Foliar Feeding: Myth or Miracle?
... with a lot of anecdotal support. So we thought we would get to the bottom of it, and weigh in on the craze ourselves.
You know how it is in the cannabis cultivation world: when something is said enough, people tend to believe it. The current illicit nature of cannabis makes it hard for definitive and proven facts to rise to the surface, and many hobby growers have to rely on anecdotal reports when deciding how to properly look after their plants. Foliar feeding is no exception to this. Hop onto any cannabis forum, and there is likely to be a post about how well foliar feeding works. So we want to know, just how effective is it? And is it worth the effort?
FOLIAR FEEDING: HOW IT WORKS
The actual concept of foliar feeding is pretty simple. The great majority of plants, including cannabis, are able absorb water through the stomata in their leaves. So by spraying you cannabis with nutrient rich water, you are able to inject a dose of food directly into the main body of the plant itself – supposedly with almost instantaneous results.
FOLIAR FEEDING YOUR CANNABIS: IS IT WORTH IT?
Whether foliar feeding works is not really in dispute. It is well documented that plants are able to absorb water through their stomata, so there is no reason to think that cannabis wouldn’t. What we really want to know is whether it is significant enough to bother doing it.
From our own experience, we would liken foliar feeding to an enhancing supplement that boosts growth, much in the same way an advanced grower may use addition CO2. It can also be a great way to ensure your cannabis still has access to all the nutrients it needs if your cannabis currently has root stress.
However, a small boost in performance is all you are likely to get. Whilst the effects of foliar feeding can be seen quite quickly, the actual uptake of nutrients is slow, short lasting, and rarely spreads beyond the actual leaf that absorbed it. Also, as a plant ages, it becomes increasingly harder for it to absorb anything through the leaves, due to “leaky” plant cells that fill intercellular space – which is where the ions of the liquid being absorbed travel. (Source: "Mineral Nutrition of Higher Plants, 2nd edition" by Horst Marschner).
Don’t get us wrong, foliar feeding DOES get results, and many growers report bigger plants and bigger yields as a direct result of it – just don’t try using it as the main source of nutrients, you will still need to feed your roots with your main feed in order for your cannabis to get all of the sustenance it needs.
HOW TO FOLIAGE FEED YOUR CANNABIS
If you are interested in giving you cannabis plant a boost, then it is pretty easy to do. Many anecdotal reports will tell you that you need as fine a spray as possible in order for leaves to efficiently uptake the water and nutrients. However, research using radio isotopes to follow nutrients in foliar feed found that nutrients managed to get into leaves just as efficiently when in larger droplets, meaning you don’t have to invest in a high tech, high pressure mister. A handheld water mister/sprayer will do. Ideally you will still want to use a fine mist setting, but this is more for coverage than droplet size.
Simply dilute your selected feed to around 25% usual strength, and give your plant a misting once a day. You can gradually strengthen your feed to 50% and higher, depending on how your cannabis reacts. Just be careful not to overfeed – and remember, you will still be following your regular root feeding schedule, so you will not need too much more.
As a side note, you should only really foliage feed when your cannabis is in its vegetative stage of life. When it begins flowering, it will produce resin around the buds as a protective measure. If you start spraying these, it can fail to be absorbed, causing damp and mould.
So is foliar feeding a miracle? No, but neither is it a myth. It can be a handy and effective boost your cannabis plant’s growth. The fact that it is relatively easy and inexpensive to do also means it is probably worth giving a go. You have little to lose, and as long as you don’t go overboard with the feed strength, or spray your plant when it is flowering, you are unlikely to cause any damage. It is a win-win situation really!