nuggdigger
04-12-2007, 06:16 AM
VERTICAL AND ROTATING GARDENS have become a relatively common sight in today’s hydroponics shops. Although more recently popularized, the concept has been around for some time. The Hanging Gardens of Babylon were one of the seven wonders of the old world and were described by Diodorus Siculus, a Greek historian, in the following way:
“The approach to the Garden sloped like a hillside and the several parts of the structure rose from one another tier on tier.... On all this, the earth had been piled...and was thickly planted with trees of every kind that, by their great size and other charm, gave pleasure to the beholder.... The water machines [raised] the water in great abundance from the river, although no one outside could see it.”
Though vertical gardens can be a thing of beauty, more important, for the purposes of gardening with artificial lighting, they can be extremely productive per square foot of floor space occupied. Vertical and rotating gardens have been popularized with a variety of designs. Most designs promote equidistant lighting as a primary benefit for overall crop quality and consistency. As most HID lighting offers a 360-degree pattern of illumination, it makes sense to wrap the garden around the light source. Conventional gardens aim to redirect HID light into a linear pattern to deliver it to the plant canopy. Though reasonably effective, a considerably larger area of square footage is required when delivering HID lighting in a linear pattern.
For example, as a rule of thumb one 1000-W HID lamp is suspended 18 in. (~46 cm) above the plant canopy to illuminate an area of 4 x 4 ft. (120 x 120 cm) in a conventional garden. In a vertical garden, the arrangement is typically cylindrical in shape, as will be our calculations. Stick with me here. So, 18 in. of lamp-to-canopy tolerance translates into a 3-ft. (90-cm) diameter (think circle). Most vertical gardens require little vegetative growth and plants finish at relatively shorter “heights,” say, on average 18 in. That means we have to wrap 18 in. in finished plant height around a 1000-W HID lamp while leaving about 18 in. of lamp-to-plant canopy clearance.
Diameter = radius x 2
Circumference = (pi) x diameter
The diameter resulting from the arrangement suggested above would be 6 ft. (~2 m), i.e., (18 in. x 2) + (18 in. x 2), so, 6 ft. x 3.14 = 18.84 ft. (~6 m). Already we have more surface area (square footage) than our conventional garden (16 sq. ft. or ~1.4 m2), but it goes further. Our cylindrical garden stands about 4 ft. tall, so we must multiply 18.84 (square footage/diameter) x 4 (garden height) to get a total surface area/square footage of about 75 sq. ft. (~7 m2).
In the end, this translates into about five times the area for plant material to be brightly lit than a conventional garden. However, this is just math and not the real world. There are many other factors to be considered, including the fact that 1000-W HIDs are often not the wattage of choice for vertical gardens. However, the above does exemplify that vertical gardens, particularly cylindrical gardens, may offer significantly greater yield advantage potential per square foot of floor space occupied, as well as per watt of HID lighting used. The rotating models offer the additional benefit of minimizing shadows. The fact that the plants will receive some light on their undersides in rotating gardens helps the plants remain more compact and consistent in finish from top to bottom of the stem.
In a day and age where square footage and electricity are becoming increasingly expensive, the additional initial investment associated with manufactured vertical gardens may be offset with their increases in productivity and efficiency.
Air movement, temperature, and carbon dioxide levels may also be more uniform in the plant canopy using vertical and rotating gardens. Stationary vertical gardens also take advantage of the natural tendency for heat to rise. Essentially, a cylindrical vertical garden may become like a rather large duct for air movement. If fresh CO2 supplemented air is drawn from the bottom of the garden and discharged by fans straight up, all plants in the garden receive relatively even air quality and temperatures while remaining in a constant breeze. This helps provide uniformity in growth pattern, an important consideration in any HID-lit garden, but increasingly critical in vertical gardens.
Air-cooling of HID lighting is also simplified in this fashion. Multiple lamps may be suspended over top of the other; the height of the garden is simply increased proportionately with the addition of lamps. A tremendous advantage to vertical gardens is that when increases in production levels are required, the grower may simply build up, meaning that the square footage of floor space can remain the same while increasing vertical height to expand the garden.
There are also special considerations in growing protocol where vertical gardens are concerned. Typically, vertical and rotating gardens will require large numbers of plants. Plants must grow relatively short to take advantage of the efficiency using equidistant lighting, so side branching is minimized and avoided. As a result, the wrap-around effect of the garden is based more on a sea-of-green type of approach to plant heights and spacing. For example, a vertical garden with a 6-ft. (~2-m) diameter and an overall height of 6 ft. using two 1000-W HID lamps or three 600-W HID lamps may house in the range of 350 plants per crop — a commercial propagators dream!
It is very important to maintain uniformity in vertical and rotating gardens. The design of such gardens tends to promote this tendency; however, the genetics used must be selected carefully for these gardens to offer their maximum efficiency. For production-minded gardens, all plantings should be of the same variety. In fact, they should be from the same plant. Some growers using rotating gardens in Quebec, Canada noticed significant increases in their yields when all of the cuttings planted were from the same main plant, not just the same variety. They attributed this to uniformity in growth. Slight variations in plant vigor may become amplified, diminishing uniformity in vertical and rotating gardens.
Strains that have a natural tendency to produce compact plants are best suited for vertical and rotating gardens, particularly those that do not exhibit much vertical growth after initiating the flowering cycle. The grower needs to know just how many inches of growth to expect to maturity once changing to the critical lighting cycle for flowering. Remember that the lights will remain stationary.
Plants can be manipulated to remain shorter in stature through a variety of cultural practices, including controlling the nutrient and additive regimen, the day/night temperature differentials, the air movement, and the lighting. Nutrients that contain lower nitrogen levels, particularly with little or no nitrogen in the ammonium form, are best suited. Organic nutrients may also work well in vertical gardens. There are chemical additives that may be used to keep internodal distances at a minimum at the onset of flowering. Additional additives can be used once structural growth has stopped, typically four weeks after initiating the flowering cycle.
The fact that the plants grown in these types of systems are often just single stems makes processing the crop expedient and efficient. The overall quality of produce and inflorescence tends to be very consistent. Crop turnaround and planting time vary with the different models available. Although systems that are more media-based tend to take longer to prepare for successive crops, the increased volume of substrate helps to buffer nutrients, temperatures and pH at the root zone, contributing to healthier and happier harvests.
“The approach to the Garden sloped like a hillside and the several parts of the structure rose from one another tier on tier.... On all this, the earth had been piled...and was thickly planted with trees of every kind that, by their great size and other charm, gave pleasure to the beholder.... The water machines [raised] the water in great abundance from the river, although no one outside could see it.”
Though vertical gardens can be a thing of beauty, more important, for the purposes of gardening with artificial lighting, they can be extremely productive per square foot of floor space occupied. Vertical and rotating gardens have been popularized with a variety of designs. Most designs promote equidistant lighting as a primary benefit for overall crop quality and consistency. As most HID lighting offers a 360-degree pattern of illumination, it makes sense to wrap the garden around the light source. Conventional gardens aim to redirect HID light into a linear pattern to deliver it to the plant canopy. Though reasonably effective, a considerably larger area of square footage is required when delivering HID lighting in a linear pattern.
For example, as a rule of thumb one 1000-W HID lamp is suspended 18 in. (~46 cm) above the plant canopy to illuminate an area of 4 x 4 ft. (120 x 120 cm) in a conventional garden. In a vertical garden, the arrangement is typically cylindrical in shape, as will be our calculations. Stick with me here. So, 18 in. of lamp-to-canopy tolerance translates into a 3-ft. (90-cm) diameter (think circle). Most vertical gardens require little vegetative growth and plants finish at relatively shorter “heights,” say, on average 18 in. That means we have to wrap 18 in. in finished plant height around a 1000-W HID lamp while leaving about 18 in. of lamp-to-plant canopy clearance.
Diameter = radius x 2
Circumference = (pi) x diameter
The diameter resulting from the arrangement suggested above would be 6 ft. (~2 m), i.e., (18 in. x 2) + (18 in. x 2), so, 6 ft. x 3.14 = 18.84 ft. (~6 m). Already we have more surface area (square footage) than our conventional garden (16 sq. ft. or ~1.4 m2), but it goes further. Our cylindrical garden stands about 4 ft. tall, so we must multiply 18.84 (square footage/diameter) x 4 (garden height) to get a total surface area/square footage of about 75 sq. ft. (~7 m2).
In the end, this translates into about five times the area for plant material to be brightly lit than a conventional garden. However, this is just math and not the real world. There are many other factors to be considered, including the fact that 1000-W HIDs are often not the wattage of choice for vertical gardens. However, the above does exemplify that vertical gardens, particularly cylindrical gardens, may offer significantly greater yield advantage potential per square foot of floor space occupied, as well as per watt of HID lighting used. The rotating models offer the additional benefit of minimizing shadows. The fact that the plants will receive some light on their undersides in rotating gardens helps the plants remain more compact and consistent in finish from top to bottom of the stem.
In a day and age where square footage and electricity are becoming increasingly expensive, the additional initial investment associated with manufactured vertical gardens may be offset with their increases in productivity and efficiency.
Air movement, temperature, and carbon dioxide levels may also be more uniform in the plant canopy using vertical and rotating gardens. Stationary vertical gardens also take advantage of the natural tendency for heat to rise. Essentially, a cylindrical vertical garden may become like a rather large duct for air movement. If fresh CO2 supplemented air is drawn from the bottom of the garden and discharged by fans straight up, all plants in the garden receive relatively even air quality and temperatures while remaining in a constant breeze. This helps provide uniformity in growth pattern, an important consideration in any HID-lit garden, but increasingly critical in vertical gardens.
Air-cooling of HID lighting is also simplified in this fashion. Multiple lamps may be suspended over top of the other; the height of the garden is simply increased proportionately with the addition of lamps. A tremendous advantage to vertical gardens is that when increases in production levels are required, the grower may simply build up, meaning that the square footage of floor space can remain the same while increasing vertical height to expand the garden.
There are also special considerations in growing protocol where vertical gardens are concerned. Typically, vertical and rotating gardens will require large numbers of plants. Plants must grow relatively short to take advantage of the efficiency using equidistant lighting, so side branching is minimized and avoided. As a result, the wrap-around effect of the garden is based more on a sea-of-green type of approach to plant heights and spacing. For example, a vertical garden with a 6-ft. (~2-m) diameter and an overall height of 6 ft. using two 1000-W HID lamps or three 600-W HID lamps may house in the range of 350 plants per crop — a commercial propagators dream!
It is very important to maintain uniformity in vertical and rotating gardens. The design of such gardens tends to promote this tendency; however, the genetics used must be selected carefully for these gardens to offer their maximum efficiency. For production-minded gardens, all plantings should be of the same variety. In fact, they should be from the same plant. Some growers using rotating gardens in Quebec, Canada noticed significant increases in their yields when all of the cuttings planted were from the same main plant, not just the same variety. They attributed this to uniformity in growth. Slight variations in plant vigor may become amplified, diminishing uniformity in vertical and rotating gardens.
Strains that have a natural tendency to produce compact plants are best suited for vertical and rotating gardens, particularly those that do not exhibit much vertical growth after initiating the flowering cycle. The grower needs to know just how many inches of growth to expect to maturity once changing to the critical lighting cycle for flowering. Remember that the lights will remain stationary.
Plants can be manipulated to remain shorter in stature through a variety of cultural practices, including controlling the nutrient and additive regimen, the day/night temperature differentials, the air movement, and the lighting. Nutrients that contain lower nitrogen levels, particularly with little or no nitrogen in the ammonium form, are best suited. Organic nutrients may also work well in vertical gardens. There are chemical additives that may be used to keep internodal distances at a minimum at the onset of flowering. Additional additives can be used once structural growth has stopped, typically four weeks after initiating the flowering cycle.
The fact that the plants grown in these types of systems are often just single stems makes processing the crop expedient and efficient. The overall quality of produce and inflorescence tends to be very consistent. Crop turnaround and planting time vary with the different models available. Although systems that are more media-based tend to take longer to prepare for successive crops, the increased volume of substrate helps to buffer nutrients, temperatures and pH at the root zone, contributing to healthier and happier harvests.