Foliar feeding is a a great way to supplement your feeding. Whether to correct a nutrient imbalance, get the plants eating through nutrient lockout at the roots, or just to get a little more food in there to boost your buds, feeding cannabis through the leaves is fast and effective.

BE CAREFUL: Start with lower than recommended dosages, it is really easy to burn your plants.

Conventional wisdom tells us that plants can absorb moisture through the stomata on the underside of the leaves, so small doses of nutrients can be diluted in water and sprayed on the underside of the leaf, where the plant (or weed) can absorb and use them directly where they are needed.

Now, since we are playing with more interesting things than conventional wisdom, I recommend a product called Penetrator by Dutchmaster.

Traditionally the only holes in the waxy cuticle are the stomata on the underside of the leaf, however what Penetrator does is create a series of tubes coming in through the cuticle into the mesophyll layer. These tubes are lined with water, and evaporate away when the feeding is over It also contains a chemical agent that helps maintain the stability of the reaction. With traditional foliar feeding, the leaf can only uptake nutrients until it runs out of electrical charge, then it begins to close up and reject whatever is left. With Penetrator leaves are able to uptake more nutrients through both sides of the leaf, and they receive more nutrients at each site.

Since foliar feeding is topical, it allows the plant access to the nutrients it needs, at the location it needs them. It allows the plant to recover from any kind of deficiency quickly with minimal energy loss.

Foliar sprays should be alternated, to help the plant thoroughly ingest every feeding. I recommend foliar feeding 2-3 times a week during weeks 2-6 of flowering. I use concentrations of about 400-700ppm of about half nutrient/half Penetrator. Start at the low end, or even a little lower. Always use pH neutral water, whatever the pH of your medium is, 5.6-6.0 for hydro, and 6.0-6.3 soil. Since Penetrator allows your plant to absorb more food, use lower than recommended doses until your plants adjust to foliar feeding.

Products I use to foliar feed:

B-52 – B-vitamins and Norwegian Sea Kelp extract make this a great source of trace minerals. Also B-52 helps you plants be more tolerant to heat and drought. There are two essential plant hormones, auxins and cytokinins. Auxins encourage apical dominance, telling your plant to shoot straight up from the tallest point. Cytokinins do just the opposite, they signal the plant to stop elongating, and to start bushing, and noding closer together. Norwegian Sea Kelp is rich in cytokinins, so wait until you are satisfied with your plant’s height before you spray this one. Start around 200ppm B-52 200ppm Penetrator, and work your way up.

Revive – Advanced Nutrients gift to frustrated cannabis growers everywhere. It is a special blend of super chelated micro-nutrients. If for any reason your plants start to yellow, add 200ppm of Revive to the reservoir, and mix up 100ppm Revive 200ppm Penetrator in a foliar spray. You will see your plants returning to green in less than an hour. This stuff is amazing, and it works before your eyes. (In a pinch, substitute Ca-Mg+, same idea just not as immediately effective)

Humic/Fulvic acid – These are the decomposing remains of peat bogs, refined from leonardite (WARNING: exposure to bare skin may cause skin and eye irritation, handle with gloves). They contain loosely bonded elemental remains that your plant uses to break down its food. Humic acid helps with the breaking down of trace elements, where as Fulvic helps with the breakdown of sugar. Foliar feeding of these basically chemically induces hunger. These natural acids create a demand for nutrients wherever applied, so when applied in small doses directly to the flower, it tells the plant to send more food to the buds. Foliar application also helps your plants get through nutrient lockout at the roots. These two can be combined when added, but start off light, its way easy to burn your buds.

Note: I discontinued foliar feeding at the beginning of week 7, and began spraying pH 6 water on the leaves to help them intake the rest of their food. About 3 days later I found the beginning signs of powdery mildew. It is too late to spray fungicide, so I have to attack the mildew itself. I turned the air conditioner up to impede growth, and dry out the air. Anywhere that is already infected with powdery mildew (in the shade, near the bottom) it can be cured with a foliar spray of 1pt whole milk to 9pts water. The lactic acid will eat the powder mildew alive.

This past week has been a mess. I have been running all over the state helping a couple of friends get started. Unfortunately, in my absence, we developed a bit of a mold (fungal?) infestation. All of us were out of town over the weekend, and when we got back our plants were looking a little more yellow than usual. Upon further investigation, the pH and ppm had skyrocketed! When I first saw something slightly furry growing on the circulation pump, I asked a friend who told me not to worry, it was just nutrient residue… He was wrong. The next day when I checked the ppm it had jumped from 1800 (1200 food, 600 hard water) to 2400 (…?!). The pH had jumped tremendously as well from its usual 5.5-6 up to 7.5-8 (using the liquid test kit this is the max range on the bottle… could’ve been higher). It was in the middle of feeding, and with the res level low I could see the pump completely covered in white fuzz. In a knee jerk reaction, i grabbed a bottle of lemon juice, an began to pour it onto the pump. To my amazement, lemon juice killed it on contact, and washed it away clean. This when I realized I was definitely growing something unwelcome.

We originally believed the source of the problem was the clear reservoir. We cleaned everything out with soap, tap water (yum…chlorinated), and an entire bottle of 3% hydrogen peroxide. Hydrogen peroxide is used as an antiseptic, it is H202, basically really unstable water, when exposed to air and water, the Oxygen shoots off leaving behind water. How does this kill germs? Imagine feeding rice to a pigeon… it goes in, then pop! (sorry if the metaphor was a little grim, I got nothing against pigeons, really, I just get frustrated when my plants are aren’t healthy)

Once exposed to the peroxide, the white stuff would turn brown and dead, and wash away easily. After we had scrubbed everything as clean as we could, it took abut an hour, we put it all back together, added food and 1.5tsp hydrogen peroxide per gallon, and crossed our fingers.

Two days later… back to ground zero. pH-8 ppm-2500 white chunky stuff floating in my reservoir. I pH the water back with lemon juice, and vinegar. This time it takes a ridiculous amount of acid to return to a safe range (I didn’t measure, but I would say about 5x as much as usual). The next morning we took a trip down to The Home Depot, we figured that since the bottom tub was infected, and the top tub wasn’t, we figured the pathogen was probably really enjoying our 600w sun, and decided to switch to a black reservoir.

Once again, we removed the entire reservoir (pumps, tubes, air stones, et al.), soaked it with dish soap, tap water, and a whole bottle of 3% hydrogen peroxide, and scrubbed till our hearts were content, then threw away the clear plastic Petri dish.

With the black reservoir in place, and armed with our new friend hydrogen peroxide, and a couple of fresh lemons, we mixed up a new batch of water for the girls. They got mostly sugar and B vitamins to help them recover, and I took off to hunt down some Revive from Advance Nutrients. I picked up some Revive for a friend, and got to see it in action. He had had a tough week, he underfed his plants, then overcompensated, burned them, and created nutrient lockout. He was flushing when I got there, we added a couple hundred ppm of revive to the water, and mixed up a foliar spray for the particularly sad girls. Over the next half hour we watched as all of the yellow leaves began to return to green. Of course when I need some, its not that easy, the stores around me don’t carry it… I end up adventuring far and wide, and just gave up and crashed at a buddy’s pad.

Two days later… Its Back!!!! Finally, it’s time to consult a professional. It’s been almost a week now, and my girls are still yellow. I took a trip down to the hydro store, I described my symptoms, and how I had attempted to solve it… They were about stumped too. None of the guys there had ever seen a mold matching my description. The roots have no signs of rot or decay, its not spreading into the grow medium, it only lives in my reservoir, it makes my water super alkaline, and it won’t go away!!! Since we are in flower, using a chemical fungicide is out of the question, so the only recommendation they had was to kick it up to some industrial strength H202. Mad Farmer’s Oxygenator is a 35% aqueous hydrogen peroxide solution.

So this time we disassembled the reservoir, took everything into the shower, and poured in half a bottle of bleach and a gallon of water, scrubbed everything, and let it soak for half an hour. When you rinse it out make sure you do so thoroughly, take it into the shower, and rinse it way longer than you think you should… bleach kills living things. Once we put it all back together, I mixed up some fresh water with 1.25tsp/gal of the Oxygenator, and got the pH to 5.6 squeezing in a fresh lemon (note-possible source of contamination: unrefrigerated lemon juice can grow bacteria). Oxygenator is the business, we gave them a short 15min feeding with the water peroxide solution to clean out the root zone (just in case). I took a peak into the top table while they were feeding, and it looked like club soda, every surface was covered in tiny scrubbing bubbles, and the water was remarkably clear. I wish I could post a picture, but it wouldn’t come out.

Hydrogen Peroxide is great for killing bacteria, however it kills beneficial bacteria as well, not just the bad ones. However beneficial bacteria probably would have stopped it from taking hold in the first place. We just bought a reverse osmosis unit from ebay this week. I’ll post an article on setup, and that will open the door to a series on the benefits of using bacteria offensively

Also if we the plants were still vegetating, we could have used a mild dose of commercial fungicide. I have had good results with Physan 20. It is a disinfectant, fungicide, virucide, and algaecide, so the only living thing is the plant. Be careful, too much of this stuff will kill everything! I recommend 1tsp/gal or less, and reapply if necessary.