Celery and celeriac are the same species, Apium graveolens, grown for three different parts of the plant. Celeriac swells into a round root, stalk celery gives thick stems and leaf celery gives leaves you cut as a herb. All three start from a seed that needs light to germinate and takes two to three weeks to come up. Sow in February or March and even the celeriac has time to finish before autumn.
Three crops from one species
Decide which one you want before you buy seed. The names overlap on seed packets, and the difference in growing time between the fastest and the slowest is three months.
| Type | What you harvest | Sowing indoors | Harvest | Difficulty |
|---|---|---|---|---|
| Celeriac (Apium graveolens var. rapaceum) | A round root 10-14 cm across | February to March | September to November | Hard |
| Celery, also called stalk celery (var. dulce) | Thick, juicy stems | February to April | July to October | Moderate |
| Leaf celery, also called cutting celery (var. secalinum) | Leaves and thin stems used as a herb | February to April | June to November | Easy |
If you want the white root for purée and soup, celeriac is the one, and it starts earliest of all. If you are after stems, choose stalk celery, for example 'Tall Utah 52/70' or 'Golden Self Blanching 2'. If the celery is only there to season food, leaf celery is enough, such as 'Gewone Snij'.
How to sow celery
Celery seed needs light to germinate. Soil on top of the seed stops it from starting. This is the most common reason a sowing fails, because most people cover seed with half a centimetre of soil out of habit.
Fill and water: Fill a seed tray with fine seed compost, level the surface and water it through before you sow. If you water after sowing, the seeds wash around.
Sow on the surface: Scatter the seed thinly on the soil and press it down lightly with a fingertip so it makes contact with the surface. Do not cover. To hold the moisture you can sift a thin layer of vermiculite over the top, no more than 0.2 cm, which still lets light through.
Keep it warm and moist: 15-20 °C and an evenly moist surface the whole time. A clear propagator lid or a plastic bag over the tray does the job, but lift it off for a while each day so it does not go mouldy.
Wait out germination: Reckon on 2-3 weeks, sometimes up to 4. Germination is uneven, so do not throw out the tray when the first seedlings appear.
Celeriac needs that whole long run-up. Sow it as late as April and the root rarely gets bigger than a golf ball before the frosts. There is more on early sowings in our article on starting seed indoors, and you will find seed among our vegetable seeds.
Potting on and planting out
When the seedling has 2-3 true leaves, move it to its own 6-8 cm pot of nutrient-rich compost. Keep the pots bright and slightly cooler, around 16 °C, so the plants stay compact instead of long and floppy. If you use grow lights, 12 hours a day is enough.
Harden the plants off outdoors over 7-10 days. Wait to plant out until night temperatures sit steadily around 12 °C, which in most of the UK and northern Europe means late May or early June. Celery is biennial, and a young plant that stands for long below 10 °C reads that as a winter having passed. It then flowers the same year instead of forming a root or stems.
Celeriac: 30 cm between plants, 50 cm between rows.
Stalk celery and leaf celery: 25 cm between plants, 40 cm between rows.
Planting depth: Set the plant so the base of the stems sits at soil level. Never bury the heart, because it will rot.
Soil, water and feeding
Celery is one of the few vegetables that cannot take a single proper dry spell. The bed should be deep, rich in organic matter and moisture-retentive, ideally one where you have dug in 5-10 litres of compost per square metre in spring.
Drought stress shows up in the harvest. Stalk celery that has been left dry turns stringy and bitter instead of juicy. Celeriac that has dried out stalls, and when it starts again it lays down a woody layer inside the root that stays there even after cooking. Water thoroughly twice a week, 15-20 litres per square metre, rather than a little every day. A 3-5 cm mulch of grass clippings keeps the soil moist between waterings.
The plant needs feeding all season. Give seaweed extract or chicken manure every three weeks from mid-June to the end of August.
Brown, hollow patches in the root
If you cut open a celeriac in October and find brown, hollow patches in the middle of the root, it is usually boron deficiency. Boron is a micronutrient the plant uses to build cell walls, and without it the tissue inside the root breaks down while the outside looks perfect. The same deficiency causes lengthwise cracks in the stems of stalk celery.
Two things make it worse. On light sandy soils boron is washed out by rain, and on heavily limed soil boron gets harder for the plant to take up once the pH rises above 7. So do not lime the bed where the celery is going, and give seaweed extract or a fertiliser containing micronutrients a couple of times over the summer instead.
A small, smooth cavity in the middle of a large root looks different and need not be boron deficiency. The reliable sign is the brown, disintegrating patches.
Expose the root instead of earthing up
Celeriac is not a taproot that grows downwards. Unlike parsnips, the swollen part is a thickened stem base that sits largely above ground, and that is where it wants to be. Earth soil up over it and you get fine roots all over the surface and more to peel away.
Do the opposite from mid-August, and repeat every other week until harvest. Pull the soil away carefully by hand so the top 3-4 cm of the root is clear, take off the outer leaves as they lie down flat, and cut off the side roots that stick out. What is left is a smooth root with the roots gathered at the base.
Harvest and storage
Celeriac is harvested from September to November, when the root measures 10-14 cm across. It takes a few degrees of frost in the ground and can stand until after the first frosty night. Twist off the leaves and cut away the fine roots at the base as soon as you lift it. If the fine roots stay on, they draw rot into the middle of the root over winter.
Stored dark at 0-5 °C in high humidity, the root keeps for 6-8 months as long as it does not dry out. It can be buried in damp sand or put in a perforated plastic bag in the fridge. Stalk celery is lifted whole with its roots and keeps for up to seven weeks at 0-2 °C. Leaf celery you cut as you go from June, and the surplus you dry or freeze.
Leaf celery when the celeriac came to nothing
If the roots stayed small or the plants ran to flower, leaf celery is the way back. It has no root that has to finish in time, so a sowing in April is enough, and you cut the outer leaves as you need them instead of waiting for a single harvest in October. The flavour is stronger than stalk celery, so a few leaves go a long way in a stock.
If it is the celery flavour you are after, lovage seeds are worth trying alongside. Lovage belongs to the same plant family, tastes like a concentrated celery and comes back as a perennial year after year, which saves you the whole indoor sowing. You will find it among our herb seeds, and in Grow Lovage we go through how to look after it.
Author: Emma Vogiatzi
Fact-checked by Erik Hoekstra
Last updated 2026-09-15