Back of Your Hand Test – For MH, HPS, CFLs and T5 grow lights (not always effective for LEDs or very high-power HPS lights with strong air conditioning)
Sometimes you don’t see bugs. Thrips are an example of a pest that leaves markings on the leaves which can be mistaken for deficiencies, yet you rarely see the bugs themselves.
With the right tools, the task of maintaining humidity can be close to automated, and you will see huge benefits compared to the amount of time and money you invest.
When it comes to controlling humidity indoors, you may need to use a humidifier and/or a dehumidifier to keep the humidity in the optimal range. A humidifier adds moisture to the air while a dehumidifier takes moisture out.
Second, even if you are providing your plants with the correct amount of nutrients, you still need to monitor and adjust the pH to prevent nutrient deficiencies. How to check & adjust pH for growing cannabis.
Learn how to spot and treat overwatering (with tons of pictures and a comprehensive watering guide)
Make sure your grow space is light-proof! (Unless growing an autoflowering strain)
Step 5: Diagnose Pests (sometimes you never actually see the bugs)
To put that into perspective…
What to do: Use the checklists below to diagnose whether your plant is over-watered, under-watered, or has a root problem.
Similar to spider mites, aphids hang out on the undersides of the fan leaves, but they are green and have long legs almost like a grasshopper. They are pretty tiny as well so I also recommend using the trichome scope for looking at aphids on your leaves. You will see them crawling around and what aphids do is suck the nutrients and water out of your fan leaves, which causes them to wilt and die.
As soon as you spot this issue, raise your lights 6 inches to 1 foot higher. How close your lights should be is always determined by their strength and the stage the plants are in. Be sure to look at the manual your light came with as it will always explain the ideal distances for that specific light.
Underwatering and overwatering are the two most common problems among beginner growers and are also very easy to fix. If you are underwatering a cannabis plant, you will notice the leaves start to droop and they will seem as if they are hanging. Growth will also slow down.
Another issue caused by high humidity and low airflow is bud rot. Overwatering can also cause this to happen, and essentially the results are the rotting of your cannabis buds. It will start from the inside and will slowly turn them brown and moldy until the whole bud is ruined.
Luckily, cannabis plants are extremely resilient and can withstand a harsh environment or an invader for some time. This is convenient because it gives you time to figure out what the issue is and treat it before your plant is completely ruined.
Whenever the tops of your plants are too close to the grow lights above, it will cause the leaves to yellow and burn. The easiest way to spot this problem is to look out for the leaves that are closest to the light; they will begin turning yellow first and then it will spread to other areas to the plant.
The early signs of spider mites includes lots of tiny and light-colored spots on your leaves. It will look like speckles as the dots are so small and close together.