Trellises: vertical and overhead

A trellis does three jobs in Qatar: it keeps fruit off hot, damp ground, it improves airflow so fungal disease has less to work with, and it gives you shade underneath for leafy crops.

Two kinds

• Vertical trellis: a wall of netting, wire or poles. Best for cucumber, beans, cowpea, tomato and bitter gourd.
• Overhead trellis (an arbour): a flat roof about 1.8–2 m up that the vines climb and hang beneath. Best for heavy-fruited gourds such as bottle gourd. Fruit hangs straight and clean, and the shade underneath helps lettuce and herbs in spring.

Things to get right before you build

• Strength: a full vine with fruit is heavy and catches the wind like a sail. Sink posts at least 40–50 cm and brace them.
• Wind: the shamal will find the weakest point. Where you can, run the long face of the trellis along the wind rather than across it, or add a windbreak.
• Timing: put it up before planting; driving posts afterwards cuts the roots.
• Height: 1.8–2 m for most crops, so you can reach without a ladder.
• Heat: bare metal gets too hot to touch in summer and can scorch stems. Wood, bamboo, rope and plastic-coated mesh are kinder.
• Tying: with wide strips of cloth, not thin wire or twine that cuts into the stem.

Materials

The materials are usually easy to find at hardware shops, nurseries and markets: wooden poles or bamboo, galvanised pipe, welded steel mesh, plastic trellis netting, rope and cable ties. Welded mesh is cheap, strong and lasts for years.

Which crops

Trellis cucumber, green bean, cowpea, bottle gourd, bitter gourd and tomato. Pumpkin, watermelon and muskmelon sprawl on the ground and are better off with a thick mulch beneath them.