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Green roof growing media: Types, ingredients, composition and properties.
Abstract and Figures
Although development of low (extensive) and high (intensive) maintenance green roof systems has progressed significantly, studies on the function of the growing substrate as a living constituent are lacking. The objective of this review paper is to summarize current
scientific knowledge on the components, composition, and characteristics of green roof substrates and to identify future research needs. Due to variations in climate and desired plant types, there is no universal growing substrate. An appropriate substrate is expected to
provide permanent physical support for plants and possess a fine balance between free drainage and adequate plant available water and
nutrient retention. Typical substrate components include minerals in natural or modified forms such as sand, lava rock, or expanded
shale, clay and slate; recycled waste materials like crushed bricks or tiles, crushed or aerated concrete and subsoil; stabilized organic
matter such as composts; and plastic materials and slow release fertilizers. Proportions of components vary among substrates based
on target vegetation, green roof type, and other considerations. Better green roof management for maximum benefits will require
characterizing, quantifying and understanding the impacts of plant species and building attributes such as aspect, slope, height and
heating on substrate performance, and should be considered for future research.
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... The vegetated roof's substrate layer has an awe-important role in providing the means for vegetation to grow and being the foundation of many regulatory services. The substrate is a mixture of different grain sizes and materials, increasing the roof thermal inertia and retaining and detaining water (AMPIM et al., 2010). ...
... Source: adapted by the author from Ampim et al. (2010). ...
... Right after, the substrate layer is commonly a mixture of different materials involving normally earth and soil and other aggregates for improving water retention, nutrition and drainage capacity (AMPIM et al., 2010). A mulching layer, consisting normally of dry organic matter such as decaying leaves or tree bark is indicated to help decrease substrate evaporation and nutrient washing, see Nagase, Dunnett and Choi (2013). ...
In densely built cities like São Paulo, where urbanisation has profoundly altered the
hydrological cycle, rainwater management becomes a concern. Soil waterproofing reduces infiltration, increases surface runoff, decreases evapotranspiration loss and increases the temperature of cities. Nature-based solutions have the potential to act on this scenario, managing rainwater close to where it precipitates. Extensive vegetated roofs stand out for compact cities within this range of Blue-Green Infrastructure possibilities. Where competition for ground land use is high, managing rainwater on top of roofs should be further explored. However, little is known about the hydrological performance of green roofs under the climate of São Paulo. In addition, few laboratory experiments with real-time data collection and robust instrumentation were performed in the city, demonstrating the gap in this scientific field. Thus, the present work aims to quantify the water performance of vegetated roofs correlating with its surrounding environmental conditions and, at the same time, investigate its vegetation dynamics, given the intimate interdependence between water, vegetation and heat. For this, built prototypes of an extensive vegetated roof and a ceramic tiled roof were instrumented, and new models with varying substrate depths were built, evaluating the comparative performance of these structures. Results show that ten years unmanaged vegetated roofs can retain 34 to 100% of rainwater and delay from
14 to 37 minutes and decrease the peak runoff by 30 to 100%. Spontaneous vegetation in laboratory models is also characterised, indicating that substrates with 10 cm may have optimal performance for the growth of Arachis repens species along with spontaneous vegetation, with some recurrent maintenance. The work demonstrates the correlation between the hydrological performance of the roof, its physical structure and its antecedent condition to the analysed rain events. Its water performance increases as its substrate depth increases and as its previous moisture decreases. It is concluded that the extensive vegetated roofs have a high capacity to retain incident rain and detain the resulting runoff, and at the same time generate habitat for a great diversity of species under the climate of São Paulo. It is expected that the work will contribute to the standardisation of these structures in Brazil and support their large-scale implementation through public policy based on scientific evidence.
... Intensive green roofs and extensive green roofs are the two major types of green roofs. Intensive green roofs generally demand high maintenance during their service life (Ampim et al., 2010). Meanwhile, the extensive green roofs that are called "substrate-based green roofs" can be constructed using lower depth substrates. ...
... Substrate (i.e. growing medium) is the most important component for the enhancement of stability and sustainability of extensive green roofs (Ampim et al., 2010). Green roof substrates are categorised into two main types: mineral substrates and organic substrates (Noya et al., 2017). ...
... In terms of mineral substrates, the naturally available topsoil, clay, pumice, sand, and gravel are used as substrates for green roofs due to their great ability to retain moisture (Kader, Jaufer, Shiromi, & Asmath, 2021). However, natural mineral-based growing mediums are hefty in weight, causing additional designs on the roof to maintain the structural stability of the structure (Ampim et al., 2010;Zejak et al., 2022). Lack of nutrients in these substrates persuades stakeholders to make additional investments in artificial fertilisers for efficient plant growth. ...
In twenty-first century buildings, green roof systems are envisioned as great solution for improving Environmental sustainability in urban ecosystems and it helps to mitigate various health hazards for humans due to climatic pollution. This study determines the feasibility of using five domestic organic wastes, including sawdust, wood bark, biochar, coir, and compost, as sustainable substrates for green roofs as compared to classical Sri Lankan base medium (fertiliser + potting mix) in terms of physicochemical and biological parameters associated with growing mediums. Comprehensive methodologies were devised to determine the thermal conductivity and electric conductivity of growing mediums. According to preliminary experimental results, the most suitable composition for green roof substrates comprised 60% organic waste and 40% base medium. Sawdust growing medium exhibited the highest moisture content and minimum density magnitudes. Biochar substrate was the best performing medium with the highest drought resistance and vegetation growth. The wood bark substrate had the highest thermal resistance. Growing mediums based on compost , sawdust, and coir produced the best results in terms of nitrate, phosphate, pH, and electric conductivity (EC) existence. This study provided a standard set of comprehensive comparison methodologies utilising physicochemical and biological properties required for substrate characterization. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements.
... Importance of green roofs in urban areas are increasing due to their ability to reduce the runoff ( (Ampim et al., 2010). Plants also signi cantly contribute to ecological cycle in the green roof system (Lundholm et al., 2010). ...
... Green roof growing substrates are generally a blend of natural and arti cial minerals, recycled or waste materials, and organic matter (Ampim et al., 2010;Young et al., 2014). Substrate materials could be produced from several sources by using several manufacturing techniques such as mining, heat-expansion, or any other energy demanded procedures. ...
Utilizing local resources and reducing environmental impact during green roof implementation is crucial to maintain the sustainable character of the green roofs. Green roof substrates constitute two main portions, which are organic and inorganic. Inorganic portions of the substrates are mainly responsible for the structural design of the substrate and the organic part handles the plant nutrition and water retention abilities. Therefore, a study was conducted to evaluate the usage potential of a waste material, rice hull, in organic and inorganic portions of the engineered green roof substrates along with vermicompost as a locally available organic material. Substrate blends are designated as RPZV, PZR, and PZV. RPZV blend consists of raw rice hulls 6:1; homogenous mixture of pumice and zeolite 2:1 and vermicompost 2:1 by volume. PZR blend consists of raw rice hulls 2:1 and homogenous mixture of pumice and zeolite with a ratio of 8:1 by volume. PZV blend, a mixture of homogenous mixture of pumice and zeolite 8:1 and vermicompost 2:1 by volume. Measurements such as plant growth index, chlorophyll fluorescence, biomass accumulation were performed on some native and exotic plant species including Allium schoenoprasum, Cistus creticus, Lampranthus spectabilis, Dianthus chinensis, Stachys thirkei, Sedum album and Sedum lydium . Findings of the study demonstrated that rice hulls have a potential to use in inorganic portion of the green roof substrates in due primarily to its low bulk density, lower salinity and resistance to degradation but have contrasting effects on substrate water retention when used as an organic part of the substrate. On the other hand, vermicompost amendment tend to hold larger volume of water, providing nutrients to the plant species but caused slight increase on EC levels of the substrate mixtures. Plant species tested in the study including A. schoenoprasum, C.creticus, L.spectabilis are good candidates for extensive green roofs in Mediterranean region.
... On the one hand, humidity-related metrics (wet-bulb temperature, heat index, equivalent temperature, etc.) can be incorporated into the evaluation system of green-blue space performance, instead of relying on air temperature and mean radiant temperature (Konarska et al., 2016;Ghazalli et al., 2018;. On the other hand, considering that high-density high-rise cities are easier to accumulate moisture in street canyons and tend to have less pedestrian-level space for green-blue infrastructure, green roofs and cool roofs can be utilized to maximize cooling effects and minimize in-canyon humidity effects (Ampim et al., 2010;Peng & Jim, 2015). In addition, ventilation strategies such as removing windbreaks can be combined with green-blue infrastructure for prolonged cooling distances and enhanced humidity dissipation effects (Hang et al., 2009;Peng et al., 2018). ...
Urbanization-induced atmospheric moisture changes, embodied as Urban Moisture Island (UMI) and Urban Dry Island (UDI) effects, are not as thoroughly understood as the Urban Heat Island (UHI) effects, despite their significant influence on human comfort and well-being. This paper offers the first systematic review and quantitative meta-analysis of global urban-rural humidity contrasts, aiming to advance our comprehension of the mechanisms, intensity, patterns, and implications of urban humidity changes. The meta-analysis compiles observational data from 34 studies across 33 cities. It reveals that mid-latitude cities predominantly exhibit moderate UMI and UDI effects, and cities with low mean annual precipitation and distinct dry/wet seasons, however, exhibit extreme UMI and UDI effects. The diurnal cycle analysis presents more pronounced UMI effects at night, largely due to increased evapotranspiration and delayed dewfall linked with UHI. On a seasonal scale, UDI effects dominate in spring, while UMI effects peak in winter for mid-latitude cities and in summer for low-latitude cities. In addition, city characteristics such as topography, morphology, and size significantly shape urban-rural humidity contrasts. Coastal cities are subject to sea-breeze circulation, importing moisture from sea to land, whereas mountainous cities can accumulate humidity and precipitation due to geographical barriers and vertical airflow. High-density urban areas generally experience heightened UMI effects due to restricted airflow and ventilation. Larger cities with higher populations contribute to increased UMI effects, particularly in winter, due to stronger anthropogenic moisture sources. This paper also discusses multi-dimensional humidity impacts and strategies for humidity-sensitive urban planning in the context of climate change. It identifies critical gaps in current research, paving the way for future exploration into urban humidity changes.
... These organic materials are not always available locally. It is therefore important to design and use locally produced growing media as this reduces the financial and energy costs of transport [52]. The incorporation of local waste materials is preferable as it transforms low-value materials into a valuable material, clearly lowering costs and helping to promote the implementation of green roofs. ...
Green roofs are artificial ecosystems that provide a nature-based solution to environmental problems such as climate change and the urban heat island effect by absorbing solar radiation and helping to alleviate urban environmental, economic, and social problems. Green roofs offer many benefits in terms of heat and water conservation as well as in terms of energy costs. This work proposes the design of an extensive and environmentally sustainable green roof for the Faculty of Engineering building in Bilbao. The green roof will be made from the composting of food waste generated in the building’s own canteen. Therefore, the main objective of this study is to calculate the solar efficiency of a sustainable green roof, evaluate its thermal performance, and quantify the impact that its implementation would have on energy consumption and the thermal comfort of its users. The results obtained confirm that an environmentally sustainable green roof has a positive effect on summer energy consumption and that this effect is much greater when there is water on the roof, as shown by the difference in energy savings between the dry (−53.7%) and wet (−84.2%) scenarios. The data show that in winter the differences between a green roof and a non-vegetated roof are not significant. In this case, the estimated energy consumption penalty (0.015 kWh/m2) would be 10% of the summer gain.
... Water availability can shift the nature of competitive/facilitative interactions between existing vegetation and spontaneous species [27,28]. Extensive green roofs can quickly become water limited, owing to freely draining substrates with low water retention [29,30] and high evaporative demand on rooftops [31]. Supplementary irrigation is often essential to establish vegetation on extensive green roofs, particularly in hot and dry climates [32,33]. ...
Lack of maintenance can lead to ‘weedy’ spontaneous vegetation on green roofs. Aspects of green roof design, including substrate depth and roof height, have been shown to influence the composition of spontaneous vegetation. In drier climates, Sedum species are often planted on shallow substrate ‘extensive’ green roofs and irrigated during summer to maintain cover. However, the response of spontaneous vegetation to Sedum cover and water availability is unclear. Understanding this relationship could help minimise maintenance and maintain Sedum vegetation cover. We hypothesised that increasing Sedum (Sedum mexicanum) cover and reduced water availability would reduce the abundance, biomass, species and functional richness, and the community weighted mean specific leaf area (SLA; CWM by abundance) of spontaneous plant communities. We conducted a 10-month experiment in green roof microcosms planted with S. mexicanum (0%, 25%, 50%, 75% and 100% total cover), subjected to a well-watered or water-deficit irrigation treatment, and sown with a mix of 14 plant species that commonly occur as spontaneous on green roofs. We measured spontaneous species abundance, community biomass, and functional traits (specific leaf area, leaf dry matter content, and relative growth rate), and calculated species and functional richness. Increasing S. mexicanum cover reduced spontaneous species abundance and species and functional richness but did not affect community biomass. Species richness was affected by the interaction of S. mexicanum cover and watering treatment and was greatest in well-watered microcosms with 0% S. mexicanum cover. Increased water availability increased spontaneous plant biomass but did not affect functional richness. The SLA of spontaneous communities was affected by the interaction of S. mexicanum cover and watering and was significantly greater in well-watered treatments where S. mexicanum cover was
... The use of soil as a sole substrate in green roofs is not highly recommended due to several disadvantages (the clogging of the filter layer, spreading of weed seeds and the high cost of controlling, loss of porous structure due to soil compaction, etc.) (Calheiros & Stefanakis, 2021). Nonetheless, lightweight textured soil can be preferred, as well as soil combining high organic matter content (farmyard manure, compost, peat, decomposed sawdust or bark, cocopeat, etc.) and inorganic materials (perlite, volcanic tuff, pumice, rockwool, schist, vermiculite, etc.) in certain proportions (Aslanboğa, 1988;Ürgenç, 1990;Johnston & Newton, 1993;Ampim et al., 2010). In recent years, mushroom compost and sewage sludge have been included in these materials. ...
This research was carried out in Izmir-Turkiye and investigated the potential of using three different substrates (cocopeat, loofah and perlite) in the design of green roofs with succulents (Crassula ovata) in aim to improve their performance. In this research, four different groups (G1: Soil-Cocopeat, G2: Soil-Loofah, G3: Soil-Perlite and G4: Soil) were created according to the plant growing media used in the planting layer. The researchers conducted measurements of the drained irrigation water’s EC (Electrical Conductivity) value, pH value and drainage amount, the plant growing media’s temperature and moisture, the plant’s height and leaf number, and the amount of subsidence in the planting layer. In line with the results obtained from the evaluations of the analyses, it is possible to say that perlite (G3) offers more advantages than its alternatives in terms of many variables. However, according to the conclusive results, it has been understood that the use of a single type of substrate as plant growing media would not be sufficient to encourage the maximum performance of green roofs. To ensure that, considering the advantages of each substrate group, it is proposed that their combined use would be more beneficial.
There is a growing need of sustainable building development all over the world. It aims to decrease the adverse effects to the environment due to urbanization and escalating population growth. Since the building construction is considered as one of the main concerns, the priority was given to mitigate the negative impact to the environment. Therefore, incorporating sustainable elements and techniques to the buildings to regain the land loss due to construction activities in cities is currently practicing. Adding various vegetation types through different approaches, to obtain the expected results of better living condition around the building is called as building integrated vegetation systems (BIV). Vertical gardening systems, vertical farms, constructed green roofs and roof farms can be stated as main categories of BIV systems. However, there is a paucity of published critical reviews on such systems and therefore, this study is an attempt to review the overall sustainability aspects of BIV systems including environmental sustainability, economic sustainability and social sustainability. This study consists with a critical review of 114 research publications from relevant journals and online scientific databases. Finally, the identified sustainability aspects of each BIV systems were analyzed to select the best option in terms of greening a building which can be recommended for the implementations in future. Mainly, the importance of moving towards the sustainable solution which meets the food needs through BIV is finally discussed. Finally, it can be concluded that by incorporating green architecture with smart agriculture, we can expect green, healthy and productive cities which fulfill the main requirements of sustainable cities. Though there are many challenges to overcome, maintaining good management practices will give better output. Out of the 114 literature selected for this study, only 8 research papers were discussed about the drawbacks and the limitations of the BIV systems which is still having paucity of information. Keywords: Building Integrated Vegetation systems, Economic Sustainability, Environmental Sustainability, Social Sustainability
Probiotics can increase feed conversion efficiency and strengthen the immune system of
aquatic animals, resulting in improved growth and survival rates. Common probiotics used in
aquaculture include lactic acid bacteria, Bacillus species, and yeast.Aquaculture can continue
to grow by using probiotics in fish breeding and rearing technology, minimizing their
exposure to diseases.This study aims to compare the effectiveness of different bioactive
substances, such as probiotics, prebiotics, and mannan oligosaccharides, in stimulating the
growth and survival of juvenile carp
The runoff from and the water balance of a thin extensive green roof with sedum-moss have been studied. The soil cover is about 3 cm underlain by a thin drainage layer. The water balance is determined on a monthly basis. The runoff from the green roof is much reduced compared to runoff from hard roofs because of evapotranspiration. The annual runoff is rather close to that of natural river basins. Although most rainy days there is no or little runoff from the roof, the highest observed daily runoff values are close to the daily rainfall. Runoff is initiated when the soil is at field capacity, which for the studied roof corresponds to 9 mm storage. After that, on a not very short time basis, the runoff equals the precipitation. The reduction of the daily runoff can be described in a simple way knowing the daily precipitation, potential evaporation and storage capacity of the green roof.
Soilless container media have almost no capacity to retain PO4 or K. The nutrient retention of two calcined clays, attapulgite and arcillite, and brick chips, precharged with PO4 and K, was investigated. These could serve as an alternative slow-release fertilizer when incorporated into a soilless medium as a component of the mix. Sorption curves were developed at 25 °C for attapulgite of two particle sizes (0.8 to 1.6 mm and 1.6 to 3.2 mm), arcillite (1.1 to 3.2 mm), screened pieces of brick (1.0 to 3.6 mm), and a medium of 7 sphagnum peat : 3 perlite (v/v) using solutions of KH2PO4 (P at 0 to 20,000 mg·L-1). Curves indicated that PO4 and K sorption were similar for both particle sizes of attapulgite, so only the larger size [1.6 to 3.2 mm (8 to 16 mesh)] was used in greenhouse studies. Materials were evaluated in greenhouse studies by growing 'Sunny Mandalay' chrysanthemum [Dendranthema xgrandiflora Kitam. (syn. Chrysanthemum xmorifolium Ramat.)]. The precharged materials were tested at 10%, 20%, and 30% by volume of a peat : perlite root medium. Phosphate, K, and pH were determined on unaltered medium solutions collected throughout the cropping cycle and foliar analyses were determined on tissue collected at midcrop and end of the crop. Data indicated that precharged calcined clays retained and released PO4, and to some degree K, over time. Precharged clays did not provide K at levels which met plant needs during the latter half of the cropping cycle, but it was released and used at appreciable levels during the first month of crop production. Growth of plants receiving PO4 solely from precharged attapulgite and arcillite at 20% of the medium volume was not significantly different from that of a commercial control when the leaching fraction was maintained at 0.2. However, release of PO4 from the brick chips was not enough to match plant demand. Phosphate lost through leaching from the precharged clays was reduced by about two-thirds compared to control plants fertilized with P at 46.5 mg·L-1 from water-soluble fertilizer at each watering.
On the roof of a building 90 shallow containers were filled with 10 cm substrate. This first year was characterized by annual plants. The living conditions on the north side (60 species, which produced 48.4 g/m² biomass May-September) are better than on the south side (38 species 18.3 g/m² biomass). -from Author
Use of green roof technology is becoming increasingly widespread throughout the world because of its environmental, economic, and aesthetic benefits. The ability of a green roof to retain stormwater and limit the amount of fertilizer in the effluent flow are important characteristics of a properly installed green roof system. However, scientific research quantifying these characteristics is limited - particularly in the United States. Simulated rooftop platforms were constructed and runoff was analyzed from four commercially available green roof systems containing three distinct vegetation types. Quantity of rainfall retained ranged from 38.6% for Xeroflor to 58.1% for Siplast. Quantitatively, Xeroflor resulted in the greatest volume of runoff, but these volumes were only significant for the sections of Sedum plugs and seed during the fourth rainfall event. Differences in water retention can likely be attributed to substrate depth, rather than drainage system or vegetation type. Results demonstrate two important concepts that affect the amount of stormwater a green roof can retain - substrate thickness and substrate moisture content immediately prior to a rainfall event. Nitrate concentrations in the runoff varied from 0.22 ppm in the Sarnafil native plant sections 314 days following fertilizer application to 22.7 ppm in Xeroflor Sedum seed sections 314 days following fertilizer application. No significant differences were observed between any of the treatments with regard to phosphorus concentrations.
Because of greater interest in green roofs in the United States, it is critical to increase the number and geographic range of proven plant resources for long-term survival on rooftops. Successful plant taxa for extensive green roofs must establish themselves quickly, provide high groundcover density, and tolerate extreme environmental conditions. Furthermore, dead load weight restrictions on many buildings may limit the substrate depth that can be applied. The objective of this study was to evaluate the effect of substrate depth on initial establishment and survival of 25 succulent plant taxa for green roof applications in the midwestern United States. Survival, initial growth, and rate of coverage were compared for plants grown in three substrate depths (2.5, 5.0, and 7.5 cm) on 24 roof platforms. Plant coverage was determined from image analysis of weekly digital photographs. Results indicate deeper substrates promote greater survival and growth; however, in the shallowest depth of 2.5 cm, several species continued to persist. Of the 25 species initially planted, only 47% survived in the deepest substrate of 7.5 cm. Recommended species at the depths tested for climates similar to southern Michigan include Phedimus spurious Raf. 'Leningrad White', Sedum acre L., S. album L. 'Bella d'Inverno', S. middendorffianum L., S. reflexum L., S. sediforme J., and S. spurium Bieb. 'Summer Glory'. Subsidiary species that are present at specific substrate depths but may not exhibit an ability to cover large areas include S. dasyphyllum L. 'Burnatii', S. dasyphyllum L. 'Lilac Mound', S. diffusum W., S. hispanicum L., and S. kamtschaticum Fisch. The primary deterrent for these subsidiary species was little to no survival at 2.5 cm. Deeper substrates promoted greater survival and growth for nearly all species tested.
Four substrates were investigated for their efficacy as roof garden vegetative layers. The substrates comprised a sandy loam soil (S), sandy loam soil amended with urea formaldehyde resin foam (S:F) in a proportion of 60-40 v/v, sandy loam soil amended with peat and perlite (S:P:Per) in a proportion of 50-30-20 v/v and peat amended with urea formaldehyde resin foam (P:F) in a proportion of 60-40 v/v. The substrates were evaluated for their physical and chemical properties and their capacity to sustain growth of Lantana camara L. Physical and chemical evaluation included weight determination at saturation and at field capacity, bulk density determination, water retention, air filled porosity at 40 cm, pH and EC. When compared to the control (S) a weight reduction of 16.8%, 23.9% and 70.3% was obtained at field capacity with S:F, S:P:Per and P:F substrates respectively. Bulk density was reduced by 46%, 43% and 95%, in substrates S:F, S:P:Per and P:F, respectively, compared to the control substrate S. Air-filled porosity at 40 cm was slightly increased for substrate S:F while it was substantially increased for substrate P:F. The pH response between the initiation and the termination of the study was similar for the four substrates. EC decreased in substrates S and S:P:Per but increased in substrates S:F and P:F. Plant growth was monitored as shoot length, shoot number, main shoot diameter and the number of buds and flowers. Substrates S and S:F resulted in similar plant growth, while substrate S:F promoted flowering. Substrate S:P:Per induced slow plant growth during the first 6 months which subsequently increased resulting in a final growth that was satisfactory and comparable to the S and S:F substrates. Substrate P:F did not support sufficient plant growth and its use should be considered only in special cases where reduced weight of the roof garden is imperative.
Green roof technology in the United States is in the early development stage and several issues must be addressed before green roofs become more wide-spread in the U.S. Among these issues is the need to define growing substrates that are lightweight, permanent, and can sustain plant health without leaching nutrients that may harm the environment. High levels of substrate organic matter are not recommended because the organic matter will decompose, resulting in substrate shrinkage, and can leach nutrients such as nitrogen (N) and phosphorus (P) in the runoff. The same runoff problems can occur when fertilizer is applied. Also, in the midwestern U.S., there is a great deal of interest in utilizing native species and recreating natural prairies on rooftops. Since most of these native species are not succulents, it is not known if they can survive on shallow, extensive green roofs without irrigation. Five planting substrate compositions containing 60%, 70%, 80%, 90%, and 100% of heat-expanded slate (PermaTill) were used to evaluate the establishment, growth, and survival of two stonecrops (Sedum spp.) and six nonsucculent natives to the midwestern U.S. prairie over a period of 3 years. A second study evaluated these same plant types that were supplied with four levels of controlled-release fertilizer. Both studies were conducted at ground level in interlocking modular units (36 × 36 inches) designed for green roof applications containing 10 cm of substrate. Higher levels of heat-expanded slate in the substrate generally resulted hi slightly less growth and lower visual ratings across all species. By May 2004, all plants of smooth aster (Aster laevis), horsemint (Monarda punctata), black-eyed susan (Rudbeckiet hirta), and showy goldenrod (Solidago speciosa) were dead. To a lesser degree, half of the lanceleaf coreopsis (Coreopsis lanteolata) survived in 60% and 70% heat-expanded slate, but only a third of the plants survived in 80%, 90%, or 100%. Regardless of substrate composition, both 'Difrusum' stonecrop (S. middendorffianum) and 'Royal Pink' stonecrop (S. spurium) achieved 100% coverage by June 2002 and maintained this coverage into 2004. In the fertility study, plants that received low fertilizer rates generally produced the least amount of growth. However, water availability was a key factor. A greater number of smooth aster, junegrass (Koeleria macrantha), and showy goldenrod plants survived when they were not fertilized. Presumably, these plants could survive drought conditions for a longer period of time since they had less biomass to maintain. However, by the end of three growing seasons, all three nonsucculent natives also were dead. Overall results suggest that a moderately high level of heat-expanded slate (about 80%) and a relatively low level of controlled-release fertilizer (50 g·m-2 per year) can be utilized for green roof applications when growing succulents such as stonecrop. However, the nonsucculents used in this study require deeper substrates, additional organic matter, or supplemental irrigation. By reducing the amount of organic matter in the substrate and by applying the minimal amount of fertilizer to maintain plant health, potential contaminated discharge of N, P, and other nutrients from green roofs is likely to be reduced considerably while still maintaining plant health.