In 1961, Bill and Eleanor Hayes founded Automatic Rain, an irrigation distributor based in Menlo Park, California. The Hayes family operated Automatic Rain for 38 years, acquiring various companies and launching additional full service locations.

In 1977, David Lange opened Mesa Sprinkler, a wholesale irrigation supply company Dave had founded while working in the irrigation industry. In 1997, after 20 successful years of running Mesa Sprinkler, he purchased Horizon Turf, which specialized in the sale and service of turf maintenance products and power equipment. This union of both turf equipment and irrigation under one roof was an innovation to the industry. Mesa Sprinkler and Horizon Turf were consolidated as Horizon in 1998.

In January 1999, Bill Hayes of Automatic Rain and Dave Lange of Horizon merged the two companies under the name Horizon. The newly merged Horizon immediately flourished and grew to one of the largest distributors of irrigation, equipment, lighting and fertilizer in the western United States with 40 locations in 8 states.

In October 2005, the Lange and Hayes families sold Horizon to Pool Corporation (NASDAQ/GSM:POOL). With headquarters in Covington, Louisiana Pool Corporation is the largest wholesale distributor of swimming pool supplies and related products. As of December 2007 POOL operates over 280 service centers in North America and Europe, through which it distributes more than 100,000 national brand and private label products to roughly 70,000 wholesale customers. See www.poolcorp.com for more information.

Horizon is headquartered in Phoenix, Arizona and offers one of the most extensive arrays of products in the industry, including vendors such as Rain Bird, Hunter, Irritrol, Exmark, and Monsanto.