GROWING GREAT SALAD CROPS

The salad crops include:

1. Celery

2. Lettuce

Also included are endive, radish, tomatoes, cucumber, tender carrots, early salad potatoes, spring onions, chicory, celeriac, peas, beetroots and the various types of cress.

CELERY

There are several types of celery:

1. The self-blanching summer celeries which are white or green.

2. Traditional trench celery which may be white, pink or red.

VARIETIES

Self-Blanching Varieties

These varieties are milder-flavoured and less stringy than trench celery, and they are not hardy.

Golden Self-Blanching Low-growing and early-maturing. Crop in August.

Lathom Self-Blanching’ The hearts are tender and stringless.

Celebrity’ Possesses all the good qualities, with longer sticks.

Under glass these celeries may be cropped from June to Christmas.

Trench Varieties

Trench varieties are not as easy to grow, as trenching and earthing-up is time-consuming. They have the best flavour, but are the least hardy, and need very good protection against frost.

‘Giant White’ Tall, crisp and full of flavour.

Giant Pink’ The crisp stalks form a solid heart, and the pale pink sticks blanch easily.

Giant Red Strong-growing – the outer stalks are purplish, green, turning shell pink when blanched.

Soil

Celery needs a soil containing a high level of organic matter. (Commercially, the crop is grown on the peaty Fen soils, where it thrives.) On heavy soils (clay or silty clay loam) slugs can be a problem.

Trench Celery

Preparation of Trenches

This is done well before planting. Single rows in 300 – 380 mm (12 – 15 inch) wide trenches are usual in a garden; on a field scale these rows would be 130 – 160 cm (4 – 5 inch) apart. Take out soil to depth of the spade blade and cast up on each side. The base of trenches should be forked over, and ample well-rotted manure or compost added to a depth of 75 mm (3 inch). A dressing in the trench area of 68 gms/sq.m (2 oz/sq.yd) bone meal and 34 gms/sq.m (1 oz/sq.yd) each of sulphate of ammonia and sulphate of potash, mixed, is advisable. The soil is then returned to leave a trench c.75 mm (3 inch) deep.

Raising Plants

Thiram-treated seed should be sown early in March, in a temperature of 13CC, 55°F, in J. I. seed compost or a mixture of peat and sand. Plants should be pricked out into seed trays, 50 mm (2 inch) apart, in J.I.P. 1 or grown on in soil blocks; grow on and harden off in a cold frame. Keep moist at all times. The plants will need to be hardened off and will only need the lights on in very cold weather.

Planting

Lift with a good root ball; set plants at 300 mm (12 inch) spacing in the row, and water in.

Watering

Celery has a high water requirement and will benefit from regular watering in dry weather. Some liquid feeding can be given, but overfeeding, causing over-soft growth should be avoided.

Earthing Up

When the plants are well-grown, by the end of July or earlier if required, earthing-up may commence. A dry day should be chosen; all loose, dead or decayed leaves, and all side shoots should be removed. The operation can not be completed at one time, but will need three or four turns at approx. 14 day intervals. Celery takes about 6 weeks to blanch. Celery collars will help to keep loose earth out of the hearts. Great care must be taken to control slugs at all crop growth stages.

Trench Varieties

Solid White’ – White

Ivory White’

‘Giant Red’ – Red

‘Clayworth Pink’ – Pink

Self-Blanching – ‘Golden self-blanching1, ‘Lathom self-blanching’ and Green celery.

Green varieties of celery, which require no earthing up and are of American origin,.are-becoming better-known. Plants are set out at 200 – 250 mm x 200 – 250 mm (8° x 8 to 10 inch x 10 inch) spacing (not in trenches) e.g. ‘Green Pascal’ and ‘American Green’. These are hardy varieties and should not be confused with ‘Golden self-blanching’.

NOTE: ‘Golden self-blanching’ is grown in frames or blocks outdoors for July – September use. It is grown at 225 mm (9 inch) spacing and is not earthed. It is not winter-hardy. Ample water, excellent soil conditions and ample top-dressings produce a fairly stringless celery stick which is very acceptable.

PESTS

Celery fly (Euleia heraclei), or Celery leaf miner Eggs are laid on the foliage in May and June and the larvae, once hatched, bore into the leaves to feed. Symptoms are mined tunnels and large blisters inside the leaves. In severe attacks the leaves shrivel and plants are checked. A second brood can cause further damage in July-August.

Spray with malathion, trichlorphon or dimethoate as soon as the mines or blisters are seen. Light attacks on established plants can be checked by crushing larvae and pupae within the mines.

Carrot willow aphid MAFF-approved products for the control of aphids on celery include dimethoate and malathion.

Slugs Damage from slugs can lead to soft rot, a bacterial disease which reduces tissues to a soft foul-smelling mush. Slug baits or draza pellets should be laid near the plants regularly.

Cutworms The turnip moth caterpillar is the most damaging of the cutworm group. It is grey-brown in colour with fine dark spots on the body, and feeds on leaves and stems, often severing the stem at ground level.

Thorough cultivation of the soil in winter months exposes the cutworms to weather and predator damage. Removing all weed growth removes egg-laying habitats. Young plants may be protected by applying insecticides such as bromophos or chlorpyrifos to the soil around the stems.

Celery leaf spot (septoria apilcola) Brown or black spots develop on the foliage and progress to the stalks. The disease is worse in damp weather.

The disease may be contained with one or two sprays of Benomyl. To eradicate the fungus, hot water treatment gives good suppression of the disease; however, a thiram seed soak is even more effective. Both methods, however, are difficult on a small scale.

LETTUCE

There are four main types of lettuce:

1. Round cabbage type – soft-leaved or butterhead.

2. Curly crisp types

3. Cos

4. Open-hearted, cut-leaved or loose leaf.

Open-hearted

The range of lettuces available has extended with the Lollo Rossa types with crisp frilly leaves tinged with a reddish-brown:-

Lollo Bionda – a pale green frilly lettuce;

Valeria – an intense red leafed frilly lettuce;

Carnival – an oak leaved lettuce.

Salad Bowl and Red Salad Bowl are two useful picking lettuces where the leaves are harvested individually rather than the whole plant.

CULTIVATION DETAILS FOR LETTUCE GROWN WITH PROTECTION FOR

SPRING CUTTING

Soil

Lettuce is very sensitive to acidity. The ideal pH is 6.8 for mineral soils, and 6.0 for peat soils.

Sowing

Seed is sown in October, in polythene tunnels or cold frames, usually directly into 38 mm peat blocks. Alternatively, . broadcast thinly and lift and transplant seedlings directly into the lights (or prick out first at 50 mm (2 inch) spacing, then lift and finally plant; or sow 150 seeds to a seed tray under glass and transplant 40 to a tray in J.I.P. 1 or into peat blocks.

Varieties

The selection of varieties is complex since there are so many varieties available. Some useful ones – ‘Salina, ‘Sonia’, ‘Avon Defiance’, ‘Helde’.

Manuring

A suitable base fertiliser dressing is 68 gms/sq.m (2 oz/sq.yd) superphosphate, 34 gms/sq.m (1 oz/sq.yd) sulphate of potash, or 102 gms/sq.m (3 oz/sq.yd) of a general fertiliser with an analysis of 7%N, 7%P, 7%K, e.g. Growmore or National Growmore.

Preparation for Planting

Polytunnels are left well-ventilated, or, if using cold frames, the lights are left off in autumn and early winter to obtain full benefit of rain, as it is important to have adequate moisture reserves in the soil before planting. Prior to planting, the lights are placed over the frames, so that surface soil dries out to allow it to be prepared to a fine tilth.

Planting Times A 38 nun square peat block

made of blocking peat,

This is done mainly in January. enriched with fertiliser

and pH balanced.

Planting

Spacing can be 200 nun (8 inch) or 125 mm (5 inch) by 200 mm (8 inch). The latter spacing gives 24 plants to a light if Dutch lights are used. A marker can be used to denote planting positions. Planting should be done from the back and front of the range of lights, I.e. the soil should not be trodden on within the lights. Plants are set shallowly and not very firmly. Peat blocks need only be placed in a shallow depression. Avoid damage to roots or stem when handling. Gap up any losses (I.e. replace any which have died). Guard against slugs.

The plant should be stood in a shallow depression (made …by a planting-machine). This raises the bottom leaves off the soil just enough to reduce risk of botrytis and helps to keep the lower leaves clean and marketable, I.e. they may not have to be trimmed prior to packing for market or consumption.

After Care

The lights are left on, but ventilation is given as the crop nears maturity or in warm spells in March. A feed with potash nitrate at 34 gms/sq.m (1 oz/sq.yd) is of benefit in March, especially if soil is not over-rich.

Watering

This should not be necessary on heavy soils, but may be needed on light soils. Watering should not be done in bright sunshine.

Cutting

The hearts are ‘tried’ lightly with the back of the hand and plants which are ready for consumption cut and handled with care. They are best cut in the early morning in cool conditions.

Pests and diseases

Aphids Spray with dimethoate/derris.

Slugs Good cultural hygiene, slug pellets.

Botrytis Spray with benlate.

Bacterial wilt Plants are less susceptible if grown in peat blocks and transplanted.

Bottom rot Careful handling and good growing conditions.

Downy mildew Good hygiene with crop residues. Improve ventilation and reduce the relative humidity.

Grey mould Improve ventilation and reduce relative

humidity.

Benlate

Lettuce mosaic virus Aphid control. Seed tests for LMV is available.

Big vein

(Olpidium

brassicae) A virus-like infection, carried from plant to plant by a soil-borne fungus. Every effort should be made to avoid introducing the disease since it may be very persistent.

Some control may be achieved by the application of specialist users pesticides. Rotation.

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