Celery

Celery requires full sun, at least six hours of direct sun, with some shade during heat spells. Plant in rich, well drained soil. Plan for 2‐3 plants per person.

Start seeds inside and under lights 10‐11 weeks before desired planting time. In Portland, that generally means mid February through May. Prepare the planting area by mixing in 3‐4” of compost in the soil, and add granular all‐purpose fertilizer to each planting hole. Plant transplants when night temperatures are regularly above 55°F in May and early June. If your plants are exposed to night temperatures below 55 for a week, they’ll probably bolt! Space plants 12” apart in rows 18‐24” apart. Cover new plantings with floating row cover to prevent carrot rust fly. To keep plants upright, work some soil up around them as they grow.

For whitened stalks, set a bottomless milk carton, paper bag, or similar device over plants to exclude light from stalks (leaves must have sunlight). Or grow self‐blanching varieties.

Mulch celery beds with 1‐2” of compost to help retain moisture.

How much water your plants will require depends on the soil and weather. Celery loves water and is accustomed to drawing large amounts of water from boggy areas, so do not let it dry out. If plants dry out, they may yield tough, stringy, dry stalks. Celery prefers drip or flood irrigation, or very good hand watering.

Celery is a heavy feeder, so fertilize every 3‐4 weeks with an all‐purpose granular or liquid fertilizer. Celery needs to grow quickly or it turns tough and bitter.

Most varieties will survive in the winter garden until spring. Mature plants are fine without frost protection down to the high teens. For continual summer and fall harvest, pick individual stalks as needed. If preferred, the entire bunch can be harvested at one time 100‐130 days after transplanting. Unopened flower buds and stems are also quite tasty. Celery stalks will turn limp soon after plucked from the garden. They can be refrigerated for up to a month or more, but are best left in the yard until ready to use. Wilted stalks can be refreshed by placing them in a tall glass of cold water.

Celeriac, a type of celery grown for its edible large root used to flavor soups, should be harvested after light fall frost to improve flavor. If you remove lower and lateral leaf shoots while the celeriac is growing, you will end up with a nice smooth crown. Dig up the crown, rinse well, and allow it to dry. It can be kept in a cool, dry, dark place for up to a couple of months.

Damping‐off occurs in cool, wet weather and prevents seedlings from emerging or causes seedlings to die off. Replant new seeds in an area with better drainage, or add more compost and wait for warmer weather.

Aphid damage often appears as curled, twisted, and/or yellowed leaves. You may find colonies of green to yellow aphids on the undersides of the leaves and growing tips. Sticky sap on leaves and stems, along white aphid skeletons, can be quite prevalent. There are numerous sprays and control measures to help combat aphids.

Flea beetles chew dozens of tiny holes in the leaves. For prevention, cover new seed beds with floating row cover until plants are 8” tall. Dust with diatomaceous earth or spray with pyrethrin.

Snails and slugs will chew the leaves or eat new transplants when they feed at night. They often leave iridescent trails on leaves and the ground. Slug baits and beer traps are just two ways to control them.

Carrot rust fly maggots will burrow into the heart and stunt or kill the plant. Cover new plantings with floating row cover to prevent the maggots. You can also apply beneficial nematodes to help control the maggot population. Do not store infected roots in the garden over the winter.

Early blight appears first as yellow spots on the outer leaves in late summer or early fall. These spots will then turn brown in wet weather, and brown streaks may appear in the stems. Spraying with Serenade or copper can help prevent the spread of the fungus. It is not related to blights of tomatoes and potatoes.

Late blight first appears as yellow spots on the leaves that turn to brown early in the season. If possible, remove all infected parts and spray with Serenade or copper to prevent the spread of the fungus. Be sure to remove all parts of the plant and roots when harvest is over.

Bacterial leaf spot starts as water soaked spots which turn bright yellow and eventually turn brown. It is a fungus that overwinters on celery debris left in the garden. Clearing out debris and using Serenade or copper can prevent the spread of this fungus.

Other pests and diseases include: Blackheart (a calcium deficiency), fusarium yellows (stunted yellow plants), mosaic virus (mottled leaves), loopers and armyworms (holes in leaves and green excrement among stalks), and tarnished plant bug (turns central leaves dark).