
The easiest way to get potassium into the growing medium at the correct level is to use a balanced nutrients set. Using fertilizers and nutrients put all the required elements into the growing medium, so if you are using a nutrient system designed for cannabis, there is probably plenty of potassium available.
Are the plant's roots healthy?
Root health is critical for the uptake of water and nutrients. If a plant is too big for its container, the plant can become root-bound. When this happens, the roots grow inward and can strangle themselves, slowing the plants nutrient uptake. Other root issues, like root-rot, will also impact the plants nutrient uptake.
Is the pH Balanced?
PH is short for 'potential Hydrogen' but is most often used to describe the acidity or alkalinity of a substance. This is important when growing cannabis because nutrients are not available for uptake by the plant outside fairly narrow pH ranges. Cannabis plants in soil do best between 6 and 7 while cannabis plants in coco or other soilless mediums do best between 5.5 and 6.5.
If the pH is too high or too low, then the nutrients aren't available for the plant to uptake. This is called nutrient lockout because no matter how many nutrients you provide, the plant still can't use them. This is a very common problem for farmers and the best way to combat it is to test the pH at every watering.
How do I correct potassium deficiency?
In most cases, you don't need to worry about a few leaves on the bottom going yellow or getting splotches during vegetative growth. If you are seeing it in new growth during flowering, you should address the problem quickly, since cannabis needs increased amounts of potassium during flowering.
If your plant's roots are healthy and you're using a balanced nutrient solution, you should check the pH of the soil. In most cases, balancing the pH and performing a feeding should prevent further problems.
We recommend Grow, Micro, Bloom from Emerald Harvest since it encourages you tune your mix to get your plants what they need, when they need it.
How do I check the pH?
There are two methods for checking the pH at the plant's roots. The most common method is to water the plant until there is a runoff and then check the pH of the runoff water using a hand-held pH meter. If the pH that comes out is higher or lower than what you put in, then you know that it is unbalanced.
The second method uses a soil pH meter. These unit have probes that allow them to test the soil near the roots after a watering.
How do I balance the pH?
To balance the pH, flush with water until the runoff is in an acceptable range. After the pH near the roots is at the right level, follow up with a hearty dose of nutrients and the problem should be solved.
To correct a deficiency, aim for a pH of around 7 in the soil, or 6.5 in coco, to get the most potassium uptake. If you notice the yellowing continuing, you likely have a root condition. If the pot is too small, transplant into a larger container.