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One of the best ways to identify any health issues with your cannabis plants are by the leaves. In fact, most all problems with your plants will be first noticeable in the leaves.
For example, if the leaves of your plants are touching the ground, it may be an indicator that they are not getting enough water. When plants are not getting enough nutrients it will be obvious by the color of the leaves.
Yellow leaves generally indicate that the plants are nutrient deficient.
Keeping an eye on the condition of plant leaves is crucial to growing cannabis. Likewise, knowing what to look for will help tremendously in the health of your plants.
Wilting & Limp Leaves
Generally, when the leaves of a cannabis plant are drooping or limp it means that they are not getting enough water. One of the first things you want to check is the soil.
Secondly, the type of soil can play a big factor on how it holds moisture. For instance, soil made mostly of sand will not retain water.
On the other hand, clay soil holds too much moisture and often waterlogs a plant. The proper soil will offer good drainage but hold in the correct moisture for your plants.
Many expert growers agree that the ideal soil mixture for marijuana is 2 parts potting soil (without fertilizer), 1 part organic compost (manure), and 1 part perlite.
Watering – Underwatering & Overwatering
Two of the most typical issues with new growers is overwatering and underwatering. Fortunately, it is an easy problem to fix and identify.
- Underwatered- the leaves tend to droop and growth begins to slow down. The leaves of super underwatered plants will turn dry and crispy.
- Overwatered- the leaves curl downwards and appear to be stiff and unyielding. This is because they are full of water.
To test the soil for moisture, place a finger into the soil to see how wet or dry it is. If the soil is not damp, then the plants need water.
If the soil is extra wet, then the plant most likely is being overwatered. Keep testing the soil with your finger until you get an idea of how often to water your plants.
Hard & Soft Water
Both hard and soft water can play havoc on your plants health. Soft water can actually cause your plants to become dehydrated.
This is due to salt accumulation in the soil. Hard water generally has a high mineral content such as calcium, magnesium, sulfate, bicarbonates.
Some hard water is actually good for your plants, depending on the mineral that is present. It is highly recommended that you have your water tested to know precise chemical composition.
The Importance of pH Balance
Using the wrong nutrient pH for cannabis can be vital. In fact, the wrong pH range is a common issue with many first time growers.
Most growers agree that the nutrient solution for cannabis should be:
Nitrogen – Minimum pH 5.5; Maximum pH 7.5+
Calcium -Minimum pH6.5; Maximum pH 7.5+
Potassium – Minimum pH 5.4; Maximum pH 7.5+
Phosphorus – Minimum pH 6.2; Maximum pH 7.2
Magnesium – Minimum pH 5.8; Maximum pH 7.2
Sulfur – Minimum pH 5.4; Maximum pH 7.5+
Zinc – Minimum pH -5.0; Maximum pH 7.1
The soils pH is also important. For your plant to flourish, the soils pH should be between 6 and 6.8.
Yellow Leaves or Discoloration
Yellow leaves or discoloration is an indicator that your plants are suffering from a nutrient issue. To start, make sure that you are not overwatering or underwatering.
If that is not the case, then check the following –
- Oldest growth or lower leaves fall off- nitrogen deficiency
- The top leaves turn yellowish green – zinc deficiency
- Top inner inside leaves are yellow or white – iron deficiency
- Lower leaves turn yellow at base then spread to tips – sulfur deficiency
- Yellow or brown tips –nutrient burn or high concentrations of nutrients
- Yellowing and dark spots on leaves that fall off – phosphorous deficiency
- Stems are yellowish with brown spots and feel hollow – calcium deficiency
- Yellow along smaller veins with yellow and brown edges – potassium deficiency
- Leaves turn yellow with brown spots between the veins – magnesium deficiency
- Oldest growth or lower leaves turn yellow in-between the veins – magnesium deficiency
- New growth is thick and appears odd with brown spots and yellowing – boron deficiency
It is highly recommended that you keep a log book since so many of the systems are alike. In addition, having the soils pH tested will give you an idea of what nutrients your plants are absorbing.
Once you know the soils pH, you can easily modify the soil to fit the needs of your plants.
Cannabis Leaves are Curled
When cannabis leaves are curled downward, it generally means that the plants are being overwatered. However, when the leaves are curled up, your plants may be suffering from heat stress.
Likewise, leaves that curl away from the plant can have windburn. Plants that are wind burned are typically too close to a fan.
Nitrogen toxicity can also cause leaves to curl downwards. In addition, there will be dark green discolorations in the tips of the leaves.
Nitrogen toxicity can actually kill your plants. Test your soil if you suspect nitrogen toxicity.
Low Humidity
Sometimes the health of cannabis plants can be affected by humidity. Ideally, weed likes a mildly humid environment.
The humidity offers water absorption for healthy growth of the whole plant including the stems, leaves, and bud.
For younger plants, the perfect humidity is at 70%. This humidity level supports the ideal water absorption without the young plant relying on its immature root system.
If the humidity is too low, your plants growth can be stunted because of the stomata shutting down. On the contrary, if the humidity is too high, your plants will absorb less water from their roots and absorb less nutrients from the soil.
Once your plants are finished with their early growth spurts, the humidity needs to be reduced by 5%. Likewise, during the budding stage, optimum humidity is at 40%.
Other Consideration
There are various reasons why the leaves of your cannabis plants are drooping or falling off. Here are a few other reasons for unhealthy leaves
- Light burn
- Heat stress
- Nutrient burn
- Fungus like powdery mildew
- Bud rot from high humidity
- Stress from pruning weed plants
- Humidity and temperature stress
- Bugs such as aphids or spider mites
- Cannabis light stress; dark cycle interruption
Final Thoughts
Growing cannabis is not always an easy job, especially when trying to recognize health issues. Knowing what common signs to look for can be critical when it comes to successful growing.
Recognizing certain signs such as leaves turning yellow or falling off, is a big step to having healthy plants. In fact, it is more than half the battle to having healthy plants and higher yields.            Â