Green Riyadh Program: 7.5 Million Trees and Urban Canopy Transformation

The Green Riyadh program represents one of the most ambitious urban greening initiatives ever undertaken in an arid climate — a comprehensive effort to plant 7.5 million trees, develop 1,100 new parks, and expand the city’s green coverage from less than 2 percent to approximately 9 percent of the metropolitan area. In a city where summer temperatures routinely exceed 45 degrees Celsius, where rainfall averages barely 100 millimeters per year, and where the urban landscape has historically been dominated by concrete, asphalt, and bare earth, the transformation envisioned by Green Riyadh is nothing short of revolutionary. The program directly supports the quality of life that the Kingdom seeks to offer its citizens under Vision 2030 and provides the environmental context within which Expo 2030 visitors will experience the city.

Program Genesis and Strategic Context

The Green Riyadh program was announced as one of four major Riyadh development projects by King Salman in March 2019, alongside King Salman Park, the Sports Boulevard, and the Riyadh Art program. The program responds to a convergence of environmental, social, and economic imperatives that make urban greening essential rather than optional for the city’s future.

The environmental imperative is most immediate. Riyadh’s urban heat island effect — the phenomenon by which built-up areas experience significantly higher temperatures than surrounding rural areas due to heat absorption and retention by buildings, roads, and other hard surfaces — adds an estimated 3 to 6 degrees Celsius to the city’s already extreme summer temperatures. This heat amplification increases energy consumption for air conditioning, degrades outdoor air quality through ozone formation, creates public health risks including heat stroke and cardiovascular stress, and limits the hours during which outdoor activity is feasible.

Research from cities with comparable climate challenges demonstrates that strategic tree planting and green infrastructure can measurably reduce the urban heat island effect. Studies in Phoenix, Arizona, and Abu Dhabi, UAE, have documented temperature reductions of 2 to 5 degrees Celsius in areas with mature tree canopy coverage compared to adjacent unshaded areas. The Green Riyadh program is designed to achieve comparable reductions across the metropolitan area, creating more livable conditions for the city’s 8 million residents.

The social imperative reflects the changing expectations of Riyadh’s population, particularly its large youth demographic. As Saudi society opens to new forms of recreation, social interaction, and cultural expression under Vision 2030, the demand for public spaces — parks, gardens, plazas, and promenades where people can gather, exercise, and enjoy the outdoors — has grown rapidly. Riyadh’s current provision of public green space, at approximately 1.7 square meters per capita, falls far below the World Health Organization’s recommended minimum of 9 square meters per capita and lags well behind peer cities in the Gulf and globally.

The 7.5 Million Tree Target

The headline target of 7.5 million trees represents a transformational increase in Riyadh’s tree population. The current tree count across the metropolitan area is estimated at approximately 1 to 2 million, concentrated primarily in private gardens, institutional grounds, and the limited existing park system. Adding 7.5 million trees more than quadruples the city’s tree population and creates a visible transformation of the urban landscape.

Species Selection

The species selection for the Green Riyadh program is guided by several criteria that balance aesthetic aspirations with ecological reality. Water efficiency is the primary constraint — in a city that depends on desalinated seawater and non-renewable groundwater for its water supply, mass tree planting must employ species that can thrive with minimal supplemental irrigation once established.

The program’s species palette includes several categories. Native species — plants that occur naturally in the Arabian Peninsula — are prioritized for their adaptation to local climate conditions, their minimal water requirements, and their ecological compatibility with local fauna. Key native species include the ghaf tree (Prosopis cineraria), which thrives in arid conditions with deep taproots that access groundwater; the sidr tree (Ziziphus spina-christi), which provides dense shade and drought tolerance; and various acacia species that are indigenous to the Najd Plateau.

The date palm (Phoenix dactylifera), while technically a cultivated rather than wild species in many areas, holds unique cultural significance in Saudi Arabia and features prominently in the planting program. Date palms provide vertical shade, cultural resonance, and the iconic silhouette that defines Arabian landscapes. The program specifies multiple date palm varieties, including both ornamental and fruit-producing cultivars.

Adapted species — non-native trees that have demonstrated success in comparable arid climates worldwide — supplement the native palette where specific aesthetic, functional, or diversity objectives require species not available in the native flora. These include Mediterranean species (olive trees, carob trees), Australian species (various eucalyptus species selected for arid tolerance), and other species with proven performance in Middle Eastern urban landscapes.

Planting Strategy

The planting strategy distributes the 7.5 million trees across multiple categories of urban space, each with different planting densities, species mixes, and maintenance regimes.

Street tree planting constitutes the largest single category, targeting the installation of trees along approximately 50,000 kilometers of roadway and pathway in the metropolitan area. Street trees provide shade for pedestrians and vehicles, reduce pavement temperatures, improve air quality in traffic corridors, and create visual amenity that enhances the streetscape. The planting density varies by road type: major arterials receive trees at 10-meter intervals on both sides, residential streets receive trees at 15-meter intervals, and pedestrian pathways receive trees at 8-meter intervals.

Park and garden planting provides the dense tree canopy that defines the 1,100 new parks. Park tree densities range from scattered individual specimens in open meadow parks to dense grove plantings in woodland-style parks. The density and species selection for each park is determined by its design concept, microclimate, soil conditions, and intended use.

Institutional planting targets schools, universities, hospitals, government buildings, and other institutional properties. These plantings serve both the specific institutions (providing shade for outdoor spaces, reducing building cooling loads, and improving the aesthetic environment) and the broader city (contributing to the overall canopy coverage target). Partnership agreements with institutional property owners facilitate planting on private and quasi-public land.

Highway and infrastructure corridor planting targets the significant land area associated with highway medians, shoulders, interchanges, and utility corridors. These areas, while not publicly accessible, contribute to the visual greening of the city and provide environmental benefits including dust reduction, noise attenuation, and wildlife corridor connectivity. The highway planting program is integrated with the Kingdom’s broader Saudi Green Initiative, which encompasses a national tree-planting commitment and regional environmental coordination through the Middle East Green Initiative — positioning Riyadh’s urban greening as the most visible component of a nationwide environmental strategy.

The 1,100 Parks Program

The creation of 1,100 new parks across the metropolitan area represents a fundamental transformation of Riyadh’s public realm. The park program encompasses a range of park types, from pocket parks of less than 0.5 hectares to major community parks of 10 hectares or more, distributed across the city to ensure that every neighborhood has access to quality public green space within a short walk.

Park Typology

The park program employs a typology that categorizes parks by size, function, and catchment area, ensuring a balanced distribution of different park types across the city.

Pocket parks (0.1 to 0.5 hectares) are small, intensively designed spaces inserted into the urban fabric at neighborhood scale. These parks provide immediate relief from the built environment — a shaded bench, a small garden, a water feature — within a few minutes’ walk of surrounding residences and workplaces. The program targets approximately 500 pocket parks distributed across the city’s residential districts.

Neighborhood parks (0.5 to 5 hectares) serve as community gathering spaces with facilities for recreation, exercise, and socializing. These parks typically include playground equipment, fitness stations, walking paths, seating areas, and landscape planting, providing the everyday amenities that support active, outdoor-oriented lifestyles. The program targets approximately 400 neighborhood parks.

Community parks (5 to 20 hectares) serve broader catchment areas and provide more extensive facilities, including sports courts and fields, event spaces, botanical collections, water features, and nature areas. These parks function as destination attractions that residents travel to for specific activities and events. The program targets approximately 150 community parks.

Regional parks (20 hectares and above) serve the entire metropolitan area and provide large-scale landscape experiences — extensive walking and cycling trails, natural areas, picnic grounds, and event lawns — that cannot be accommodated in smaller parks. King Salman Park, at 16 square kilometers, represents the ultimate expression of this category, but several additional regional parks are included in the program.

Park Design Standards

The Green Riyadh program establishes design standards that ensure consistent quality across the 1,100 parks while allowing design diversity that responds to local context. The standards address accessibility, safety, amenity provision, environmental performance, and aesthetic quality.

Accessibility standards require that all parks be accessible to people with disabilities, with paths, gradients, seating, and facilities designed to accommodate wheelchairs, mobility devices, and sensory impairments. Universal design principles are applied from the earliest stages of park design, ensuring that accessibility is integrated into the design concept rather than retrofitted as an afterthought.

Safety standards encompass both physical safety (addressing fall hazards, water safety, and equipment condition) and personal safety (addressing visibility, lighting, emergency access, and natural surveillance through design). The concept of Crime Prevention Through Environmental Design (CPTED) informs park layouts, ensuring that sightlines, lighting, and spatial organization create environments that feel safe and are demonstrably safe.

Water Management

The water management strategy for the Green Riyadh program addresses the fundamental tension between the aspiration for a green city and the reality of extreme water scarcity. The strategy employs a hierarchy of measures that minimize freshwater consumption while maximizing the growth and health of the planted landscape.

Treated sewage effluent (TSE) represents the primary water source for park and landscape irrigation. Riyadh’s wastewater treatment capacity has been expanded specifically to support the Green Riyadh program, with treated effluent meeting quality standards for irrigation use distributed through a dedicated network of pipes and storage facilities to parks and planting areas across the city.

Smart irrigation systems, equipped with soil moisture sensors, weather stations, and automated control algorithms, optimize water application to match actual plant needs rather than fixed schedules. These systems reduce water consumption by 30 to 50 percent compared to conventional timer-based irrigation, ensuring that plants receive sufficient water for healthy growth without wasteful over-application.

Drought-tolerant plant selection, as discussed above, reduces the fundamental water demand of the planted landscape. Species that thrive with 200 to 400 millimeters of annual water application (whether from rainfall or irrigation) are prioritized over species that require 600 millimeters or more, resulting in a landscape that is both beautiful and water-efficient.

Measurable Outcomes and Heat Reduction

The Green Riyadh program establishes quantifiable targets for environmental outcomes that can be monitored and reported. The primary environmental target — a measurable reduction in urban temperatures — is assessed through a network of weather monitoring stations distributed across the city, supplemented by satellite-based thermal imaging that maps surface temperatures at high spatial resolution.

The target for temperature reduction is ambitious: a 1.5 to 2 degree Celsius reduction in average urban surface temperatures, measured across the metropolitan area, by program completion. This target, while modest in absolute terms, represents a significant environmental improvement that translates into reduced energy consumption, improved outdoor comfort, and better public health outcomes.

Air quality improvement targets include reductions in particulate matter (PM10 and PM2.5), ozone, and nitrogen dioxide concentrations attributable to the program’s greening activities. These reductions are measured through the city’s air quality monitoring network and validated against models that account for other factors affecting air quality (traffic patterns, industrial emissions, meteorological conditions).

The economic value of these environmental improvements — quantified through avoided energy costs, avoided healthcare costs, and enhanced property values — provides the financial justification for the program’s investment. Preliminary estimates suggest that the long-term economic benefits of the Green Riyadh program significantly exceed its costs, even before accounting for the social and quality-of-life benefits that are more difficult to monetize.

Integration with Riyadh’s Urban Transformation Portfolio

The Green Riyadh program does not operate in isolation but functions as an environmental layer that integrates with and enhances the city’s other major infrastructure investments. The Sports Boulevard, a 135-kilometer green corridor threading through the metropolitan area, incorporates approximately 200,000 trees from the Green Riyadh palette along its full length, creating a continuous canopy that demonstrates the program’s design principles at linear park scale. King Salman Park, spanning 16 square kilometers, serves as the most visible showcase of what intensive greening can achieve in an arid environment, with dense woodland plantings, irrigated meadows, and botanical collections that provide a living demonstration of the species and planting techniques being deployed across the broader program.

The Riyadh Metro system, now operational with 120 million passengers carried since launch and a daily capacity of 1.2 million, creates transit-oriented development corridors where Green Riyadh’s street tree planting is concentrated. The 85 metro stations serve as nodes of intensified greening, with each station surrounded by planted approaches, shaded pedestrian pathways, and pocket parks that make the transition from climate-controlled transit to outdoor walking as comfortable as possible. The planned Line 7, connecting Diriyah Gate to Qiddiya via King Salman Park and New Murabba, will extend this green transit integration to the next generation of metro infrastructure, with landscape specifications that embed Green Riyadh standards into the transit expansion program from the design phase.

The Expo 2030 campus, situated on a 6.5-square-kilometer site in northern Riyadh, represents the most concentrated application of Green Riyadh principles. The campus master plan incorporates passive cooling through strategic tree placement, shaded pedestrian corridors, and water features that create comfortable outdoor conditions during the October-to-March Expo season. The campus landscaping draws directly from the Green Riyadh species palette — native ghaf trees, date palms, and drought-tolerant ground covers — demonstrating to 40 million international visitors that urban greening in extreme arid climates is not only feasible but beautiful. The legacy conversion of the Expo site into a permanent mixed-use district will preserve and expand these green elements, creating a model sustainable neighborhood that embodies the environmental standards the Green Riyadh program is establishing across the entire metropolitan area.

The Green Riyadh program, in its ambition and its constraints, embodies the challenge and the opportunity of sustainable urban development in arid climates. The program demonstrates that even in the most inhospitable environments, cities can be greened, cooled, and humanized through determined investment, careful science, and the conviction that the quality of the urban environment is not a luxury but a necessity for human flourishing.