It’s week 8, my buds are flushing. I finished foliar feeding just over a week ago, and I have been spraying the buds with pH’ed water to help them absorb any residual fertilizer left on the surface. I am looking closely at the trichome structure… and at the base of one of the smaller plants, I notice that the buds at the bottom, in the shade,are really frosty, not just regular frosty, clumpy and patchy frosty… That means only one thing… Powdery Mildew!!!

They [spores] need the proper conditions to germinate: a surface that contains nutrients on which they can grow, temperatures over 60?F (16-20 C), high humidity and a slightly acidic environment. Once the spore senses these conditions , it germinates, sending out a hyhae which seeks out a stomata. It enters the tissue and lives off its nutrients, eventually killing the tissue. The downy mildew powder you see on the leaf is the reproductive organ of the plant, which is releasing spores into the air.
-Ask Ed

Powdery Mildew is an airborne fungus, that basically occurs everywhere with friendly conditions. It has been a pain in the ass for commercial farmers since as long as people remember. If allowed to reproduce on your buds, they will spread to any and every surface. And when smoked, powdery mildew creates any of a number of unpleasant side effects including: sniffles, runny nose, itchy eyes, coughing and sneezing, and can trigger asthma and other allergic responses.

It spreads quickly in high humidity, and in the shade, so the best solution is prevention.
Keep your humidity on the low side 35%-45%.
Turn your plants twice a week to keep any one spot from staying in the shade.
Spray fungicides preventatively through the first 5 weeks.

Many commercial sprays are available that prevent powder mildew. Make sure to use an organic fungicide since you don’t want to smoke any harmful chemicals. I recommend either Seranade or Neem Oil. Both are organic, and can be found at most nursery’s.

However, as I said earlier, I am in week 8, so it’s too late to spray chemicals. There is a natural solution. Fungii only survive within a specific pH range. Farmers used to use baking soda, and laundry deturgent to spray for powder mildew, but that sounds dangerous and a little gross. An even easier cure is mixing up a solution of 1 part milk to 9 parts water, and spray directly on problem areas. The lactic acid will kill the fungus. Powdery Mildew has a 3-5 day life cycle, so it is important to spray again 2-3 days later to kill any new offspring.

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.

Foliar feeding is feeding your plants through their leaves. I think the best way to explain it is by first explaining the leaf itself. Warning, for those interested in growing weed, and not so much the science of it, here is the article on foliar feeding. Here’s a diagram:

• The Cuticle is the waxy protective layer on the top side of the leaf, it helps the plant retain water.
• Next comes the Upper Epidermis (botany: Adaxial Epidermis) this is made up of clear epidermal cells only a single cell layer thick. These cells are jammed side by side to offer protection from the outside world. Epidermal cells contain one of the precursors (cutin) for the cuticle. The Epidermal cells are also responsible for my personal part of the plant, the epidermal hairs aka trichomes.
• Under the Epidermis lie the Palisade Mesophyll cells. These are large cylindrical green cells. These contain the chloroplasts, they absorb sunlight, and turn it into sugar.
• The Spongy Mesophyll is a bunch of funny shaped loosely packed cells used for gas exchange.
• The Veins are contained within the mesophyll layer. The Bundle Sheath cells create passageways throughout the plant. Xylem is water containing nutrients brought up from the roots to the leaves. Phloem is the sap containing all the sugars made by photosynthesis which the leaf sends back to
• The Lower Epidermis (botany: Abaxial Epidermis) contains 2 different types of cells, stomata and guard cells:
• Stoma (plural: stomata) is a pore between a pair of guard cells that allow plants to breathe. Leaves need CO2 (carbon dioxide) for photosynthesis, and create O2 (oxygen) as a byproduct. Since the inside of a plant is mostly composed of water, in order to ‘inhale’ CO2, it has to displace (‘exhale’) water vapor from within the leaf, this is called transpiration.
• Guard Cells are bean shaped cells that control the stomata. They contain chloroplasts, so they manufacture sugars, their job is to sense how much water is being released by the plant, and close the stomata to stop transpiration. This is a really complicated process, for more information here’s Wikipedia, scroll down to ‘opening and closure’.
• On the bottom is a another, thinner, cuticle layer.

So, now that we THOROUGHLY understand the leaf, lets explore methods of feeding our plant through the leaves.

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 into a healthy plant, feeding through the leaves is fast and effective.

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