When to plant celery?
Sow celery indoors, at not less than 15 °C, and plant it out in late May or early June, about 10 weeks later, without letting it sit below 10 °C for more than 12 hours. In Campania open ground runs from April to early July, with a transplant from late March, and in Sicily the written sowing is March-June or, in a mild climate, September-October.
When, by region
| North | Centre | South | |
|---|---|---|---|
| Sowing | Indoors, on the surface, because the seed needs light. Germination from at least 15 °C, up to 3 weeks. Then keep them above 10 °C. Outside about 10 weeks later, in late May or early June, once frost has passed. | Umbria's 2025 guide does not fix a month. No repeat crop: at least 2 years, and no other umbellifers. | In Campania open ground runs from April to early July. The summer cycle is transplanted from late March to early May; the winter one, in July, with a harvest in late January. In Sicily, March-June in a temperate climate and September-October in a mild one. |
| Spacing | In a block, about 23 cm each way. Trench varieties, in a row, at 30-45 cm. Below 10 °C for more than 12 hours, until the plant is settled, wait. | As in the north for the RHS. Umbria does not write a spacing. Nitrogen, if you follow that sheet, goes on in three doses: a third at planting, a third after about 1 month, a third after another month. | In Campania, rows 70-90 cm apart and 20-25 cm in the row, 4.4-7 plants per square metre. Under cover, up to 8-17. In Sicily, seed 2-3 cm deep, 30-35 cm in the row and 30-40 between rows. Growth at 15-25 °C. |
Cold while the plants are young sends them to flower. The soil must not dry out, or the stalks stay stringy.
15 °C (59 °F), 10 °C (50 °F), the 12 hours, the 10 weeks, late May or early June, 23 cm and 30-45 cm are from the RHS. April to early July, late March to early May, July with a harvest in late January, 70-90 cm, 20-25 cm and 4.4-7 plants per square metre are from Campania. Germination at 15-20 °C is from the same sheet. March-June, September-October, 2-3 cm, 30-35 cm, 30-40 and 15-25 °C are from Sicily. The 2 years with no other umbellifers, and nitrogen in three doses, are from Umbria 2025, which does not fix a month. Parsley, same family, is in when to plant parsley. The months are in the March calendar, April, May, June, July, September and October.
Warmth to sprout, then out late
The RHS sows indoors, on the surface, with a dusting of compost if you want: the seed germinates in the light. It needs at least 15 °C (59 °F). It can take up to 3 weeks. Once up, keep the seedlings above 10 °C (50 °F). Below that, they bolt later. Pot them into 7.5 cm (3 in) pots when they can be handled. Outside, about 10 weeks after sowing, in late May or early June, once frost has passed. If nights fall below 10 °C for more than 12 hours, wait. Then a cloche or fleece for a few weeks.
Plant in a block, about 23 cm (9 in) each way, so the stalks shade each other. Trench varieties, in a single row, at 30-45 cm (12-18 in). In mid to late summer, once the stalks are 30 cm (1 ft) tall, wrap the outer ones in paper, leaving the top third out. The pot method is in starting seeds indoors.
The southern months
In Campania the usual method is transplanting. Seedbed plants are ready in about 60-70 days, with 4-5 leaves. Open ground runs from April to early July. The summer-harvest cycle is transplanted between late March and early May, and cut from June. The winter-harvest cycle is transplanted in July and cut in late January. In a greenhouse or tunnel the cycle is autumn-winter or late winter to spring. Optimum germination is between 15 and 20 °C. From transplant to cutting, 80-150 days.
In Sicily the written sowing is in spring, March-June, in temperate climates, and in September-October in mild ones, for a winter harvest. Growth is happiest between 15 and 25 °C. Seed goes 2-3 cm deep, 30-35 cm in the row and 30-40 between rows. Transplant at 3-4 true leaves. Harvest, on the same sheet, comes 3-4 months after sowing for leaf celery and 3-5 months for the stalk type. Umbria, in 2025, sets no month. At least 2 years, and no other umbellifers. Parsley is in when to plant parsley.
Water all the time, or stringy stalks
The soil must not dry out. Short of water, the stalks do not swell and stay stringy, with too strong a flavour. Mulch after planting, clear of the stems. In a pot, water all summer, and feed every fortnight with a balanced liquid fertiliser. How much is in watering, and the pot in the container garden.
Green and self-blanching varieties are cut from mid-summer to autumn, before the first frost, and covered once nights turn cool. Trench celery, from late autumn to early winter. In crop rotation it sits with carrots and parsley. The RHS does not put it back where celery or celeriac grew for the past few years. Celery leaf miner and leaf spot are in pests and diseases.
In the app
Every plant in the catalogue has its own sowing calendar, and weather alerts for your area help you judge whether to sow now or hold off.
Frequently asked questions
When do I sow in the north?
Indoors, on the surface, at not less than 15 °C. The RHS does not write a sowing month: it writes the planting-out, in late May or early June, about 10 weeks later. Below 10 °C for more than 12 hours, until it is settled, wait.
What months does Campania write?
Open ground from April to early July. Summer cycle: transplant from late March to early May, harvest from June. Winter cycle: transplant in July, harvest in late January. Germination between 15 and 20 °C. Plants ready in 60-70 days.
What about Sicily and Umbria?
In Sicily, March-June in temperate climates and September-October in mild ones, at 15-25 °C, seed 2-3 cm deep. In Umbria no month is written: at least 2 years, and no other umbellifers.
How far apart?
The RHS: in a block, about 23 cm. Trench types, 30-45 cm. In Campania, rows 70-90 cm apart and 20-25 cm in the row. In Sicily, 30-35 cm in the row and 30-40 between rows.
Why are the stalks stringy?
Usually from drought. The RHS says the soil must not dry out, especially in warm weather. Cold while the plants are young, below 10 °C, sends them to flower instead.