This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The Seakale (Crambe maritima) of commerce has been evolved by selection from the maritime plant that can be seen growing on the seashore. It is useless for edible purposes unless artificially treated, by compelling it to grow in the dark and thus inducing it to expend its stored forces in sending out, in an effort to find the light, a compacted growth which the darkness bleaches (fig. 492). The resulting product is an esculent with all the delicacy and with something of the flavour of the Asparagus, but at present nothing like so much in the public favour.
Seakale can be grown from seed sown in March, when it takes two years to form a mature "crown", or from "sets" obtained by cutting the roots into lengths of 3 to 4 in. and striking them, one end becoming the crown and the other the root. These sets are planted out in rows 15 in. apart with 10-in. spaces in the rows.
The planters should be cautioned to close the sets well at the bottom with the dibber.
A great many shoots will be sent up from each set; many of these will disappear naturally, but in some cases three or four will persist, and as one good crown is better than two or three medium or small ones, the crop should be gone over in the early days of July and "suckered" to single crowns.
Fig. 492. - Forced Seakale.
Seakale prefers light sandy land. Though fond of moisture, it will not do where the drainage is not good. Being a Crucifer, it is terribly subject to clubroot attack. The appearance of this disease is often the indication that water is held in the land and has soured it.
Seakale is grown for forcing and as natural. For the former, the sets planted as above described are fit for lifting as soon as the foliage has died back in the autumn. The crowns are then taken up, the larger roots broken off to make sets for next year, and the crowns thus trimmed are laid either in sheds such as Rhubarb is forced in, or in beds under which hot-water pipes are laid, or around which manure is stacked. The heat given should be gentle and not too fierce. To get good results the process of forcing should take four weeks. Covering of mats and litter, supported by wooden framework and flaps, must be provided to ensure darkness and exclusion of air. When the growth is 8 to 9 in. long it is fit to cut. It is then sorted into best and seconds, and the most approved way of preparing for market is to tie it up in chip punnets each containing about 3 lb. weight, wrapping in blue paper for the best and white for the seconds. When it is plentiful it is sometimes sent up in half-sieves containing 12 lb. each.
Seakale is very tender and easily spoiled by frost, so that great care must be taken in handling and packing it during severe weather. The packing shed must be warmed, and plenty of newspaper and rough hay or straw used in the packing.
The price of seakale has come down very much of recent years. The average, which used to be 18s. per dozen punnets of best, is now under 12s. This means that all the processes in the production must be carefully scrutinized to save expenses if the result is not to be a loss to the grower. The expenses of cultivation may be set down as:
Sets, to cut and lay in, 6d. to 7d. per bushel; number of bushels required for an acre, 24. Planting, per acre, 27s. to 30s. Hoeing for the summer, £4 per acre. Suckering, 10s. per acre. Digging or ploughing out, 4d. per pole the first and 42s. per acre the second. Picking up and carting in, 20s. to 25s. per acre. Breaking off sets and laying in the crowns, about 60s. per acre.
This in addition to the preparations for planting, which will be on the ordinary scale and should include subsoiling. The cutting and packing will cost about 1s. per dozen for labour and 4d. per dozen for punnets> paper, and straw packing. An acre of well-grown, well-forced Seakale will produce about 80 dozen punnets, of which 70 dozen should be best.