How to Grow Celery USA

At a Glance

Quick Facts

Factor	Value
Soil pH	5.8 - 6.8
Germination temp	59°F (15°C)
Optimal growing temp	64-77°F (18-25°C)
Minimum survivable temp	28°F (-2°C)
Time to harvest	70-84 days
Soil texture	RHS: "Fertile, moisture-retentive soil. Avoid sites where the soil dries out rapidly".
Drainage	RHS: moisture-retentive rather than free-draining, in a sunny spot. Utah State: "Full sun".
Lifecycle	biennial
Edible parts	stems (petioles)

When to plant in the USA

United States. Timing is set by temperature, not by the frost date. Start seed about eight weeks before planting out — Utah State suggests sowing around 1 February for an April to early-May transplant, depending on your area — and set plants out at 3-4 mature leaves. The reason to wait is bolting rather than frost damage: celery passes a juvenile stage at two to twenty leaves, after which two to twelve weeks at 35-48°F vernalises it and it runs to flower instead of thickening its stalks. Above 68°F that progress reverses. Plant out once cool spells are behind you, not merely once frost is. Harden off by withholding water rather than by chilling the plants — the usual cold-hardening routine is exactly what triggers bolting in this crop.

Soil & Growing Conditions

Water: RHS: a "Steady supply of moisture throughout the growing season"; the "soil should never be allowed to dry out". Utah State: "at least 1 to 2 inches of water from rainfall or irrigation each week".

Humidity: No published ambient-humidity range; RHS and Utah State both specify constant soil moisture instead ("soil should never be allowed to dry out"; 1-2in/week) as the operative requirement for celery.

Soil pH range

5.8 6.8

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Growth Stages

Stage	BBCH	Notes
Sowing & Establishment	0	Sow indoors mid-March to early April. PLANTING DEPTH & SPACING: surface-sow thinly on moist compost with only a very light dusting of sieved compost/vermiculite over the seed -- celery seed needs light to germinate and a minimum temperature of 59°F (15°C) (RHS), taking up to three weeks. Prick out and pot on seedlings once large enough to handle; harden off before planting out in late May to early June, once frost risk has passed and roughly 10-12 weeks after sowing (Utah State: 10-12 weeks to transplant). Space self-blanching/block plantings 23cm (9in) apart each way (RHS); space trench celery 30-45cm (12-18in) apart in a single row, or use 18-24in (46-61cm) row spacing per Utah State guidance. Never let young plants sit below about 10°C (50°F) for more than a few days once growing -- prolonged chilling triggers bolting (RHS).
Vegetative (Leaf Stalk) Growth	3	Plants build a rosette of leaf stalks. Celery has a small, shallow root system and forages poorly for water and nutrients (Utah State), so keep the soil constantly moist -- RHS: the soil "should never be allowed to dry out"; Utah State recommends at least 1-2in (25-50mm) of water a week from rainfall or irrigation. Mulch with 5cm+ of organic matter after planting to conserve moisture (RHS). Feed with a nitrogen-rich fertiliser about a month after planting to sustain leaf growth (Utah State). Any water stress at this stage causes stringy, strongly flavoured stalks later (Utah State).
Stalk Thickening & Blanching	4.1	Once self-blanching plants' stems reach about 30cm (1ft), tie or wrap the outer stems with newspaper or cardboard in mid-to-late summer to exclude light and sweeten the inner stalks (RHS); trench celery is instead earthed up gradually -- soil mounded around the stems in stages from late summer -- to blanch it (RHS). Continue steady watering and feeding, but stop nitrogen feeding once stalks begin to swell, to reduce the risk of splitting (Utah State). Protect self-blanching celery with fleece or cloches ahead of the first autumn frosts, as it is not hardy (RHS); earthed-up trench celery tolerates more cold and can stand later into autumn.
Maturation & Harvest	8	Self-blanching/green celery is ready mid-summer to autumn; trench celery matures later, from late autumn into early winter (RHS). Harvest as soon as it reaches the desired size and before outer leaves start to yellow (RHS) -- typically 70-84 days from transplanting. Utah State: pick outer petioles once a foot (30cm) or more long, or lift whole plants once 3in (7.6cm) or more in diameter. Dig up whole self-blanching plants for use since they do not store well in the ground; lift trench celery as needed through autumn/winter. Refrigerate harvested stalks for up to about 2 weeks (Utah State); RHS gives no specific storage method, reflecting best-used-fresh practice.

Harvest & Storage

When to pick: RHS: harvest "Once it reaches the desired size"; self-blanching types should be cut "before the leaves start to turn yellow". Utah State: "Harvest celery stalks by removal of the outer petioles when they are a foot or more in length. Whole plants are ready to use when they are 3 inches or more in diameter."

Storage

Utah State: "Store harvested celery in the refrigerator for up to 2 weeks". RHS states no storage method.

Diseases

Cucumber mosaic virus

Moderate to severe when it occurs -- RHS: causes stunting (shortened internodes), yellow mottling/mosaic, leaf curling and reduced yields; aphid-borne and erratic/unpredictable in occurrence (UC IPM).

Cucumber mosaic virus (CMV)

RHS names celery explicitly: "CMV also attacks spinach, lettuce and celery".

Celery leaf spot

High -- UC IPM/RHS: the most destructive foliar disease of celery; untreated infections coalesce, causing leaves to die and drop, giving stands a scorched appearance and reducing marketable yield.

Septoria apiicola

Pests

Celery leaf miner (celery fly)

Mainly aesthetic on established plants -- RHS: leaf blotching from mining, worse in the second (later-summer) generation which can stunt growth; chemical control not recommended.

Euleia heraclei

Carrot fly

Occasional/host-shared -- RHS lists celery among carrot fly hosts (carrot, parsnip, parsley, celeriac, celery) alongside carrot as the primary host; celery-specific severity is not separately rated by RHS.

Psila rosae

RHS: carrot fly affects "Carrot, parsnip, parsley, celeriac and celery".

Nutrient Issues

Boron (B)

deficiency

Correction

RHS symptom in celery: "Brown cracks in celery stalks". Boron is "less available in alkaline soils (above pH 7)". Correction: test soil pH and avoid liming already-alkaline soil; short term, fritted trace elements containing boron before sowing or planting.

Sources

1. Michigan State University Extension - Bolting in spring vegetables

   US extension source on the mechanism: celery has a juvenile period of two to twenty leaves, after which it vernalises when exposed to 35-48°F for two to twelve weeks; it devernalises above 68°F. Celery needs a larger plant and a longer exposure to vernalise than celeriac.

2. NC State Extension Gardener Plant Toolbox - Apium graveolens (Celery, Smallage, Wild Celery)
3. Texas A&M AgriLife Extension (Aggie Horticulture) - Celery (vegetable archives)

   US extension corroboration on frost/cold tolerance: young plants damaged near freezing; mature plants can withstand light frost but temperatures much below 30°F (-1°C) can kill/damage; used to correct an overstated 23°F (-5°C) survivable-minimum.

4. Utah State University Extension - Celery in the Garden
5. Utah State University Extension - Celery in the Garden (Fruit and Vegetable Guide Series)

   US extension source: planting window, 10-12wk to transplant, 18-24in spacing, small/shallow root system needing consistent nutrients, 1-2in/week water, N feed timing, stop feed once stalks form, refrigerate up to 2 weeks.

These 5 sources are specific to this region. The full list of 14 sources behind this guide (AHDB, EPPO Global Database, FAO EcoCrop and others) is in the references of our UK guide to celery; they describe the plant itself, which is the same wherever it grows.