It's amazing how fast you can fill up a potting shed or half a garage with garden products, especially if you never resist the urge to try every natural organic amendment available. For me, some work better than others; some don't seem to do anything at all.
But if I could have only one natural garden defense product, it would be a bottle of neem oil. This biologically beneficial product is pressed from the fruits and seeds of the neem plant (Azadirachta indica), an evergreen tree endemic to the Indian subcontinent.
Natural, cold-pressed neem oil has been used for medicinal and cosmetic purposes in India for thousands of years. Its many attributes include antiseptic, anti-inflammatory and antifungal properties. More significant to the discerning organic farmer and gardener, it has long been used as a natural biological defense for ornamental and food crops.
The principal active compound of the plant, azadirachtin, is a natural insect repellant, insecticide, miticide and fungicide. Several bioactive compounds are found in the leaves and other tissues of the neem tree. However, the seed kernels are the main source of azadirachtin, which also acts to discourage insects' feeding patterns while disrupting their growth and reproduction cycles.
This means that we can safely and effectively treat fungal diseases such as powdery mildew, black spot and rust on all indoor and outdoor plants, including flowerbeds, vegetables, herbs, trees, shrubs and all fruit and nut crops. I also find it more effective than many other natural products to wipe out sucking, biting and chewing critters, such as whiteflies, mealy bugs, thrips, spider mites and aphids -- even on extra-tasty bug delicacies, such as brugmansias, tomatoes and day lilies.
Wherever I manage to spray a neem oil solution consistently (yes, that is the key), it has been my superhero. Most amazingly, regular treatments appear to have stopped the dastardly cycle of spider mites on our Italian cypress and junipers. The natural vegetable oil is nontoxic to humans, birds, butterflies, earthworms, bees and pets.
Most package directions recommend a diluted mixture of 1 to 2 tablespoons of oil to a gallon of water. Apply to foliage and soil in a watering can to an isolated problem or use in a spray appliance to cover all plant surfaces in a larger area. I have found a handheld plastic spray bottle to be sufficient enough in this garden. Because the oil separates quickly, just like in salad dressing, the container needs frequent shaking between squirts.
As a preventive treatment, neem solution should be applied on a seven- to 14-day schedule. To control an existing problem, apply for seven days until the affliction is eliminated, followed by a maintenance spraying every 14 days until the potential for reinfestation is no longer present.
I have found bottled neem oil to be widely available in retail outlets of all sizes. But because of its many applications, it may be stocked in numerous categories. Ask for assistance when perusing a large garden center's inventory.