Collection: Riverstone

Every greenhouse on this page is one structure, the Riverstone MONT, also listed as the Monticello: 8 feet wide, 8 feet long in its base form, and extendable in 4-foot sections up to 24 feet. The frame is heavy-duty extruded aluminum, electrostatically painted and guaranteed lead-free. The walls and roof are 8 mm twin-wall polycarbonate rated R 1.69, the panel to choose where winters are long and cold.

Inside, the peak is 7'6" and the side walls 4'10", and the lockable double doors give a 6' x 4' opening. One automatic roof vent comes with the 8-foot base and one more with each 4-foot extension, and the base anchors straight to the ground or to a foundation. Twist-and-lock fasteners and a ribbed frame interlock quickly, the tools needed come in the box, and assembly takes about two days. A dual rain gutter system is built in, and the doors and vents lock for extreme weather. It is made in the USA.

Four ways to buy it

• Greenhouse only: the structure with its automatic roof vents; 10-year manufacturer's warranty.
• Deluxe Kit, an option on the same page: adds a work bench system, a programmable watering system and shade cloth.
• Growers Package: light-diffusing panels that spread even light over the plants and block the view in from 8 inches away, a 17,000 BTU commercial heater with thermostat, electric ventilation, dual automatic roof vents, a work bench, and drip irrigation for up to 48 drippers on a programmable timer; 15-year warranty.
• Mojave Package: made for hot weather, with tinted roof and vent panels and a solar-powered ventilation system with a commercial fan and thermostat, so cooling adds nothing to the power bill; a work bench, a watering system and a sink are included; 10-year warranty.

Add-ons, now or later

The MONT accessories are sold separately, and the bench, watering system and shade cloth are ordered to match the greenhouse length. The range: a vented PVC work bench that holds up to 600 lbs, an automatic watering system with two weighted sprinkler heads and a digital timer, shade cloth that lets through 37% of the light, a greenhouse sink, extra automatic roof vents that start to open at around 68 to 72°F, and a 4' extension kit that goes on in under two hours.

New to growing under cover? Start with greenhouse growing for beginners, and compare other kits in Backyard Greenhouses.