungal diseases caused by too much moisture.
- Don’t overwater. Make sure there are adequate magnesium and calcium levels in your soil.
- Asters Yellows/Fusarium Yellows: usually spread to celery by leaf hoppers. This disease stunts the plants and causes them to turn yellow and at later stages causes the heart to turn brown and rot.
- Fusarium yellows will attack the roots and crowns more than the heart.
- Controlling leafhoppers will control these diseases.
- Row covers are effective in discouraging leaf hoppers from taking up residence in your garden.
- Also, remove weeds like dandelions where leaf hoppers hang out.
- There’s no cure for the yellows diseases, so prevention is the only cure. If you discover any yellows diseases, remove the plants and destroy immediately to prevent the spreading of this disease.
- Powdery Mildew: this disease initially begins on the outer leaves, but will spread to the entire plant.
- It thrives in moist environments and will rob your celery plants of their vigor and cause premature leaf dropping.
- The best prevention is to plant powdery mildew resistant varieties and water early in the day.
- Nutrients are removed from the plant by the fungus during infection and may result in a general decline in the growth and vigor of the plant.
- Celery Leaf Spot Blight: brown spots appear on the outer leaves and then spread to all the foliage, particularly in high humidity.
- First, don’t plant infected celery and also don’t water late in the day.
- Second, make sure your soil’s calcium and magnesium levels are where they’re supposed to be.
- Celery Mosaic Virus: this virus stunts celery plants and creates a flattened appearance. The leaflets tend to curl upwards and the foliage may turn yellow or bronze.
- The mosaic virus is spread primarily by aphids. To rid your garden of this virus, make sure you leave no celery (including wild celery and wild parsnips) in your garden area for about 3 months.