Idea for Green House in Apartment

Here is the good idea of small Green house for people who don't have many spaces and budget for cactus green house.  You can adapt the idea with your home.

Cardón cactus - World's Largest Cactus

Cardón cactus or Pachycereus pringlei (official name) is the tallest cactus species in the world, with a maximum recorded height of 21 meters (70 feet) high and weigh up to 25 tons.  Cardón  grows very slowly and is long-live. Many specimens live well over 300 years. Therefore, Cardón is not the popular cactus and usually founded in the dessert more than in the green house.

Cardón is a species of cactus, native to northwestern Mexico in the states of Baja California,Baja California Sur, and Sonora. You can also find a similar species in the Canary Islands (Spain), Euphorbia canariensis also known as Cardón.  Don't be confused with the Saguaro  (Carnegiea gigantea).  Although Cardón and Saguaro look similar, they are different: most Saguaro are found in the Sonoran Desert and they have fewer ribs on the stems, in being more heavily branched from near to the base of the stem, and in the location of the blossoms. 

The cardón are especially spiny when they are smaller, protecting them from predators. As they grow older, many of the spines fall off and are not replaced. The lower trunks of older plants turn gray, and a cracked, woody bark makes them look like the thick legs of an elephant. Woody vertical ribs allow the columnar cactus to expand and contract like an accordion, storing the water it needs to survive in the arid conditions. These cacti have developed extensive, shallow root systems which quickly capture the brief, but torrential rains of the region. In order to support this great weight, the large cactus has an interior framework of hardwood vertical rods, lightweight, yet extremely strong, which act to stiffen the ribs. This amazingly tough hardwood skeleton has allowed the cardón to become the largest cactus species, able to thrive in the very harsh climate of the Baja California's Sonoran Desert.