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.
When the new roots are seen coming through the surface of the soil it becomes necessary to add fresh compost to the mounds. An inch or so all over of a fairly rich gritty soil will be sufficient. Right through the period of growth this topdressing operation must be performed at fairly regular intervals. Some growers use in addition to the compost special stimulants in the shape of concentrated proprietary manures in small doses. Nitrate of soda is also used as a liquid manure at the rate of 1 oz. to 1 gall, of water, but only when the foliage shows any signs of turning yellow. Topdressing with fresh stable manure should be avoided, as the ammoniacal fumes may scorch the leaves and spoil the plants. Soot is used to give a deeper green to the leaves and fruits, but it should be used sparingty, as large quantities are likely to impart a bitter flavour to the Cucumbers.
When Cucumbers are planted from 2 to 3 ft. apart, the main stem is often allowed to reach the top before it is "stopped" by having the tip pinched out. Some, however, pinch it once or twice before it reaches the top, and all young fruits and flowers on the main stem are suppressed as they appear. This induces the quicker development of the "laterals" or side shoots. These are stopped, as a rule, at the second joint when a fruit has formed at the first joint. The sub-laterals, or shoots arising from the laterals, are stopped in the same way at the second joint if a fruit has formed. After this it is a matter of judgment as to whether further shoots shall be allowed to develop or to be suppressed, according to the state and strength of the plants and the time available to finish the crop. But as a rule market growers rarely allow fresh growth beyond the sub-laterals.
To be able to tie the shoots of Cucumbers quickly and well to the trellises requires some little practice and experience. It is necessary to have a tie at almost every joint, and the operator must take great care not to rub off or knock off the flowers from the tips of the small fruits, as this seems to have the effect of stunting their growth.
In Cucumber growing the syringe is frequently used, but especially in the morning, and in the afternoon when the ventilators are closed or nearly closed. A moist atmosphere, combined with genial warmth, are essential to healthy growth and rapid swelling of the fruits. The moisture is also the great check or antidote to attacks of Red Spider. If the atmosphere cannot be kept sufficiently humid with the syringe and the usual watering, it will be necessary to damp down the pathways and walls frequently, and dry currents of air must not be allowed to rush through the doors or ventilators. While too dry an atmosphere is bad, care must be taken, in rendering it humid, not to make the compost round the roots so sodden with water that the fresh air is driven out of it, and the decaying organic material in it becomes sour, and engenders the development of Eelworm at the roots and "spot" in the leaf.