CA Civ Code Section 798.37

A homeowner may not be charged a fee for the entry, installation, hookup, or landscaping as a condition of tenancy except for an actual fee or cost imposed by a local governmental ordinance or requirement directly related to the occupancy of the specific site upon which the mobilehome is located and not incurred as a portion of the development of the mobilehome park as a whole. However, reasonable landscaping and maintenance requirements may be included in the park rules and regulations. The management may not require a homeowner or prospective homeowner to purchase, rent, or lease goods or services for landscaping, remodeling, or maintenance from any person, company, or corporation.