Celery is not really a root vegetable, but it has to be earthed up and later dug up. Celery was originally a British wild plant with poisonous properties growing in marshland close to the sea. Extensive plant breeding has removed much of the bitterness and celery is now a popular vegetable. It is known botanically as Apium graveolens duke (Umbelliferae). Celery grows best in a slightly acid soil which is deep, easily worked and has a high organic content. Adequate soil moisture must be available throughout the season, but the ground must not be water-logged. The main winter crops are grown in trenches. The self-blanching type is grown on the flat in blocks to exclude the brightest light but must be used before the onset of frost. It lacks the flavour and tenderness of the blanched celery but is nevertheless welcome and is useful for cooking.
Sow celery thinly in pots or boxes in heat in March for early varieties, or in a cold house in mid-April for the main crop. Prick off into deep seed boxes as soon as the seedlings are large enough to handle, at 2 inch intervals. After hardening off, plant out from mid May to the end of June, in prepared trenches. This is not only helpful in earthing but enables watering to be carried out by flooding the trench.
Prepare the trench some time before planting by removing soil 8-12 inches deep, depending on the situation. Placing the soil in equal amounts on either side of the trench. Keep the sides of the bank as upright as possible patting them with the back of the spade. This forms neat ridges on which lettuce. Spinach or radish may be grown. Place a good depth of manure in the trench and dig this into the bottom soil. Firm well by treading and leave the trench as long as possible to settle before planting. For single rows plant 10-12 inches apart, 12 inches each way for double rows staggering the plants. Immediately after planting flood the trench and repeat this operation in dry weather, feed occasionally with weak manure water or dried blood, and also apply two dressings of superphosphate at 1 oz per 6 foot run, by mid August.
Start to earth up when the plants are fully grown in August or September, after removing any sideshoots and low-growing leaves which would otherwise be com-pletely covered. Tie the stems with raffia and place soil from the side bank around the plants up to the base of the leaves. Slugs can cause much damage and it is wise to scatter slug bait round the plants before earthing up, especially if paper collars, black plastic or drainpipes are used, as they sometimes are, to ensure long, well-blanched stems. Pat the sides of the ridge to encourage rain to run down, rather than penetrate into the celery hearts. Celery fly can cause serious damage from May to September if pre-cautionary measures are not taken. Digging may begin six to eight weeks after earthing.
‘Clayworth Prize Pink’ produces a good crisp head. Good white varieties include ‘Sandringham White’ and Wright’s Giant White’. White varieties which need no earthing up include ‘Golden Self Blanching’ and ‘Tall Utah’.
Celery is another vegetable worth special treatment. For this seeds must be sown under glass in late winter or early spring, and grown on to produce good plants by June or July. It is best to sow in ordinary seed boxes, and to prick out the seedlings either into a frame of good soil, or into rather deeper boxes of soil, as the plants have a long season of growth under glass and should not be starved during that time.
PREPARING CELERY TRENCHES
Before the seedlings are ready for the open, the trenches should be prepared. Celery is a native of marshlands, and needs plenty of water during the summer. That is why it is grown in trenches, and the deeper and richer the trench prepared, the larger and better will be the crop, though as many a home gardener has discovered, small plants of very fine flavour can be grown in shallow trenches, where the larger trenches cannot well be made.
A 15 in. deep trench, with 4 in. of rotten manure or other humus, and 4 or 5 in. of soil over it is best. The remaining soil should be stacked at the trench sides, so that the trenches will actually appear to be somewhere about 1 ft. deep at planting time.
Plant firmly, in a double row if the trench is wide enough to allow for this, but allowing 1 ft. between the plants. Keep up the water supply, and when the plants are fully developed, which may be at any time after the middle of August according to the date of planting out, make a paper collar to each and tie it loosely in position. Then earth up in easy stages, say at weekly intervals, drawing a little more soil up against the collar each time. The purpose of the paper collar is to keep the stems as clean as possible, and to ensure that they are quite blanched, as green parts are not edible.
Celery is very liable to attacks of soil pests such as slugs, and soot dusted frequently along the rows is a useful insecticide and fertilizer. Liquid manure, preferably made from animal droppings, is very beneficial to the plants throughout the growing season.
More Information on Celery
Soil must be deeply dug and well manured. The usual practice is to prepare trenches either 15 or 18 in. wide, the former for single, the latter for double rows. If there is more than one such trench they must be at least 3 ft. apart. All soil is removed to a depth of 18 in. The bottom is broken up with a fork and manure or compost worked in. A layer 9 in. thick of good top-spit soil and manure in about equal parts is placed on top and then a further 6 in. of soil only.
Seed is sown in shallow boxes in February for an early crop or in March or early April for a later supply. First sowing should be made in a warm greenhouse, later ones in a frame. The seedlings are picked off as soon as they can be handled, and are spaced 2 in. apart each way. Plant out in June or July 1 ft. apart, down the middle of the trench in the narrow trenches or one row on each side in the wide ones. Water in very freely. Subsequently water liberally in dry weather, and give one or two light dressings of nitrate of soda at 1 oz. to 12 ft. of trench. Earthing up will be necessary with most varieties, but selftblanching celeries can be obtained. Work must not be started till plants_are fully grown. This will be between early September and the end of October. Remove offshoots round the base, tie stems together, and draw soil round them in a steep ridge. Celery is fit for use about six weeks after earthing up. It can be left in the open all the winter, and be dug as required, but it is advisable to protect the plants by placing two boards on edge along each ridge.
Varieties are Solid White and Standard Bearer.
The best of the selftblanching varieties is Golden Self
Blanching. This is particulary valuable for early use. Raise as ordinary celery but plant out on the flat, not in trenches. Ground should be rich and well dug. Space 9 in. apart each way and make a number of short rows rather than a few long ones. When well grown, place boards on edge round the bed to help blanch the outside plants.
Celery leaf miner and celery leaf spot are the worst foes. There is also a heart rot disease.