Marijuana leaves with yellow spots are a common occurrence, that much is clear to us. Now it's time to find out why: do all yellow marijuana leaves have the same cause? Absolutely not. There are multiple factors that cause these spots, there are even specific pests that cause yellow spots on the leaves (Septoria). Maybe you are getting overwhelmed, but let's go step by step to find out why you have a yellow plant.
What is clear is that before discovering the remedy, we have to find the correct diagnosis. And since we are going to touch on different causes, we are going to go from the general (which is usually the most common) to the specific. Let's start taking care of your marijuana plants.
Yellow marijuana leaves, have you checked the pH?
As basic and obvious as it may seem to maintain a proper pH in our plants, let's not rule out this factor as the culprit of yellow marijuana leaves. If this is your problem, the yellowish color may be accompanied by a shade that is closer to brown. In addition, it is also common for the ends of the leaf to burn.
You probably already know this, but it is worth remembering: If we are talking about hydro and coco, the pH level should be between 5.5 and 6.5; while, if your crop is in soil, the pH should be close to 7 and certainly not go below 6 in any case.
But what happens if we go too far? The symptom also causes marijuana leaves with yellow spots, but in this case they manifest themselves in the form of a streak.
Flowering marijuana plant with yellow leaves, too much watering?
We continue to analyze the possible faults that can cause a flowering marijuana plant with yellow leaves. In this case, we simplify the problem (in case the error is in the watering), since only an excess of water causes marijuana leaves with yellow spots. Yes, a lack of watering can also be fatal, but it has other consequences.
To rule out this fault, you have two options: either you use a moisture meter... or the old-fashioned way... No kidding, this method is also effective! Lift the pots continuously and you will know without any cheating thanks to the weight when you have to give your crop a soaking.
Yellow houseplants, watch out for the light!
Strange that the subject of light hasn't come up yet. Yes, it is possible that poor lighting is responsible for your yellow houseplants. And again, in this case it can be either too much or too little light.
But rest assured that in this case you have it easy: if you see that the yellow marijuana leaves are concentrated at the top and have been spreading from that area, probably your houseplants have the light bulb closer than they should.
Yellow leaves on marijuana start at the bottom of the plant and spread upwards? Well, the problem is just the opposite: you need to give that plant more light.
It seems very simple and obvious, but the solution to this problem is not so simple. Many times, these leaves (especially those that have been burned) cannot be easily removed, so it is better to be safe than sorry. And if you want to avoid at all costs pot leaves with yellow spots, there is nothing like placing a glass to protect your plant from the light.
Yellow marijuana leaves due to temperature
If we talk about light we have to talk about temperature. And it is that many yellowing crops are due to both factors. The good thing is that noticing this problem could not be easier. Touch the leaf for half a minute, and if the heat is bothering you, you can be sure that your plant is also suffering from it.
But having yellow marijuana leaves because of the temperature may also have nothing to do with the light factor. Heat waves are the best friends of yellow weed. Avoid at all costs to never exceed 26-28ºC, because in addition to the specific problem we are talking about, the bud will lose density and will end up dry.
Be careful not to overdo it by lowering the degrees. Anything below 10ºC will cause spots on the leaves of the plants.
Yellow plague on marijuana plants
How strange that we have been talking about problems in our cannabis plants for a while and the word pest has not yet come up. Yes, there are pests that change the color of the leaves of our crop, and we are not only talking about a yellow pest. There are also fungi that make our plants turn brown or even black.
But let's focus. We are here to talk about yellow leaves in marijuana, and this is synonymous with focusing on a specific pest: have you ever heard the word septoria?
Septoria, the yellow pest on marijuana plants
The concepts Septoriosis and yellow pest on marijuana plants are synonymous. Also known as yellow leaf spot, this disease not only gives a yellowish color to our leaves, but can even destroy them, limiting their size or even stopping them in their tracks.
Specifically, it is the Lycopersici and Septoria fungi that cause yellow and brown spots on our plants. Yes, we are talking about marijuana, but this pest is a threat to different types of crops.
This fungal threat appears when the flowering phase begins. And as we have mentioned in the case of the lack of light, it appears at the base from where it moves to the top of our plants. In addition, the color evolution goes practically always from yellow to brown.
How to fight Septoria
As you are about to discover, there is no magic formula to fight this fungicidal threat, but it does not hurt to remember a series of actions that will help you both eliminate and prevent Septoria:
- Remove infected leaves only if they have not expanded to the middle and top of the plant.
- Subtract humidity from your growing area, even if you have had it under control, it is a good idea to reduce the percentage once you have detected this problem.
- Pull any surrounding weeds. No matter how small and insignificant it may be the cause of your marijuana leaves with yellow spots.
- Change the growing position of your plants from one year to another. It is possible that the crop is finished, but the fungi may have the site saved.
- The best prevention is to follow all the advice we have given you in the post from the very beginning. It sounds cliché, but prevention is better than cure.