The gardens lie within Riverside County's Coachella Valley, part of the Colorado Desert ecosystem.

[2] The Moorten residence was named the Cactus Castle, and was originally built in Mediterranean style by photographer Stephen H. Willard (1894–1966).

[3] The Moortens collected many of their own specimen plants from Baja California, mainland Mexico, and as far south as Guatemala.

[4] The garden includes 3,000 examples of desert cacti and other desert plants,[5] grouped by geographic regions: Outdoor collections include: Agaves, Bombax, crested Cereus, Cardoon and Boojum trees, "arborescent candelabra Euphorbia", a two-story Pachypodium, thorned Caesalpinia and Bursera, and over a dozen Aloes of southern Africa and Madagascar.

"Cactarium" greenhouse collections include: cacti and succulents, with caudiciform species exhibiting thickened root crowns, many species of Asclepiads, Aztecia, Gymnocalycium, Alstromeria, Euphorbia, and Ferocactus, plus two fine examples of Welwitschia mirabilis from Namibian deserts.