Why do polyhouse vegetable projects fail and lose money?

The honest reasons polyhouses fail are mostly not the structure, they are management and market. The common ones are: no proper buyer for premium produce so it sells at open field rates, poor climate and humidity control leading to fungal and viral outbreaks that wipe a crop, lack of training so the grower treats it like an open field, pest build-up especially thrips and viruses because the same crop is grown again and again, and underestimating running cost and labour. Many were also built just to capture the subsidy without a serious plan, and those almost always go idle. The structure lasts years but the film needs replacing every 3 to 4 years and that cost surprises people. A polyhouse is a skilled, intensive business, not a passive asset. If you cannot give it daily attention or do not have a reliable market, the failure risk is real. Visit two or three working and two failed units near you and ask owners directly before deciding.