Community Garden #4- Neem Oil and Humboldt Nutrients “Sticky” Wetting Agent

687474703a2f2f656e7472657072656e65757273696e6a616d616963612e636f6d2f77702d636f6e74656e742f75706c6f6164732f323031312f30392f6e65656d2d747265652e6a7067What is neem oil?

“Neem oil is a naturally occurring pesticide found in seeds from the neem tree. It is yellow to brown, has a bitter taste, and a garlic/sulfur smell. It has been used for hundreds of years to control pests and diseases. Components of neem oil can be found in many products today. These include toothpaste, cosmetics, soaps, and pet shampoos. Neem oil is a mixture of components. Azadirachtin is the most active component for repelling and killing pests and can be extracted from neem oil. The portion left over is called clarified hydrophobic neem oil.”[1]

How does neem oil work?

“Neem oil is made of many components. Azadirachtin is the most active. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed. However, the exact role of every component is not known.”[2]

For the communardener, I think neem oil is a great way to provide preventative insect and disease suppression through regular foliar applications. “Foliar applications” is a fancy way of saying to spray your plants stems and leaf surfaces with a hand held spray bottle, garden pump sprayer, or a more fancier Silicon Valley type device which has computer chips and what not, and a water dilution of the pure neem oil.

PUMP_UP_SPRAYERS_img_1 32oz bottle sprayerHand-Sprayer-pump

Usually, a hand held spray bottle or basic pump sprayer is plenty good enough for your run of the mill communardener and since it needs to be done regularly, it’s ok to spray in sections if need be, as opposed to getting them all at once. A very important addition to your foliar application of neem oil is a wetting agent to help the efficacy and applicability.

What is a wetting agent?


“Wetting agents are substances that reduce the surface tension of water to allow it to spread drops onto a surface, increasing the spreading abilities of a liquid. Lowering the surface tension lowers the energy required to spread drops onto a film, thus weakening the cohesive properties of the liquid and strengthening its adhesive properties.”[3]

Humboldt Nutrients Premium Wetting Agent is called “Sticky”. We recommend using Sticky with every foliar application of neem oil. Sticky will help you get the most out of your neem spray and a little bit goes a long way. Sticky can be used at a 1/2oz.-1oz. per gallon of neem solution(check below for application rates for 1 gallon of neem spray).

When applying your neem spray to your garden bed and plants make sure, “NOT TO SPRAY PLANTS IN PEAK HEAT OF DAY, OR HEAVY SUNLIGHT”. The best times to spray your plants is in the early morning or late evening. When spraying your plants, make sure they are coated evenly, top and bottom of all leaf surfaces and stems. There is no special way to do that. Spray them until they are dripping. Again, make sure you spray the underside of your leaves as well as the tops, and the base of your stems all the way to the tops. Do not worry about overspray or dripping of neem on your soil, as it is beneficial to soil health as well. While spraying your plants make sure to give your spray bottle or pump sprayer a good shaking periodically as you are moving along, so as to make sure that your solution stays nicely mixed up as you spray.

Regularity is the key to natural pest and disease prevention. I have found that a once a week foliar application of neem oil throughout the early growth stages and early flowering stages is effective for all pest and disease prevention needs. It really is all you need to do. I have found that every other week is ok as well, and sometimes even less. The key is to be diligent and do it regularly early on.

There are other natural pest and fungicide sprays that you can find out there and I do not discourage use of other products. I just like neem and Humboldt Nutrients Sticky wetting agent for affordability, efficacy, safety, and ease of use. Neem and Sticky are my “Old Shoe” of horticultural pest and disease prevention. I think it should be in every communardener’s tool belt.


Until next time!


Neem Spray Solution=

1-gallon Clean Chlorine Free Water
1/2oz-1oz. Pure Neem Oil
1/2oz-1oz. Humboldt Nutrients Premium Wetting Agent Sticky

*add ingredients one at a time stirring thoroughly after each addition and remembering to shake container periodically while spraying to stay mixed. Neem spray should be applied weekly or bi-weekly for best results*



[1] Neem Oil General Fact Sheet, National Pesticide Information Center,
[2] Neem Oil General Fact Sheet, National Pesticide Information Center,
[3] Wetting Agents, UC Davis Chemwiki,