Hoklartherm RIGA XL Professional GreenhouseHoklartherm RIGA XL Professional Greenhouse The Riga XL is the ultimate greenhouse for dedicated gardeners who need a year round greenhouse with a lot of work space. As the largest of the Riga line it is both wider and taller than other Riga models, and is available in several different lengths. Its 16mm triple walled polycarbonate glazing panels are also the most insulative of the Riga line, twice as thick as those of the Riga and Riga s. Like all