Successful landscaping and gardening on balconies and rooftops, especially of condo towers, has many challenges that residents with terrestrial gardens in homes don’t share.
My goal with this forum is to make the reader/contributor aware of these somewhat complex issues, offer simple, straightforward solutions when I have them, share resources, and garner constructive input from other interested parties so I can continue to help sky gardeners meet these challenges. Hopefully, gardeners can make high-density urban environments not only more beautiful, but also more eco-friendly with low-lifecycle-cost, sustainable Gardens in the Sky.
Residential and office condo towers are increasingly prevalent in dense urban and coastal areas, and contribute to the formation of “heat Islands” and global warming by adding heat-retaining surface area, unless they can be landscaped. In addition, according to the American Institute of Architects (AIA) , buildings are the leading source of greenhouse gas emissions in the United States. According to estimates in the AIA’s Architects and Climate Change report, buildings represent 48 percent of carbon dioxide emissions, with transportation and industry representing 27 percent and 25 percent respectively.
The Green Roof movement is great, but the ratio of wall-to-roof area is much greater on high-rise buildings.If Architects designed balconies with drainage and water spigots built into their clients’ high-rise buildings, it would make it easier for residents and offices to help offset their impact to a far greater degree, both in terms of cooling and exchanging oxygen for carbon, and absorbing other pollutants.
When I was developing a condo building in Miami, where my wife and I now live after years at sea, I wanted to create a livable rooftop with lush landscaping. Frustratingly, we were unable to convince the city building department, in 2004, that green roofs were insulation in and of themselves, so we were unable to have a grass roof. I realized, however, that the roof surface area of a condo tower was a much lower percentage of the building surface area than the walls themselves. Therefore I began a search for large lightweight planters that had a high ratio of surface area to weight to use both on the roof and balconies.
At the same time, I wanted to avoid problems associated with built-in concrete planters located on the roof, such as leaking and creating expensive structural damage to the building.In addition to being immovable, there are limitations on where built-in planters can be located, they are impractical on cantilevered balconies, and they impart heaviness to the building design that I wanted to avoid.
While lots of great looking pots exist, large surface area planters were scarce. Also, as I was soon to learn, pots had serious drawbacks for use up on buildings, especially on sunny south and west facing exposures. As I proceeded through the sourcing process, I eventually assembled a list of attributes that I felt was important in these planters:
·Large surface area
·Variety of dimensions and materials
·Durable, with a low lifecycle cost
·Low impact on the environment
·Thermal protection for roots
·Stability in high winds
·Easy to water
Ultimately, I could not find what I was looking for, so I started my own design and manufacturing company to create customizable planters to address all these issues.
DeepStream Design HD website
I have found solutions to my issues and, in the process, discovered valuable resources for planters, irrigation systems, and drainage control, as well as some dead ends that I will share.I hope that my readers will contribute their own innovative ideas and experiences in creating a green roof, roof garden, and landscaping a balcony or patio so that we can green up these new high-density vertical neighborhoods sprouting up all over, and minimize our environmental impact.
Be forewarned: I don’t have a green thumb and I almost named my blog “The Reluctant Gardener!” I’m certain that readers/contributors to this forum can add a great deal of sage advice from their own experience when it comes to what works in terms of plants, soils, irrigation, and containers when creating a green roof, balcony, or patio. I must admit, though, that I have one of the most vibrant rooftops in our neighborhood, even if I wasn’t able to plant grass, and I have killed a plant or two in the process.
All in all, it’s been fun. I find the “Zen” of sitting among my plants with friends at sunset or for morning coffee before a long bicycle ride very rewarding. Even if my siblings find the thought of me gardening to be extremely amusing, I still enjoy eating the tomatoes and mangoes I’ve grown in the sky.
Using the services of a Landscape Architect is highly recommended to shortcut the process of creating a pleasing space integrated with your lifestyle and goals.Keep in mind that, as in any profession, many practitioners have found what they consider to be tried and true practices and may not have kept up with changes in the industry, so you need to be informed.A true professional will welcome your respectful input because the ultimate goal should be your satisfaction.Don’t be intimidated; share your ideas and feedback with them.
You may be unfamiliar with many of the resources I list, as they are sources used by Landscape Architects; however, the quality of products found using these resources are of a professional grade, and thus the impact on the environment, and the lifetime cost of these products is far lower than many “consumer” products that literally define planned obsolescence and a harmful throw-away society.
Challenges and Solutions:
Foremost among the problems I faced in sourcing large planters with substantial surface area was finding any large planters at all, let alone contemporary planters in a variety of styles and sizes that provided protection from soil overheating on south- and west-facing exposures, water drainage control,stability in high winds, ease of watering, and portability.
Large surface area: Large planters, especially attractive ones, were surprisingly hard to find.While there are lots and lots of pots of various sizes, they really do not provide the large surface area to plant trees, hedges or vines necessary for the shade and privacy screening that I wanted for larger areas and rectilinear balconies.
Aesthetic: Planters that I found with large surface areas looked more institutional or commercial in design and were more appropriate for a parking lot.They simply did not possess the appropriate design attributes of architectural planters for a residential project.
Variety of dimensions and materials: Again, none of the ready-made large planters that I was able to find were available in custom sizes to fit all the niches and variety of areas that I needed planters for.While there may have been a choice of color, there really was not a choice of materials that would impart varying but compatible looks as one finds in pots.In Landscape Architect terms, these large planters fall under the “site amenities” category and are really more appropriate for streets, parks and parking lots.
Each type of material used in construction has its advantages and disadvantages, which vary greatly with construction and design:
Ceramic and cement are not waterproof, and cement planters have steel re-bar at their core. Steel, which expands to 20 times its size as it rusts, cracks the cement, leading to complete failure.If a concrete planter is appropriate for your project, ask the manufacturer to add Xypex® to the mix before construction to retard this process for as long as possible. add Xypex® to the mix before construction to retard this process for as long as possible.
Cement planters are very heavy to take up elevators and stairwells, and they are just as much work to remove.You may need a crane. There are some lightweight concrete planters coming onto the market now that may do a better job if they can be adequately waterproofed.
Issues with Cement Planters
The ratio of surface area to weight, and lack of controlled drainage limits large cement planters to the ground. Light color cement planters of great mass offer some protection from solar gain, although they hold heat well into the night.
Concrete planters with rebar will develop cracks along the reinforcing grid
Un-reinforced cement planters break easily.
Planters have no means of drainage control leaving a mess.
Issues with Ceramic Planters
Large ceramic planters have some of the same drawbacks as cement, although thinner walls make them lighter and more fragile, at least they do not have steel at the core. While they provide some protection from solar gain through evaporative cooling when wet, more than a couple of hours of sun will dry them out. There are no large surface area ceramic planters that I am aware of.
Ceramic planters should not be painted as they will peel immediately.
Initially I was drawn to the wood planters you see at street cafés all over Europe, but every planter I saw was falling apart.With my experience in yacht maintenance and rebuilding, I could see that existing wood planter designs were not built to last for decades.
Available wood planter construction techniques fastened wood to wood, and planters would tear themselves apart with the expansive forces that wood exerts through repeated wet and dry cycles.
For centuries, wood dowels have been inserted into holes drilled into rock, then soaked with water.The expansion force of the wood is thus harnessed to crack blocks off marble and granite for construction, even though the blocks are hundreds of times thicker than the thin wooden dowel.
Since every wooden plank is cut from a different part of the tree, it has its own differential rate of expansion and warping when wetted. This makes dimensional stability using standard wood-on-wood construction in two dimensions impossible to maintain over time, and shipbuilding techniques are far too costly for planter construction. In addition, most wood planters lack adequate isolation from the soil and the deck or sidewalk, which promotes fresh water rot.
Issues with Wood Planters
New wood planters constructed by traditional methods.
Traditional construction warping after just a few months, wood feet on deck.
Horizontal to vertical separation pulling fasteners out, panels separating.
Vertical grain splits, warps, & rots
Vertically exposed end grain, and non-tropical hardwood quickly succumbs to rot and splitting, even using heavier bolted construction
Unsupported and exposed liners are problematic and unsightly.
While wood will go grey over time just like your teak garden furniture, unless you spend time varnishing them often, tropical hardwoods have been used for centuries for shipbuilding, boardwalks, docks, etc.If you like the character that time imparts to wood, as I do, a planter constructed using my techniques can last for decades.
DeepStream Designs horizontal planked tropical hardwood planters are constructed without frames, properly isolated from wet decks and soil with properly supported, watered and drained liners. They can look good for decades.
Plastic and resin can be excellent materials if the materials incorporate UV stabilizers.High-quality resins should be able to last for at least 10 years, but even then the surface will get chalky over time. Fiberglass can be waterproof if the proper marine resins are used or a barrier coat has been applied, but like resins and plastic it will develop a chalky surface over time. Proper marine resins and barrier coats are very expensive, if a Fiberglass pot is cheap is will not last but just because one is expensive does not mean it is well made. Personally, I really like the ones that incorporate materials such as copper in the epoxy resin so that the patina improves over time.
Issues with Plastic, Fiberglass, and Foam Pots
The major problem with all these pots in a sunny location is lack of protection solar gain, even more than than size, shape, and longevity.
While there are many cheap plastic pots from home stores, I have never seen one large enough to be called a planter, and I can’t resist a word of caution. All of those cheap pots are too thin, contain no UV filters, and they quickly get brittle and break down.Many have painted exteriors that will soon fade and peel. One particular series of plastic pot found at a national home store chain actually has a two-part construction that can fool you into thinking that they are of higher quality than they actually are. After a couple of months, they separate and the thick top rim falls off.Others are constructed of cheap foam covered with other materials, which quickly break down, and fall apart.
Home store chain pots a year old, note the roots growing through the drain holes splitting them apart.
While ok if shaded, another shortcoming of plastic pots, aside from a short life, is that available pots are too small for larger plants and the taproot grows out of the hole on the bottom, ripping the pot and making it unstable. Note the surface degradation of the foam core plastic pot, even in the shade.
Just getting some of the plastic and foam core pots from the large home store back home without breaking proved impossible.Their design and construction was totally inadequate, sacrificed in the quest for the lowest initial cost to lure in suckers like me!When I calculate the time and effort expended to select, buy, return, buy, return for credit, and then start the process over again, the cost of that lesson was very high indeed.And that is without all the hassle and mess of planting and unplanting. So much for value at the low end of the spectrum.
More examples: relatively expensive foam core pots, above, show typical surface degradation in just a few weeks.
Contrary to popular belief most fiberglass construction is very prone to breakage
While most fiberglass planters are light, at the expense of strength, they may not be durable enough for certain location. In addition they are almost all single-walled and prone to solar gain. White or light-colored ones would be better in sunny locations. They do not have drainage control, nor do they hide drip irrigation lines. The expensive large ones above are installed in Miami’s downtown area and while shaded by buildings, they are not really rugged enough for the streetscapes in which they are installed, nor do they have much surface area. Believe it or not, these planters are just 1/8″ thick painted skins of chopped fiberglass sprayed into a mold.
Metal planters have various issues depending on the metal and the design. There are very few large surface area metal planters, and most are forms inappropriate for windy locations. All metal passes solar gain rapidly and is not appropriate on long sunny south and west exposures unless there is a separate liner inside. Steel, iron and all forms of ferrous metal rust, including stainless steel. Cast aluminum and bronze can have great longevity depending on the alloy. Zinc and copper patina nicely, but the seams will soon leak if there is no liner. Again, there are very few large surface area metal planters, as the metal is thin and non-structural.
Issues with Metal “Planters”
Metal planters leaking with rusty seams and rust through pin holes
Thermal Protection: From the plants’ point of view, thermal gain is as deadly as over- or under-watering. Pots and most existing planters also lack insulation qualities to protect the soil from solar gain. On a sunny 80º day, the sun can heat a dark single-layer pot to a surface temperature of 120º, and on a 90º day, the surface temperature can measure 140º or more, with the soil measuring 110º+ on the sunny side of the pot.
Within minutes of moving a fiberglass pot into the sun the surface temperature climbed to 125 degrees on a 84 degree day, while the “liner within a planter” concept in the wood planter behind it keeps the soil no warmer than the temperature of the air.
No matter how much water we gave plants with hot soil, they didn’t do well. Pulling a plant out of a dark pot I found that the roots were literally being steamed! Unless there is a thermal break between the wall of a planter and the container for the plant, the solar gain is transferred to heat the soil. A proper thermal break will keep the soil no warmer than ambient air temperature and prevent both thermal shock and steaming the root system.
These newly planted palms already show signs of stress in limited morning sun. The edges of the leaves turn brown and over- watering rots the heart out of the palm closest to the sunny side so it is lost. Sea Grapes are much heartier, but will eventually succumb.
Only true low solar gain Low-E glazing, which is expensive, can block solar gain. Tinted glass is not enough on south- and west-facing exposures.
Even the browning palm (above top) in the ceramic pot, which has some measure of evaporative cooling when wet, suffers heat stress. The Robellini palm (above bottom) had no chance of survival. It has lost the two east facing trunks even though the fiberglass pot is in the afternoon shade of the parapet wall.
If you are using a single wall planter in an exposed sunny location and not getting good results then try to place it behind a barrier to solar gain as you see in this picture.
Here you are looking south west so the building shades the planters in the morning, then full sun for about 2 hours and then the low parapet shades the planters all afternoon.
Drainage control is important for several reasons:
·If planters do not drain properly, plants drown or develop root rot.
·If drainage is too easy, then water is wasted, which can be problematic when faced with water and/or time restrictions and nutrient wash out.
·Very few condo, converted loft or apartment buildings have drainage built into the balconies for planters or pots.Having dirty water overflow from balconies and run down the side of the building or drop onto unsuspecting pedestrians and autos is usually not an option, and may be a violation of your condo rules as well as local city codes.
Condo Boards and building management are understandably reluctant to let residents have more than a pot or two outside on a balcony that can be brought in when it rains.While rooftops generally have drainage, it’s not usually where you need it, so they too have issues when creating a landscaped or green roof, even on a limited scale.
Drainage that is limited to a hole on the bottom, even covered with drain board and filter geotextiles, is especially prone to quickly repeated blockage that requires a lot of effort to restore.
Ease of watering: this challenge is more complicated than it initially appears:
·First there is the issue of meeting watering schedules imposed by many municipalities, which may include watering at night.
·Watering large planted areas, or a great number of planters, with a hose is very expensive in terms of time.
·Many large planters can be landscaped with plants that have varying root depths.
·Planters that have a reservoir system only water to one depth, so planting flowers or bushes to surround trees is impossible without additional water sources. Even then the deeper-rooted plants can be over-watered and drown without great care in watering and plant selection.
·There is also the challenge of providing automatic watering systems without interfering with the aesthetics of the overall project. None of the planters designs shown above have a way to hide drip irrigation lines.
Low lifecycle costs, low impact on the environment: These two issues really go hand in hand.
Most developers want to create a “look” without costing a lot of money because the object is to sell the residences for the most money while spending the least amount of money delivering that look so that profit is maximized. Resident owners may be limited by their budget but are, in general, looking for the lowest possible cost over time.
Quality almost always delivers the lowest cost over time. A well-made product that costs twice as much, but last three times as long costs less money over time and exacts less of a cost on the environment.It also takes far less effort on the purchaser’s part, reducing acquisition and delivery costs, as well freeing up resources for other uses.
Often the cost of the product is confused with quality. The quality-cost equation comprises not only materials and construction, but also thoughtful design, careful purchasing, manufacturing, distribution, and sales cost. While two planters of equal aesthetic appeal and surface may cost the same amount, to truly evaluate value you need to compare the longevity of the design and material.
The lifecycle cost of a product greatly affects its environmental cost. Every material used in construction exacts a toll on the environment. I’ll not argue the relative merits of plastic over fiberglass, or cement over wood, or aluminum over steel. Figuring out the true costs of the energy used by each process, the damage to the earth, and the recyclability of each material is beyond the scope of this forum.
In general terms, products will have a lower impact on the environment if:
·They are aesthetically pleasing, but not trendy, so that you can enjoy them for a long period of time;
·They have a modular design, constructed with replaceable parts so that they can be easily repaired instead of discarded should they suffer a mishap;
·High-quality, long-lasting materials appropriate for the intended environmental conditions are used in construction;
·They are made from distinct materials that can each be easily separated and recycled;
·They use materials from renewable resources;
·The company you purchase them from invests more back into conservation than it takes from the environment.
Light weight: Most of the large surface area planters I found were made of cement, which may be too heavy for balconies, and even for roof loading, at the expense of soil depth required for the plants.
Stability in high winds: While the weight of cement has an advantage here, proper design can greatly increase stability. Many planters and pots are not appropriate for outdoor use because the bases are smaller than the top and the surface of the soil may be so high that they are top heavy. If they are blown over, many may break or worse. In many locations, wind can routinely be in excess of 20 mph and may well exceed 70 in gusts. You need to consider: If my planter is blown over will it blow off my roof or balcony?
The Issue of Form to Stability
Even light gusts tip pots
All in all, finding lightweight, attractive, large volume planters with drainage control that provide a thermal break with an appropriate design aesthetic in a variety of sizes proved to be impossible, let alone planters that would also stand up to the test of time and the rigors of the property maintenance team.
I started landscaping my building in 2004 with the SeaCrest series of large planters from Tournesol Siteworks as a good plastic planter solution. Every planter available at the time had some compromise, so despite the institutional look imparted by the roto-molded plastic construction, they answered most of the other challenges.
I ordered and installed more than a dozen of the 48” round and 72” rectangular planters for the rooftop, where we were able to engineer in the load capacity to hold their fully wetted weight of at least 2,300 lbs for the cylindrical planter and 1,500 lbs for the rectangular planter. We planted the round planters with 6’ high 3-stem Robellini palms.We planted two Jatropha bushes in the rectangular planters.
I highly recommend this company and their planters if the look of their products is appropriate for your venue.They make many of the liners we use in our planters, especially when we need custom sizes and forms to fit custom projects for customers.
While the SeaCrest planters are designed with self-watering reservoirs, we found that it was better to put them on drip irrigation (more about that later), but the double wall design for the reservoir planter provided just the thermal break that has allowed our plants to thrive despite the baking Miami sun.
The drainage is a bit iffy, but if you take the extra steps I outline below you should have good results. One other issue with the long 72” rectangular planter that arose is that the middle of the planter tends to bulge from the heat of the sun combined with the pressure from the soil, which creates a “creep” in the plastic.I understand that Planter Technology may have added a baffle in the middle to prevent this. I think that “creep” could be a problem for almost any single wall planter made from non rigid material like plastic, resin, and even fiberglass as the thickness required without a “web” for large planters is cost prohibitive.
A New Concept:
Since I found that there were really no planters on the market for the balconies and rooftop deck on my project that fit the demanding criteria for large modular planters, I created DeepStream Designs to create commercial planters of a Landscape Architect grade that would meet the complex design criteria I listed above.
I’m not going to recreate the commercial DeepStream Designs.com website here, but since a picture is worth a thousand words so you may want to give www.deepstreamdesign.com the new HD site, a quick look over so that the information below has some context. You may notice that at this point I have only designed rectilinear forms.
Ultimately, to create planters with the large surface area and aesthetics that I was looking for, along with an unlimited variety of dimensions and materials, I had to create two different planter systems: The Mariner Planter for the special challenges of wood and the Audubon Planter that allows planters to be constructed using any other material suitable for outdoor use. Both designs rely on the science and engineering of DeepStream’s “Liner within a Planter” concept for the ultimate health of the plantings, while providing the lowest lifecycle cost for the planters.
Mariner planters were designed exclusively to overcome the challenges of constructing wood planters that will last decades while showcasing my favorite material. This is a frameless modular system that allows the wood to expand and contract within the slot of a heavyweight marine anodized aluminum leg without destroying the structural integrity of the planter box. Since the planking is free to expand, but held at the ends by the legs, the planks are essentially the frame.
Audubon Planters use DeepStream’s unique modular Anti-Gravity©frame system that allows planters, or façade systems of any size, to be made from panels of any suitable material.
3Form Bear Grass UV filtered resin
DeepStream’s unique frame system allows the use of any appropriate material
Any stone can be used, here is green marble. Raised feet allow for easy cleaning on balconies
Copper or any appropriate metal
Shared Design Features
In theory, only the length of available wood planks for Mariner planters and panel material for the Audubon planters would limit planter size; however, with intermediary legs, the size of either system can be expanded to infinity.
In practicality, the size of a single Mariner or Audubon planter box is limited to 72” in any one horizontal dimension. Dimensions over 72” require that a planter box become a facade that hides a planter liner, or a series of liners, which rest their weight on the building instead of being suspended by the planter box legs. Practical considerations include not only available wood plank lengths, or material sheet size and stiffness for the Audubon planter, but also available planter liner sizes and the combined weight of the soil and plantings.
Planter liners are constructed from High-Impact Polystyrene and Low Density Polyethylene (LDPE). The separate planter liner is a critical design component, providing a thermal break between the planter box, which absorbs solar gain, and the roots, thus ensuring that the soil is never warmer than the ambient air temperature.This design feature is crucial for plant health on rooftops and southern exposures and cannot be overemphasized.
The liner hangs from a frame attached to the legs, this keeps the edge of the planter hidden, allows air to circulate, and no leaves or dirty water collects. Drip irrigation lines can be attached to the frame keeping it out of sight and run up to the planter hidden between the liner and the exterior planter box.
The separate waterproof liner also is the key to preventing contact between wet soil, wood, and metal. This design feature ensures greater durability of all materials, thus providing the longest product life, the lowest possible lifecycle cost, and the lowest impact on the environment.
DeepStream’s two-part “Liner within a Planter” design is also a key component in drainage control while making watering easy, efficient, and attractive.Every liner can be fitted with an optional drainage system that uses a fitting placed through the liner wall about an inch-and-a-half above the bottom, a filter, a valve, and a hose that can be hooked up to a variety of drainage systems.
The drain, fitted to the wall of the planter liner, is more protected from blockage common for bottom-mounted drains.It also provides space for water to accumulate in dry periods to reduce water use and promote plant health. It is a water storage space that can be increased by closing the valve during dry seasons or periods of watering restrictions. The valve allows the drain to be opened during heavy rains to prevent dirty water overflowing from the top of the planter.During heavy rains, the rain will wash away filtered water even without a drainage system hooked into the building’s storm drain system.
Reservoir planters may be mandated by existing building design in some public areas due to complexities of providing a water source. However drip irrigation, with a timer and rain sensor, along with DeepStream’s drainage control system, which eliminates drowning the deeper-rooted plants, has proven to be the best way to water plants on our building.
Drip irrigation provides a natural top-down watering of the soil using a combination of drip emitters, spray heads, and misters that are best for simple and complex plantings with roots systems at different soil depths. Drip irrigation systems can be run off a low pressure “rain barrel” or the building’s high-pressure water system. Unlike single wall planters or pots, DeepStream’s two-part “Liner within a Planter” design hides drip irrigation lines that must run visibly up the outside of single wall planters or pots.
Durability, modular design with replaceable parts, low lifecycle costs, and minimizing impact on the environment all go hand in hand. To ensure that planters are durable enough to last for decades DeepStream manufactures its wood planters using recyclable marine-grade anodized aluminum and stainless steel fasteners assembled with a special dielectric paste to prevent electrolysis between the dissimilar metals. Aluminum is the world most abundant mineral and it also uses the least amount of energy to be recycled.
The feet on DeepStream’s planters keep the wood from the wet deck, preventing rot induced by wood resting in standing water. They are made from HDPE, a recyclable marine plastic that will not scratch decks and will not absorb water. Our planter liners, constructed from High-Impact Polystyrene and Low Density Polyethylene, are recycled and recyclable.
Tropical hardwoods have been used for centuries in shipbuilding, dock, boardwalks, railroad ties and other extreme outdoor uses because their oil content makes them insect- and rot-resistant.Even so, these tropical hardwoods are not rot-proof and they can warp, twist, check and split, which to my mind adds character that is missing in today’s mass products. Our system will minimize all these aspects and contains the wood planks in a structural package for decades. If a plank should need replacing, the modular design means any plank or part of the planter can be replaced.
All of our wood is purchased here in the US so that it meets all environmental import source standards. Additionally, for every planter DeepStream sells, regardless of the construction materials, we plants 50 trees in Brazil.This is done in the name of the customer through a donation to Trees for the Future, http://trees.org/
Recycled Plastic Lumber (RPL) In keeping with our mantra “Reduce, Reuse, Recycle,” DeepStream has been offering Commercial Planters & Recyclers built with HDPE planks made from recycled milk jugs. We stock 5 colors of this Green material and it is growing into a major part of our business due to it s low maintenance and the 50 year warranty by its manufacturer. Unlike wood RPL is non-structural and DeepStream has pioneered special construction methods to ensure that structural integrity of large planters is maintained.
Almost any other materials can be used in the Audubon system and each has its own characteristics, longevity curves and environmental impact.For instance, there are fantastic looks in new UV-resistant resins from 3Form and Reynolds Polymer, just to name a few, that use natural material in the design and can be recycled. The primary laminate backing material for translucent resins is recycled and recyclable expanded PVC.
Tried and true marble or stone of any type, which can last for centuries, is given a new twist when we laminate it to ultra-stiff lightweight honeycomb aircraft aluminum panels so that a 42” planter box is lighter than wood, weighing in at about 52 pounds instead of hundreds of pounds. This allows marble planters, even with 18” of soil, to be used on a balcony or roof project. Even our largest 72” Mariner wood planter weighs only 112 pounds with a 16-pound liner. All of our planters can be shipped assembled and still go up an elevator or stairway easily, or they can be shipped flat and assembled in about 20 minutes with a Phillips head screwdriver.
Stability in high winds is a function of form, height and leverage.In high-wind situations, a square planter has better stability than a rectangular one, and a low planter has better stability than a high one. Of course, a low bush is going to impart less leverage than a tall thick clump of bamboo, while a high palm may allow the wind to just blow through.
Although we often get requests for high planters our standard leg heights are 21″, 31″, and 42″ plus a 1/2″ for the foot. This height allows for the standard height of the liner to accommodate 16-17” of soil, plenty for most plantings, while keeping the center of mass low. Aesthetically, it also allows the plant to be the focus of attention, instead of creating a wall of top-heavy looking planters. Lower heights also keeps costs down. If the intention in adding height is to screen a large space, our modular design includes a trellis accessory that combines rugged aluminum uprights and rustproof stainless steel mesh that will stand up to hurricane force winds, yet is not top-heavy.
Here in Florida, it is not possible to bring all the planters in off our large roof deck when a hurricane approaches. We have clips that can be mounted to the fasteners that hold the feet in the legs thus allowing the planter to be bolted to the deck. Many people, however, want to have the ability to move them about, or have rules or conditions that do not allow them to be bolted down so in extreme winds they may be blown over.
Because of these hurricane conditions, I have designed the planter liner to rest on aluminum straps suspended within the planter box. These not only ensure there is no funky accumulation of dirt or water to soil the deck under a planter, but if a planter should blow over and the planter liner blow out, the planter will not sail off the roof as it would if it had a solid bottom.
Roof Gardens: History, Design, and Construction
Theodore Osmundson (FASLA)
W.W. Norton & Company, 1999.
A wonderful resource for large green roofs in general and waterproofing, with a table of information about weights of materials (p. 296).
Fantastic sources of professional landscaping resources:
Landscape Architect and Specifier News (www.landscapeonline.com)
Landscape Architecture (magazine of the American Society of Landscape Architects – https://www.asla.org/
Garden Design (www.gardendesign.com)
Variflow Technologies, Inc. (www.Varicore.com) Multi-Flow professional drainage systems with very good information on drainage and preventing blockage using coarse grain sand. Their products are great for large drainage areas.