Trellising and training of greenhouse cucumbers
Trellising of cucumbers should not be confused with pruning. They do go hand in hand, but are very different. Trellising is leading the whole plant up the twine in a certain growth direction or pattern while pruning is removing leaves, fruit and growth points during the growth period. I suggest reading the article on pruning as well.
Vertical Training System (VTS) and Inclined Training System (ITS)
The vertical training system and inclined training systems use the same pruning procedures as URS and LMTS training systems. The plants are grown vertically upwards in double rows. The laterals are not allowed to move towards the rows parallel next to it. The ITS system does not use double rows but single rows instead. From the single row the plants are trellised in a “V” shape outwards. The width of the main trellising wire is the same as with the VTS system.
Guernsey Arch System (GAS)
The Guernsey Arch System (GAS) was developed in the Guernsey Islands (one of the Channel Islands). The GAS systems are not used commercially any more since it requires considerable experienced labour in order to maintain the arch.
The systems are as follows. The plants are planted in single or double rows with the rows 3.5-4.0 m apart. When using double row they should be aligned next to each other without any space in between. Preferable the plants should be planted in a “zigzag” manner to save space and improve ventilation. The height of the apex should be approximately 2.5 m. The skeleton of the arch is made from tubular piping forming the arch and wire running through the length. As one can visualise it forms an arched tunnel inside the greenhouse.
Plants are allowed to grow vertically up and over the arch. Some growers do not allow the growth of laterals but others do. The original system allowed the development of main laterals growing at right angles from the main stem. They are pinched to allow a maximum of two secondary laterals to grow at right angles out of the primary ones (parallel with the main stem). All fruit are removed from the main stem. The fruit that develop from the primary laterals are left to harvest.
Since the stems or laterals hang on the arch, no further training is required. The development of additional side shoots should be pruned and old leaves and crooked fruit should also be removed. Harvesting is easy. The fruit are very visible and accessible.
Arch Training Systems (ATS)
The Arch Training System allows for a single stem growing from one side of the path to the other. It allows for much higher in row spacing but the total plant population (planting density) per m2 stays the same. Horizontal wires are placed in the width of the greenhouse structure supported by cables running in the length of the greenhouse structure. The cables run over the paths. The plants are allowed to grow straight up the trellising twine as normal. When the main growth point reaches the main trellising wire it is allowed to grow over the path and down to the level of the bags on the other side. Side laterals are allowed to develop when the plant reaches the main trellising wire as in the URS system. Letting additional laterals grow will depend on climate and plant vigour. It is recommended that in the beginning only one stem is allowed to grow over the path and that there should be only one fruit for every two axils. Experiment with some plants allowing one fruit per axil and see if crooked fruit are formed. If not, the plant has enough vigour to carry the load.