GrumpyGrower's guide to foliar feeding

[seymore_budz]

This is one topic that has been covered a few times online but I can never find one source of information to refer back to so here is my attempt at collating some of the information that seems to be spread out all over the place and pop it into a nice thread to refer back to and to share the knowledge about.

What is foliar feeding?

Everyone knows that plants take up nutrients from their roots and distribute them throughout the leaves but some may not know that plants can also take up nutrients and stimulants applied to the leaves. Not only can they consume both, they can make use of them very fast and efficiently. Nutrients and stimulants are taken up via the leaf stomata and epidermis. This allows the plant to make immediate use of whatever was applied rather than waiting for them to traverse their vascular system. While researching foliar feeding I found lots of differences in opinions and conflicting information about both the application and effectiveness of foliar feeding. Let's explore the art of foliar feeding as well as bust some of the myths on the way.

Foliar feeding allow the plant to make use of the applied nutrients up to 10x faster than feeding via the roots. This makes it an excellent tool for correcting deficiencies in the plant. That includes plants that may be suffering deficiencies due to root damage caused by over/underwatering plants. Foliar feeding plants in these situations can actually save a plant's life! That being said, it can also cause major issues and even kill a plant overnight if not done correctly. Let's explore some best practices!

Spray both sides of your leaves

Although plants can take up goodies from both the stomata and epidermis, it's thought that the majority is taken up by the stomata. Stomata will be present on both sides of the leaf but will be more dense on the underside of the leaf. For that reason, it's considered a best practice to spray the underside of the leaves.

Spray in low stress environments

Following on from above, the stomata also react to environmental conditions and will close if the temperature is above 28C or the humidity is below 40% This is why it's also worth considering the environmental conditions before spraying anything onto the leaves. If you spray the plant when it's hot or suffering from low humidity, uptake will be greatly reduced and you also run the risk of exacerbating issues that already exist in the plant. If you're battling these types of environmental issues, you could take your plant out of the grow room or switch the lights off and try to improve the environment without the high intense lighting. Once the plant has cooled down and the humidity is within acceptable ranges, the leaf will relax and the stomata will open increasing uptake.

Consider your water quality

I know I bang on about it a lot on the forum, but water quality really does matter when applying foliar sprays. Hard water that has a lot of calcium carbonate will leave all that salt behind on the leaves. That's not good for the plant as it stifles the leaf and inhibits the ability for the stomata to work correctly. Please guys, use filtered or distilled water. Your plants will love you for it as will I :D

Spray when the lights are off

This one is one of the most debated topics when it comes to foliar feeding. Previously it was thought that spraying plants in high intensity lighting would burn your leaves due to the water droplets acting as a magnifying glass and burning the leaf. This is in fact true! There was a study recently conducted by a bunch of scientists from Hungry and Germany and their conclusion was spraying in intense lighting conditions would burn the leaves. You should spray just before your lights come on or go off indoors or if growing outdoors, you should spray your plants just before sunrise or sunset. [1]

Use a wetting agent

Wetting agents play two roles in aiding the foliar application. First, wetting agents soften the surface tension of the water, allowing the water droplets to sit flat on the leaves. This improves coverage and in turn, improves uptake. Second, they also make the water "sticky" so it doesn't run off the plant. This also improves uptake as the nutrient rich water stays in contact with the leaf for longer. It's not essential but it will improve the coverage and uptake significantly. Wetting agents also improve pesticides using the same mode of action.

Now we've covered some best practices, let's talk about what to add to our foliar spray. Whether you're spraying to correct an issue or just improve your plants, you'll need something in the water. Let's start with nutrients.

Nutrients and additives

Not all nutrients are equal and some are more easily absorbed than others. This is why I always recommend you use a nutrient formula that has been made to be applied via foliar application. I'm not saying you'll kill your plants using some A & B or some organic tea you've put together but I'm saying that a formulated mix will be taken up by the plant easier and consumed faster. That being said, if you're interested, iron chelate has been used for many years in commercial greenhouses to correct all sorts of uptake issues. You'll often find pre-mixed pesticides contain a little iron chelate to help with the recovery after the plants have been attacked by pests. If you want my recommendation on what base feed to use, I use Formulex by Growth Technology :D Not sponsored or anything but Formulex is a great all round plant fertiliser and makes an excellent foliar blend. Spoiler alert, this won't be the last time Growth Technology is mentioned.

As previously mentioned, plants can also take up stimulants via the leaves. There are many stimulants you can use and it's a very VERY deep subject but there is one all rounder that most gardeners would agree contains a lot of beneficial stimulants that will improve uptake of nutrients, improve resistance to pests, increase photosynthesis and also reduces the effects of environmental stress and that's Ascophyllum nodsum. Ascophyllum nodsum is a cold seawater brown algae that contains a plethora of trace elements, amino acids, polysaccharides, enzymes and protiens that will do all previously mentioned. This is why it's hidden all over the place in products like Atami Alga-C, BioBizz Alg-a-mic and many more. You've probably used it and not even realised. I like to use Nitrozyme as my all in one booster. Nitrozyme is tried and tested, it's cheap and it works great. It's also slightly acidic so it reduces the PH a little. I've included a link at the bottom of this write-up.

Finally, I like to add a bit of fulvic acid. Fulvic acid acts as a chelator, forming ionic bonds with nutrients, making them more accessible to the plant. If you're spraying with organic fertilisers, fulvic acid has the ability to break things down and make it available to the plant.

PH and EC

Ok, we have discussed best practices, and what to put in the water but we still have a little ground to cover. Let's now discuss PH. It's a difficult one, do we PH or not? So foliar feeding is kind of like hydroponics. When growers say don't PH when growing in soil, they are normally saying this because soil will self regulate. Spraying onto the leaves on the other hand doesn't have a buffer so PH is critical in maximising uptake. PH should be treated as if you were feeding hydroponics and be around 5.6. If you're going to drop the PH, I'd recommend phosphoric acid as phosphorus is easily taken up by the plant. If you've used filtered water and formulex, after mixing the above, the PH should be around 6. If this is the case, I wouldn't bother with the PH down. I'd only use acid if the PH was higher than 6.5

If you're using organic feed the EC will be irrelevant but if you're using salt based nutrients like formulex, you're looking for an EC between 0.7-1.0EC. You really have to watch you don't overfeed when applying nutrients via the leaves as it's very easily done and can burn the shit out of your plants real quick. I wouldn't recommend going above 1.0EC

Caveats

With everything, there are a couple of things to consider before jumping balls deep into foliar feeding. Plants can take up and use the nutrients fast but this can also lead to overfed plants if your plants are already well fed or you apply too much. A little really does go a long way when it comes to foliar applications. If you're working to try and correct issues, you can spray once a day until you see improvements, then scale it back to once a week. If you are spraying to boost your already healthy plants, once a week is more than enough.

Do not spray after you see thumb size heads. Although foliar feeding can improve mold resistance, the mode of action is not active and will not kill mold spores. If you're spraying your plants after this time, you are in fact increasing your chances of getting mold by increasing the humidity around the buds.

Conclusion

Thank you for reading my little foliar feeding post. I hope someone learns something from this and more of you try foliar feeding! Foliar applications can be a lifesaver as well as a great addition to your growing regime. It can increase activity in the plants, improve resistance to pests and even mold and give you that edge to produce some of the best cannabis you've ever smoked. I feel a little mean for the GT plugs so I'm going to show some love to the Nutriculture mandem and promote one of their products. And that's called Plant Magic Evolution. Plant Magic Evolution is a foliar spray that contains the majority of beneficial stimulants discussed in this write-up. If you just want to buy something and spray away, that's the product for you. They also sell a wetting agent called Bio Wetter. Bio Wetter is pure yucca and will act as an excellent surfactant.

I've glossed over lots of details and there's loads more out there to discover! Let the community know your experiences. Do you foliar feed? If so, what are you using in your mix?

Take care all !

Citations:

[1] https://www.abc.net.au/science/articles ... 475079.htm

Further reading:

http://www.newagenutrients.com/educatio ... m-nodosum/
https://www.growthtechnology.com/product/nitrozyme/
https://www.growthtechnology.com/product/formulex/
http://www.plant-magic.co.uk/products/bio-wetter/23/ (Yucca extract)

[Thrasherdude]

Very Nice topic Grumpy! I only use foliar in Veg with nutes for quick growing the plants and I also foliar spray with just only tapwater for highering the moist % if necessary.

[Josh]

Awesome write-up bro

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[Nom]

Very useful cheers gg

[seymore_budz]

Thanks for your kind words all. I have more write-ups to come but have to go at a slow pace as I'm always pushed for time. Next one is going to have to be RO part II.

[Josh]

I'll be spraying this up until 2-3 weeks of flower https://dragonfly-earth-medicine.square ... 16?cs=true
More of a preventative to bud rot and pm

I'll be following your recommendations for sure



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[MrNice]

grumpygrower thought you may give us a receipt make some our selfs or you need a lab to do that...?

[seymore_budz]

grumpygrower thought you may give us a receipt make some our selfs or you need a lab to do that...?

Lol you want a recipe? I said what I use in the thread above. Here's what I mix up if I'm going to give them a foliar spray. I mix and match products as I go. Atm I'm using formulex and Nitrozyme.

500ml RO water
2ml Formulex
1ml Nitrozyme | 1ml Alga-C
Vitalink fulvic 5ml | ferro humine-ex 0.5ml

Spray 30mins before the lights come on or if you're 24/0, swich your lights off, wait.15 mins, spray the plants, give them another 30-45mins to dry and switch your lights back on..

[seymore_budz]

I'll be spraying this up until 2-3 weeks of flower https://dragonfly-earth-medicine.square ... 16?cs=true
More of a preventative to bud rot and pm

I'll be following your recommendations for sure



Sent from my LGMP260 using Tapatalk

Awesome, thanks for sharing Josh!! I think I'm going to have to get some of that shizzle for myself, looks awesome stuff! I've used the bacterias from Hydrogarden but they leave a horrible mess and don't contain all the goodies like that Natural Mistik.

Edit: Just saw the price over here!! I'll let you test it before I jump in.... £60 a tub over here!!! I spat tea from my nose when I saw that lol $42 direct. That's some fooking markup.

[Mini-G-Star]

Very interesting Grumpy Grower, I voted no as that's what my mentor reckons