I really need to put my "Ultimate Neem Oil Guide" to paper and get it out of my head ...
Ok here goes.
First of all there are different types (brands) of Neem oil. I personally recommend "Garden Safe" brand "Neem Oil Extract" as it does NOT have the active ingredient azadirachtin that most other neem oils have, that can controversially end up in your end product, even if sprayed only in Veg.
First, this brand is readily available, easy to find at Walmart, Home Depot or Lowes.. Second, it's cheap. 3rd, it works, if you know what you're doing..
Number 1 rule of neem oil is NEVER EVER spray neem oil during the day or during lights on period. You MUST spray either at Dusk (outdoors) or JUST before lights out (indoor) to avoid "Neem Burn" - a condition caused by a reaction of the light and neem oil that will literally turn your leaves into crispy critters. So you need to allow time for the mixture to dry on the plant before the sun/light hits it.
Follow the recommended ratio on the bottle (Found under the label, in the "miticide" section) - should be approximately 2 to 4 tablespoons per gallon. For preventative measures I go 2 tbsp. - for extreme infestations go full strength 4 tbsp. per gallon. NEVER EVER more than that or you'll burn your plants.
Next, use WARM water (approximately 80-100 degrees) and make sure you constantly shake your sprayer as you are spraying to keep it mixed. Oil and water don't mix well.
Also use a wetting agent (coco-wet for instance) or this stuff -
https://www.thcfarmer.com/threads/in-search-of-cheaper-wetting-agents.141158/
Another rule - never spray neem in Flower!
Tip - If infestation of spider mites exists, make sure you spray the under side of leaves (as this is where they like to live and lay eggs), and gently massage the leaves and branches with your empty hand as you spray (helps knock off eggs and bugs)
Tip - spray once every 3 days if infestation exists - or once every other week for preventative.
I've been using this stuff for YEARS and if you follow these simple rules/tips you'll have no problems.
Personally, I stay away from any other brand neem oil especially the garbage made by Dyna-Gro.
I
f you have the money to spend, though, I HIGHLY recommend THIS STUFF as an alternative to NEEM -
https://www.amazon.com/Bio-Pesticide-All-Natural-Insecticide-Pesticide-Better-Insects-Non-Phytotoxic/dp/B07PH46H8K/ref=sr_1_1?crid=2JLMBYLUCVOXT&keywords=agro+magen+grow+safe+bio+pesticide&qid=1660526141&sprefix=agro+magen+grow+safe+bio+pesticid,aps,443&sr=8-1
Works WONDERS on just about every insect, AND won't kill bees!!!