Neem oil can be used in an organic certified garden, it is my understanding that it (and other 'natural' products) are used extensively on organic crops.
In my opinion neem oil should only be used as a last resort, I personally use it mainly when having problem with the fruit trees rather than my vegetable crops.
Below are excerpts from various websites:
Neem oil also contains steroids (campesterol, beta-sitosterol, stigmasterol) and a plethora of triterpenoids of which azadirachtin is the most well known and studied. The azadirachtin content of neem oil varies from 300ppm to over 2500ppm depending on the extraction technology and quality of the neem seeds crushed.....
Formulations made of neem oil also find wide usage as a bio-pesticide for organic farming, as it repels a wide variety of pests including the mealy bug, beet armyworm, aphids, the cabbage worm, thrips, whiteflies, mites, fungus gnats, beetles, moth larvae, mushroom flies, leafminers, caterpillars, locust, nematodes and the Japanese beetle. Neem oil is not known to be harmful to mammals, birds, earthworms or some beneficial insects such as butterflies, honeybees and ladybugs. It can be used as a household pesticide for ant, bedbug, cockroach, housefly, sand fly, snail, termite and mosquitoes both as repellent and larvicide (Puri 1999). Neem oil also controls black spot, powdery mildew, anthracnose and rust (fungus)...
Studies done when Azadirachtin (the primary active pesticidal ingredient in neem oil) was approved as a pesticide showed that when neem leaves were fed to male albino rats for 11 weeks, 100% (reversible) infertility resulted.
Neem oil and other neem products such as neem leaves and neem tea should not be consumed by pregnant women, women trying to conceive, or children.
There is some evidence that heavy use may be associated with liver damage in children.
The bark, leaves and oil of the neem tree have been used in India for several thousand years, and are still used today.
About 75% of Ayurvedic remedies contain some form of neem! Indians call the sacred neem tree "the village pharmacy", and have limitless faith in its abilities.
Neem oil is used on humans, on animals, and on plants, for a huge range of different problems and diseases.
These are not just folk tales. Neem is the most heavily researched herbal remedy in India.
Scientists have identified over 150 active substances in neem, and many of those proved to be as effective in laboratory studies as the folklore claimed they would be.
Neem does most of what the salesman said, and more....
...Neem oil has many complex active ingredients. Rather than being simple poisons, those ingredients are similar to the hormones that insects produce. Insects take up the neem oil ingredients just like natural hormones.
Neem enters the system and blocks the real hormones from working properly. Insects "forget" to eat, to mate, or they stop laying eggs. Some forget that they can fly. If eggs are produced they don't hatch, or the larvae don't moult.
Obviously insects that are too confused to eat or breed will not survive. The population eventually plummets, and they disappear. The cycle is broken.
How precisely it works is difficult for scientists to find out. There are too many different active substances in neem oil, and every insect species reacts differently to neem insecticide.
Neem oil does not hurt beneficial insects. Only chewing and sucking insects are affected. It is certainly fascinating.
Like real hormones, neem oil insecticide works at very low concentrations, in the parts per million range. A little neem oil goes a long way.
But this is not something that happens over night. People spray neem oil as insecticide, and expect everything to die instantly, because that's what they are used to from chemical poisons. When that does not happen they conclude neem insecticide does not work.
It does work! Give it time to work. It's a much smarter way to deal with insect pests than to just kill everything.
I am from India, from a family of Ayurveda practitioners. I was using many medicinal plants for different things whilst I lived in India. About Neem and its uses - I have been using neem oil as a mosquito repellent, adding a drop with eucalyptus oil, as my young children can't stand the strong smell of neem oil on its own. I have been eating tender neem leaves for ages (more regularly in India, occasionally in Australia) as it is good to lower the effect of toxins in your body. Indians do eat tender neem leaves for the same purpose, but in the name of some festivals. A bunch of neem leaves hung around the house keeps the mozzies away. People affected with chicken pox are expected to lie in a special bed of neem leaves; smear the neem leaves paste on their bodies from the third day of the infection and then start to have a body wash with neem-soaked water for a period of 10 days. Neem, turmeric, tulsi and a number of such plants and trees are part of our everyday life in a number of forms and uses.
Thanks for sharing that, I didn't realise it had so many uses. When I posted this I was in a hurry but the information on one of the web sites was astounding and I have book marked it for future reference when I get a bit of spare time.
O WOW...thanks Donna. I havent used my oil yet...been a bit confused in what to do with it heehee.
but this is great....ive been meaning to ask, whats the mix ratio. (and i would like to use, on my fruit tree, as it seems alot more better but not 100% as it should be, thought i might get fruit but NOPE...maybe next season?)