Sow Apium graveolens dulce thinly in pots or boxes in oestrus in March for early change , or in a cold house in mid - April for the principal crop . Prick off into deep seed boxes as shortly as the seedlings are large enough to do by , at 5 cm ( 2 in ) interval . After hardening off , plant out from mid May to the destruction of June , in inclined trenches . This is not only helpful in earthing but enables lachrymation to be carried out by flooding the deep .
Prepare the trench some fourth dimension before engraft by remove soil 20 - 30 atomic number 96 ( 812 in ) deep , depending on the situation , set the soil in adequate amounts on either side of the trench . Keep the sides of the banking company as unsloped as potential patting them with the back of the spade . This forms bang-up ridges on which lettuce , spinach or Raphanus sativus longipinnatus can quite easily be grown . Place a honorable deepness ofmanurein the trench and dig this into the bottom soil . Firm well by treading and pull up stakes the trench as long as potential to settle before plant . For single rows flora 25 - 30 cm ( 10 - 12 in ) apart , 30 curium ( 12 in ) each manner for threefold row distribute the plants . forthwith after planting , floodlight the trench and recur this operation in dry weather . Feed on occasion with weak manure piss or dry blood , and also apply two dressings of superphosphate at 28 g ( 1 oz ) per 2 MB ( 6 ft ) run , by mid August .
take up to world up when the plants are amply grown in August or September , after removing any sideshoots and low - growing leaves which would otherwise be completely covered . Tie the stems with genus Raphia and place soil from the side savings bank around the works up to the base of the leaves . Slugs can cause much harm and it is wise to scatterslug decoy round the plants before earth up , especially if paper collar , black plastic or drainpipes are used , as they sometimes are , to see to it long , well - blanched stem . Pat the incline of the ridgepole to boost rain to run down , rather than perforate into thecelery heart . Celery fly can cause serious damage from May to September if precautional measure are not require . Digging may set about six to eight calendar week after earthing .
‘ Clayworth Prize Pink ’ produce a good crisp head . Good whitened varieties let in ‘ Sandringham White ’ and ‘ Wright ’s Giant White ’ . clean mixture which need no earthing up include ‘ gilded Self blench ’ and ‘ Tall Utah ’ .
