You can use any full spectrum nutrient to foliar feed your plants. To avoid nutrient burn, your nutrient solution strength, should be no more than 1/3rd of the maunufactures reccomended dosage.
* The best temperature is about 72 degrees (when stomata on the underside of the leaves are open); at over 80, they may not be open at all. So, find the cooler part of the day if it is hot and the warmer part of the day if it is cold out.
* Use a good quality sprayer -- should atomise the solution to a very fine mist.
* Always be sure your light is off and cool before foliar feeding! For extra safety, wipe your bulb with a dry cloth after spraying and make sure H.I.D lights are raised to a safe distance (double the distance is a good rule of thumb) to prevent burning.
* Make sure the PH of your solution is between 7 and 6.2.
* To prevent the water from beading up (acting as small prisms) and thereby burning the leaves, for each gallon made, add half of a teaspoon of liquid detergent (wetting agent).
* Spray leaf surface -- the tops and the undersides -- until the liquid begins to drip off the leaves. Stop spraying 2 weeks into flowering -- use sparingly on bud sites.
* Dispose of excess spray according to manufactures instructions home made fertilizer sprays will be fine for at least 2 weeks.
* Spray one time a week every week, if any white residue is found, rinse the foliage with plain ph'd water to reduce salt build-up.
Personally, I do not foliar feed in any situations other then those mentioned below, as, IMO, it does not seem to be necessary if using a well-managed hydroponic set-up. The reasons I foliar feed, are mainly to reduce nutritional stress situations. I avoid spraying bud sites, as nitrate salts (the "n" in NPK) are very unhealthy to smoke, fish emulsion smells, and Bat guano could be highly unsanitary so stick to hygenic solutions.
Benefits of foliar spraying:
* To provide a quick nutrient fix for root-zone nutrient problems or deficiencies; this allows more time to solve the problem(s).
* To prevent excess yellowing on clones.
* To instantly provide nutrients via the leaves, which reduces stress on the suffering plant.
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