Wednesday, August 21, 2013


The Mantis (praying mantis) is an effective predator and usually a welcome insect in organic gardening. There are many species of mantis in temperate and tropical climates worldwide.

The mantis is able to see up to 20 meters and has precise stereoscopic vision up close. They possess the unique ability to turn their heads 180º, and use this ability to determine the relative distance of their prey. They wait motionless, relying on camouflage to conceal their presence while other insects wander close enough to reach. They strike within 30 to 50 thousandths of a second with incredible accuracy, and can even snatch flies and mosquitoes from the air. They hold their prey in their barbed forelimbs while they eat them alive. Mantids sometimes prey on animals much larger than themselves.

Mantids usually fly at night, when they are least vulnerable to natural predators like birds. They can hear and avoid the echolocation sounds made by bats. They are non-venomous and have no chemical defenses to discourage other animals from eating them.

Whether the mantis is useful in gardens depends on the intention of the gardener. Mantids prey on any insect they can catch including beneficial insects and other mantids. The common belief that a female mantis will devour her mate is a habit most often observed in captivity when the female is hungry. In the wild, males are very cautious around hungry females.

The mantis is most closely related to roaches and termites. They lay eggs in clusters of 10 to 400 eggs that are available for purchase at garden supply stores. Mantis nymphs, emerging from eggs look similar to adult mantids and often mimic ants. If prey is not immediately available, the nymphs will cannibalize each other. The typical life span of a mantis is 10 to 12 months.

Mantis on a papaya. Photo credit Nate Porter.


Thursday, August 15, 2013


Phosphorus is an essential macro-nutrient for plants and all life on earth. Phosphorus is a component of nucleic acids, ATP and the phospholipid bi-layer that encloses cells.

Phosphorus is a scarce finite resource on planet earth. It is extracted from phosphate rock almost entirely for agriculture use around the world. There are organic and synthetic processes of phosphate extraction in mineral mining.

When is the earth-destructive process of mineral extraction qualified as organic? This has to do with chemicals used in the chelation process of making absorbable phosphate fertilizers from rock. Synthetic chelates like EDTA or DTPA used to strip phosphates from rock appear in trace amounts in non-organic produce grown with synthetic fertilizers. Organic chelates are humic or fulvic acids derived from the natural decomposition of organic material. The phosphates recovered by humic acids are identical to those found in nature.

Optimistic scientists say we have more than 100 years before the end of agriculture (and strike-matches technology). Recycling phosphorus by using manure or animal bones as a source for phosphorus fertilizer on local farms is the approach used by permaculturists. Phosphorus conservation for urbanites and suburbanites can be achieved with hydroponics.

Phosphoric acid is often used in hydroponics to bring the pH of a nutrient solution down.
Plant Nutrition Facts
Phosphorus (P)
Absorbable Forms H2PO4- and HPO42-
Fertilizers Phosphoric acids, super-phosphate, ammonium phosphate, phosphogypsum, apatite, animal waste, bone meal, algae
Symptoms of Deficiency Plant is dark green with purple veins and stunted; burned leaf tips
Necessary in the synthesis of ATP, phospholipids in cell walls and nucleic acids. Promotes growth of roots and shoots.
Plant Nutrition
Phosphorus is necessary during all stages of plant growth. Plants need more phosphorus during periods of advanced expression: blooming and fruiting.
Synthetic: Extracted from phosphate rock using synthetic chelates that appear in trace amounts in non-organic produce.

Organic: (1)Extracted from phosphate rock using organic chelates like humic acids. Identical to phosphates naturally occuring in soil. (2)Recovered from bone meal, guanos, urine or algae.
Adverse Effects
Mineral sources of phosphorous may contain trace amounts of toxic heavy metals like cadmium, flouride, uranium, radium or polonium. Synthetic phosphates contain trace amounts of synthetic chelates. Phosphate fertilizers leaching into aquatic environments promote algae blooms that kill fish. Flourine, as a component of super-phosphates, contributes to soil sterilization.

Tuesday, August 13, 2013

Lady Beetles

Beetles of the family Coccinellidae called Lady Beetles, or Lady Bugs in most of North America, are important insects worldwide. Lady beetles are a favorite insect in cultures on every continent. These beetles have often appeared in old stories, poems and children’s literature possessing virtues associated with good nature and luck. For gardeners they provide effective pest-control of aphids and other harmful insects.

Lady beetles and their larvae prey on aphids and scales. Some species even prey on caterpillars or spider mites.  

The lady beetle lays eggs near their prey that hatch in 5 - 7 days. The larvae emerge with six prominent legs on the upper torso and a distinct lady-beetle head and mouthparts. The larval period lasts around 2 weeks then larvae find a spot to fix themselves for pupation and begin the transformation to an adult lady beetle. The pupation stage lasts 5 to 8 days before the beetle emerges with a soft and less-colorful exoskeleton that will become more colorful as it hardens.

Lady beetle larvae on chamomile
Lady beetle pupae

An adult lady beetle will live 1 to 2 years. Within a year they can have as many as three generations of offspring. They find a warm and protected place to enter dormancy during the winter. This is the reason lady beetles begin to invade homes in the late autumn. Most lady beetles for-purchase from a garden supply store, nursery or online are collected from one species that aggregate for winter in higher-elevation areas of California. 

Lady beetles produce an alkaloid toxin giving them an acrid taste to predators. Their flashy red coloring serves as a reminder to predators not to eat them. Lady beetles may also “reflex bleed” when physically disturbed and force the toxin out from their joints as an appetite-deterrent. The term “ladybird taint” refers to the flavor of wine when ladybird beetles have found their way into the process.

The harlequin lady beetle from Asia was established in the United States in 1988 for aphid control, and has since spread to most of the United States and Western Europe. This species has displaced many native populations of lady beetles, but is uniquely effective against soybean aphids, another invasive species from Asia.

Lady beetles may occasionally bite people. Although the bite is described as only mildly irritating, it can cause some people to have an allergic reaction.

Introducing lady beetles into your garden will more than likely benefit your neighbors. Lady beetles tend to disperse when released. They are not likely to reproduce for weeks while they feed and recover from the stress of relocation. Keeping one plant with aphids in a location away from the garden may improve the likelihood of keeping lady beetles in the area. Lady beetles are compatible with many natural pest-deterrents like soaps, neem and herbal oils.

Original photos by Nate Porter.


Wednesday, August 7, 2013


Nitrogen (N) is one of the essential building blocks of nucleotides for DNA and RNA and of amino acids for proteins. Nitrogen is necessary for all of life on earth. For plants, nitrogen is the limiting factor for growth and the primary ingredient in fertilizer. Plant’s can only absorb nitrogen as ammonia (NH3) or as nitrate (NO3). These molecules are relatively scarce compared to atmospheric nitrogen (N2) that makes up 78.09% of earth’s atmosphere. 

Before 1913, all of the nitrogen in plants and animals was produced by organic bacteria with special enzymes that convert atmospheric nitrogen to absorbable forms. Today more than half of the nitrogen in our bodies was produced industrially from fossil fuels using a synthetic process of Nitrogen fixation. Industrial nitrogen fertilizers are a major source of environmental pollution.

The nitrifying reactions of bacteria
Atmospheric nitrogen to ammonia:
N2 + 8H+ + 8e- => 2NH3 + H2
Ammonia to nitrite by Nitrosomonas bacteria:
2NH3 + 3O2 => 2NO2 + 2H+ + 2H2O
Nitrite to nitrate by Nitrobacter bacteria:
2NO2- + O2 => 2NO3-
Ammonia is the first product of nitrogen fixation by bacteria called diazotrophs using the enzyme nitrogenase. These bacteria are abundant in low-oxygen environments like soil, mud and decomposing organic materials. Urea, a component of animal urine is also metabolized by bacteria with the enzyme urease to produce ammonia. Ammonia is a weak base and reacts with acids to form ammonium (NH4+) salts. The ammonium ion in water is readily available for absorption by plants.

Nitrosomonas bacteria convert ammonia to nitrite, which is not a form of nitrogen available to plants. Nitrobacter bacteria convert nitrite to nitrate which is available to plants.
Plant Nutrition Facts
Nitrogen (N)
Absorbable Forms Nitrate (NO3-) and Ammonium (NH4+)
Fertilizers ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, urea
Symptoms of Deficiency Oldest leaves turn yellow and die prematurely; plant is stunted
Necessary for the synthesis of proteins and nucleic acids. Nitrogen is the limiting factor of vegatation and growth.
Plant Nutrition
Plants need nitrogen throughout the grow cycle. Plants use more nitrogen during the vegetative stage to grow and produce leaves. Plants use less nitrogen when flowering and fruiting.
Synthetic: The major source of industrial nitrogen fertilizer is anhydrous ammonia: a chemical gas most abundantly derived from non-renewable fossil fuels.

Organic: Nitrogen is made available organically through decomposition by nitrogen-fixing bacteria in soil. Organic fertilizers use natural sources for nitrogen like animal waste or composted materials.


Monday, August 5, 2013


Aphids are despised by farmers in temperate climates worldwide and for obvious reasons. Aphids will reproduce quickly on certain plants until the stem and leaves are covered in these plump squishy insects. They feed by piercing a plant with sharp mouth parts and sucking sugar-rich fluid from the phloem where sugars are transported. Not only does this starve the plant, but aphids also introduce pathogens like viruses.  

Aphids use a simple but effective defense to escape predators. When an aphid is attacked or under duress it ejects an alarm pheromone from exhaust-pipe looking features protruding from the back called cornicles. This is a signal to other aphids to drop off of their leaf or stem. A once-successful predator that gets marked by the alarm pheromone will have less success catching more aphids.

While the apparent natural defense of an aphid is to simply let go of whatever it is they are attached to, they have another fierce arthropod ally. Certain species of ants will actively farm aphids for their sweet digestive waste called honeydew. These farming ants will manage herds, and even carry aphid eggs underground to nest with their own during the winter. Most importantly, ants defend aphids from other predators like lady beetles and their larvae.  

The first thing to do if a plant is infested with aphids is to wash them off thoroughly with water. Most of the displaced aphids will not find their way back to the plant. Water also washes away the sticky, sugary honeydew that feeds mold. To prevent aphids from recolonizing a plant, spray the plant with an adequately-diluted mix of soapy water and any variety of herbal oils that have been shown to deter insects.

Control ants in the area that may be actively re-establishing the aphids on plants. Check the area around your garden for weeds that harbor aphid colonies like mustards and sowthistle. Aphids can also thrive on the newer growth in the inner branches of trees. Natural predators of aphids like lady beetles (ladybird beetles, lady bugs) can be purchased at a local gardening store or online.


Monday, April 15, 2013

Light for Plants

The absorption of chlorophyll a and b in a solvent. source
Botany is complex. Not every chemical reaction in photosynthesis is understood. What we have learned about plants and light has evolved the standards and design of high-tech agriculture lighting. This is a summary of the colors plants absorb and how they respond to them. (I will be happy to elaborate about any subject mentioned here that needs more explanation in the comments!)

Sunlight appears more red in autumn and winter as the sun rises lower on the horizon. Sunlight must pass through more of earth's atmosphere during these seasons and blue light is reflected away. This is also why sunsets are red or gold colored. Many plants are sensitive to an increase in red light as a signal to begin flowering before winter. In spring, as the sun rises higher in the sky, more blue light penetrates the atmosphere allowing the spring surge of vegetation.

There are 3 groups of plants based on their responses to light: Long Day Plants, Short-Day Plants and Day-Neutral plants. In each of these categories it is the duration of darkness(not light) that stimulates a response from plants.
  • Long-day plants flower in the spring as days are getting longer and sunlight is more blue. Lettuce, peas, turnips, wheat, clover, and carnations are varieties of long-day plants.
  • Short-day plants blossom in the autumn or late-autumn in the northern hemisphere as the duration of darkness increases and sunlight is increasingly red(after June 21). These plants require uninterrupted periods of darkness and do not flower if their night-time periods are interrupted by several minutes of light. These include plants like coffee, chrysanthemums, strawberries, corn, cotton, hemp, rice and sugar cane.
  • Day-neutral plants respond to some other stimulus than light to initiate stages of development. They may respond to changes in temperature, nutrient availability or achievements in developmental maturity. These include plants like cucumbers, roses and tomatoes.
For short-day plants, increasing exposure to red light will provoke flowering just as a change in season(summer to autumn) would. Long-day and neutral plants don't need an increase in red light to flower and will continue to mature under blue light. By changing the duration, spectrum and intensity of exposure with indoor lighting, botanists can control the stages of vegetation, flowering and fruiting.

Plants use many pigments to absorb and react to light. Pigments are divided by their purpose into three categories: phototropins, cryptochromes and phytochromes.

Phototropins are pigments that allow plants to respond to light by affecting the curvature of growth, the triggering of stomatal(pores) opening or developmental changes. Phototropins are the reason plants bend towards light and react in many other ways to light exposure.

Cryptochromes absorb light in the blue spectrum specifically at 380nm and 450nm (pterin, flavin). These pigments mediate phototropism, circadian rhythms and gene expression. Blue light promotes stem elongation, and leaf expansion. Cryptochromes are targeted in the vegetation stage of indoor agriculture with metal halide grow bulbs or other blue-light bulbs.


Phytochromes absorb red(650-670nm) and far-red(705-740nm) light. The color of these pigments alternate in response to the absorption of light. (Exposure to red light changes the phytochrome to preferentially absorb far-red light, while far-red light changes the phytochrome back to absorb red light again.) Gene signalling and expression are driven in the far-red stage of absorption. Without both red and far-red light, plants will become developmentally stunted. Light bulbs like high pressure sodium provide light in the red and far-red spectrum to stimulate short-day plant maturation and flowering.


The apparent(visible) colors of plants are complementary to the colors of light they absorb. The complementary color of absorbed light is the actual color of the plant pigment(s).

Pigments as complements to absorbed light.
absorbed λ absorbed color complementary color
These colors are based on peak values expressed in hexadecimal color.

Indoor Lighting for Agriculture
High Intensity Discharge(HID) light systems use bulbs like metal halide and high-pressure sodium. These systems have an effective light distribution and are the most widely-used for indoor agriculture. They also use more energy and release more heat than alternative agriculture lighting. HID's require a Socket, Ballast & Bulb.

Hoods and reflectors are fixtures that protect and insulate bulbs. Many are designed to be fitted with ventilation ducting to remove heat. Most hoods contain sockets that will take both MH and HPS bulbs from 250 to 1000 watts.

Digital Ballasts  |  Magnetic Ballasts
Ballasts convert the energy supply to a frequency that will light an HID Bulb. Some magnetic/analog ballasts are designed specifically for MH or HPS bulbs, while digital ballasts accept both. Conversion bulbs are made to be cross-compatible with ballasts designed specifically for MH or HPS bulbs. The wattage of the bulb and ballast must match.

MH Bulbs  |  HPS Bulbs
Metal Halide (MH) bulbs provide more blue light for the Grow, or vegetative stage that begins a plant's life cycle.
High Pressure Sodium (HPS) bulbs provide more red light for the Bloom, or flowering stage at the end of a plant's life cycle.
Please consider all of your energy usage in amps to grow safely with indoor bulbs. Read more: Power Capacity

Alternative Lighting

Fluorescent lighting includes T5 high output and compact fluorescent lighting. These are common because they produce little heat, require less energy and produce reasonably high light output. Compared to HID lighting, plants do not grow as tall beneath the lower intensity of fluorescent lighting.

Light Emmiting Diodes(LEDs) are low-energy, low-heat, long-lived color-specific bulbs used most often in electronics. They are now used in indoor agriculture as a color-specific supplement to stronger light sources. LEDs strong enough to grow plants are less efficient and generate more heat than flourescents with the same output.

The most common function of lighting controllers is to automate the day-night cycle of an indoor garden. Basic timers are inexpensive and worth the money to avoid manually regulating a grow cycle. Specific controllers have many uses, like delaying the power when a bulb is switched on to prevent situations like a hot-start. Multi-system controllers may regulate temperature, CO2 and humidity in addition to high-intensity lighting. These controllers have multiple programmable outlets, but are ultimately limited by the circuit capacity.

New Lighting Technology
Science continues to provide new solutions for indoor agriculture lighting. While new lighting technology is usually more expensive, the cost is offset by lower energy requirements and longer-lasting bulbs. We keep an eye on new energy-efficient lighting systems and their availability in agriculture.

*This content is published with modification on our main website:

-->don't knock wiki sources

Wednesday, April 10, 2013

Organic Hydroponics

papaya grown in soil with organic nutrients under T5 lighting

I want to defend organic nutrients, but not the word organic. We're learning not to trust the word "organic" the way we demoted the word "natural" to a synonym of "anything". As in: 'anything you can sell is natural.' Some of our nutrient brands have gone a step further to describe their products as "vegan" to emphasize that they are using non-mined plant sources like seaweed. It's important to understand that hydroponic systems for agriculture conserve more water, energy and mineral resources than open industrial farming by a long shot.

Phosphorus is the reason we have a problem labeling any fertilizer organic. Phosphorus is a scarce finite resource on planet earth. It is an essential element for life, and is extracted from phosphate rock almost entirely for agriculture use around the world. There are organic and synthetic processes of phosphate extraction in mineral mining.

When is the earth-destructive process of mineral extraction qualified as organic? This has to do with chemicals used in the chelation process of making absorbable phosphate fertilizers from rock. Synthetic chelates like EDTA or DTPA used to strip phosphates from rock appear in trace amounts in non-organic produce grown with synthetic fertilizers. Organic chelates are humic or fulvic acids derived from the natural decomposition of organic material. The phosphates recovered by humic acids are identical to those found in nature.

Optimistic scientists say we have more than 100 years before the end of agriculture (and strike-matches technology). Recycling phosphorus by using manure or animal bones as a source for phosphorus fertilizer on local farms is the approach used by permaculturists. Phosphorus conservation for urbanites and suburbanites can be achieved with hydroponics.

Many nutrients labelled 'organic' are made for soil, and include nutrients that promote living microflora. This is technically not hydroponics. Hydroponics, by definition, uses inert soilless mediums that allow easy nutrient exchange with the roots of plants. Soil is increasingly popular in urban gardening because of the benefits of microflora. Plants grown in soil are more resilient to everything. Beneficial microbial life in the soil create these organic chelates (humic acids) that continue to make phosphates and other minerals in soil available to plants for absorption.

Whether the system is hydroponic or soil, in full sunlight or beneath powerful grow-lights, the principles of plant nutrition are the same. If you can identify and abundantly provide the minerals plants need during different stages of growth, the plants will grow large and produce a lot of food. This works in soil as well with the use of organic nutrients.

There are nutrients designed specifically for growth, blooming, fruiting, and as targeted adjustments to mineral deficiencies in plants. There are enzyme catalysts , micro-flora cultures, and amendments for every imaginable application. Insect frass, for example, is insect material that is both a fertilizer, and a trigger for plants to produce their own natural pest-deterring immune response.

Hydroponics is water-efficient. Many systems recycle nutrients until the fertilizer is spent. Even nutrient wastewater from non-organic, or mineral-derived nutrients used in hydroponics is cleaner than grey water from laundry machines and dishwashers. If you live in an area with municipal water treatment, dumping your waste nutrients down the drain makes extra food for the microbes used in water reclamation. The city might notice a bump in organic activity (a proper use for the word organic) at their treatment facility. Some ethically-minded growers make their own ponds to reclaim nutrient wastewater.

Fertilizers that wind up in lakes and rivers produce algae blooms that can suffocate fish and destroy ecosystems. Even organic nutrients will feed algae blooms. This is a manageable problem for industry-scale hydroponics but not for high-input farming. High-input farming has no efficient way to recover, recycle or reclaim the chemical fertilizers and pesticides required to sustain those operations. Fertilizer run-off is devastating to ecosystems as seen here in Florida's toxic algae

If organic is a standard based on input (no chemical fertilizers, synthetic pesticides, etc.), is a tomato grown organically in California still organic in Washington? We can describe produce as 'local and organic', but 'organic' farming is as unsustainable as the farming industry ever was. Sustainable agriculture is local and resource-efficient. This is why we promote hydroponics. 

Sources not linked above:

--> don't knock wiki sources.