The wild celery plant – from which cultivated varieties have been bred – grows on boggy riversides and marshy ground. This gives a clue to the conditions this popular salad vegetable needs – moisture-retentive soil that never dries out. So dig lots of garden compost into the growing site and be prepared to water regularly.
Instead, newer ‘self-blanching’ and green varieties are planted closer together in a block, to reduce the amount of light reaching the stems. For the best quality results though, you should still blanch those on the outside of the block, but this is more easily done by tying newspaper around them.
Celery is a classic salad vegetable, refreshing and crunchy. It can also be cooked in various ways, made into soup or added to stews, so it’s extremely versatile. Celery also very good for you – don’t be fooled by its high water content into thinking there’s nothing to it. It’s rich in nutrients, antioxidants and fibre, plus with barely any calories it’s a great healthy snack. And, of course, if you grow it yourself, it’ll be far fresher than shop-bought celery and packed with even more flavour and goodness.
Month by Month
Almost all the varieties of celery available today are self-blanching or green types, producing stems that are usually pale to mid-green, rather than white. Traditional ‘trench’ varieties, which require blanching (excluding light) to make the stems less bitter and paler, are rarely available, as they’re more time-consuming and tricky to grow successfully.
Different celery varieties mainly offer variations in plant size, sowing/harvesting times, hardiness and disease resistance. There are also a few varieties with red or pink stems.
For consistent crops of tasty, high-quality celery, it’s best to choose F1 hybrid varieties. Look too for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg for recommended varieties of celery and other crops.
You can also see many crops, including celery, in the veg plots at the RHS gardens, so do visit to see how they’re grown, compare different varieties and pick up useful tips and inspiration.
What and where to buy
Celery seeds are available in garden centres and from online gardening retailers. Almost all are the easier self-blanching or green varieties, however if you want traditional trench varieties, try larger seed retailers.
Young celery plants may be available in spring from similar sources, although the choice of varieties will be limited.
Preparing the Ground
If possible, prepare the growing site for your celery the previous autumn. Choose a sunny spot with fertile, moisture-retentive soil. Avoid sites where the soil dries out rapidly. Remove any weeds and dig in lots of well-rotted manure or garden compost, to improve moisture retention.
Just before planting, add a high potassium general fertiliser, such as Vitax Q4, at a rate of two handfuls per square metre/yard.
Although trench celery is rarely grown nowadays, if you want to grow a trench variety using the traditional method, dig a trench 40–50cm (16–20in) wide and 30cm (12in) deep. Then refill it to 10cm (4in) below the top with a mix of well-rotted manure or garden compost and soil. Leave the remaining excavated soil nearby, ready to mound up around the crop in summer to blanch it. Trench varieties can also be grown in a similar way to self-blanching types, using newspaper to blanch them instead of soil.
Celery seeds need warm temperatures to germinate and a long growing season, so it’s best to sow indoors to get them off to a strong, early start. They should then be transplanted outdoors after the last frost, into rich, damp soil.
If you don’t have the space to grow seedlings indoors, you can buy plug plants in late spring or early summer, ready for hardening off and transplanting outside.
Sow thinly and apply the merest of covering of fine vermiculite or sieved compost.
Place in a heated propagator or cover with a clear plastic bag and keep somewhere warm – seeds need at least 15°C (59°F) to germinate.
Germination can be slow (up to three weeks), so patience may be needed. Once seedlings appear, give them plenty of light, water them regularly and keep them above 10°C (50°F) – lower temperatures after germination can cause bolting (premature flowering) later.
Move the seedlings into individual 7.5cm (3in) pots or modules when large enough to handle, which might not be until several true leaves appear. Seedlings already in modular trays should be thinned to one per module.
Harden off young celery plants towards the end of May, gradually acclimatising them to conditions outdoors.
Then transplant them into prepared ground (see above) once all risk of frost has passed in your area – usually late May or early June. Young celery plants are sensitive to cold, so delay transplanting if necessary – temperatures mustn’t fall below 10°C (50°F) for longer than 12 hours until celery plants are well established.
Plant celery in a block rather than rows, spaced 23cm (9in) apart in each direction. Plants will then shade each other, which helps to blanch them.
You can also plant celery in a large container, at a similar spacing. Use multi-purpose compost and position it in a sunny, sheltered location. Just bear in mind that you will need water regularly and generously throughout the growing season.
If growing trench celery using the traditional method, plant in a single row in your prepared trench (see above), spacing plants 30–45cm (12–18in) apart.
Protect celery plants from slugs and snails
The key to success with celery is plenty of water throughout the growing season. If the soil dries out, the stems won’t swell and will be very stringy. Take care when tending celery, as it can cause a skin rash – it may be best to wear gloves and long sleeves.
When self-blanching and green celery is grown close together in a block, most plants don’t need blanching (excluding light to reduce bitterness). But it’s best to blanch the plants on the outside of the block. In late summer, tie a sleeve of newspaper or corrugated cardboard around them once they’re 30cm (1ft) tall, leaving the top third of the plant exposed.
If you’re growing trench celery using the traditional method, start mounding soil up around the stems (earthing up) in late summer to exclude light, gradually adding more as the stems grow taller. Alternatively, trench varieties can be blanched more easily with a newspaper or cardboard sleeve (see above).
Water regularly throughout the growing season, but especially during warm weather when celery plants will be growing fast and need lots of water. The soil should never be allowed to dry out. Celery can become stringy and too strongly flavoured if it goes short of water.
If growing celery in containers, be prepared to water daily in summer, as the potting compost will dry out rapidly. An automated drip irrigation system may be useful to ensure consistent watering.
Apply a thick layer of mulch, such as well-rotted manure or garden compost, around the plants to help hold moisture in the soil and deter weeds.
To boost growth, apply a light dressing of a high nitrogen fertiliser in summer, once the celery plants are established.
If growing celery in pots, feed every fortnight with a balanced liquid general fertiliser through the summer.
Weed regularly, especially around young plants, to reduce competition for water. It’s best to weed by hand close to celery plants, to avoid accidentally damaging the stems with a hoe blade.
Celery is ready to harvest once it reaches the desired size, from midsummer to autumn, and before the first hard frost:
Self-blanching and green varieties should be harvested as soon as they’re ready, before the leaves start to turn yellow, as they turn stringy with age. Most are not hardy, so cover with cloches or fleece once night temperatures start to fall and finish harvesting before the first frost
Traditional trench celery is ready from late autumn to early winter. Protect from harsh frosts with fleece
To harvest, dig up whole plants whenever needed. Use as soon as possible after harvesting, when crunchy, juicy and full of nutrients.
Celery is a versatile vegetable. Delicious raw, it’s great with dips or spread with cream cheese or even peanut butter. Chop it into salads or cooked dishes, such as stews, to add a refreshing crunch. It’s brilliant in smoothies too.
You can also cook celery – steam, braise or bake it, add it to stir-fries or make into creamy celery soup. And don’t discard the leaves – add them to salads or cooked dishes too.
Celery leaf miner
Celery leaf spot
Celery can be prone to bolting (flowering prematurely) if young plants are exposed to cold – ensure they stay above 10°C (50°F). Keep them indoors until late May or early June, harden off carefully, then protect with cloches or fleece for several weeks. Choose bolt-resistant varieties too.
Slugs and snails love celery, so take steps to deter or control them.
Celery can also be affected by celery leaf miner and celery leaf spot. To minimise problems, remove any leaves that have dry patches or spots, and avoid growing celery in soil where celery or its close relative celeriac have been grown in the past few years.
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