Naturally Ventilated Polyhouse - Doddaballapur, Karnataka

Doddaballapur sits on the Deccan plateau north of Bengaluru at around 880 metres above sea level, with a tropical wet-and-dry (savanna) climate. The elevation gives it mild, equable weather - summer highs rarely push past the low 30s°C and nights stay cool - which is exactly why this belt became one of India's leading centres for cut-flower cultivation. Annual rainfall is moderate at roughly 940 mm, concentrated in the months around the southwest and northeast monsoons, with October the wettest. On paper, it's good rose country.

The catch is the crop itself. Dutch roses grown for the cut-flower and export market are judged on long, straight stems, uniform bud size, and unblemished petals - a standard the open field simply can't hold. A single spell of rain spots the petals and spreads botrytis and black spot, humidity swings invite mildew, and stem quality drifts with every shift in the weather. A favourable climate gets you part of the way; it doesn't get you export grade.

The Structure

A 17,200 sqm Naturally Ventilated Polyhouse was installed to close that gap. At Doddaballapur's elevation, the base climate already does much of the temperature work, so an active fan-and-pad system isn't necessary - what Dutch roses need is a rain-free canopy, controlled humidity, and the consistency that turns good blooms into uniform, market-ready ones. An NVPH provides precisely this, and at this scale, without the running cost of mechanical climate control.

The ventilation was set along the site's prevailing wind line to keep air moving steadily through the structure, holding humidity in check and discouraging the fungal pressure that follows still, damp air - while sealing the crop off from direct rainfall through the wet months. Inside, 90,000 rose plants were established in soil across the protected area, a planting density built for sustained commercial cut-flower output.

The result is a controlled, year-round environment for Dutch roses - one that takes a region already suited to the crop and lifts it to the consistency and bloom quality the cut-flower market demands.