A hoop house is a greenhouse

Greenhouse

A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...

 with a plastic roof wrapped over flexible piping. The interior heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the structure. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall.

A US Department of Agriculture program is helping farmers install hoop houses. The program was announced at the US White House garden in December, 2009.

Farmers in Iraq

Iraq

Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

 are building these in increasing number and adding drip irrigation

Drip irrigation

Drip irrigation, also known as trickle irrigation or microirrigation or localized irrigation , is an irrigation method which saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves,...

to grow tomatoes.

Video

• USDA Promotes Hoop Houses at White House Garden Event Intro - http://www.youtube.com/watch?v=14jE1T2Vd_Q
• "Quick Garden Hoop" The Martha Stewart Show (Feb 18, 2010) - http://www.marthastewart.com/article/quick-hoop