It isn't getting enough water. Most of the time, if your plant's leaves turn yellow, it's a sign that you're either underwatering or overwatering it. Plants need water to survive, and if they're not getting enough of it, they'll drop leaves in order to conserve their supply.
Poor drainage or improper watering
Water issues — either too much or too little — are the leading reason behind yellow leaves. In overly wet soil, roots can't breathe. They suffocate, shut down and stop delivering the water and nutrients plants need. Underwatering, or drought, has a similar effect.
Yellowing leaves: Usually accompanied by new growth falling, yellow leaves are an indication of overwatering. However, yellow, curling lower leaves can also be an indication of underwatering. Check the soil for moisture to decide which it may be.
Plants exhibit several vital signs when they're getting too much light. The most obvious indicator is leaf burning. This typically causes yellow leaves at the top of the plant directly under the grow lights. While the inside veins stay green, the leaves take on a yellow, burnt look.
Nitrogen deficiency causes a more general yellowing or reddening, initially usually of the older leaves, often accompanied by a lack of vigour. With potassium deficiency the yellowing is often more pronounced at the leaf edges.
When you see an entirely yellow leaf, you should remove it from your plant using a sterile cutting tool. Removing the leaf will let the plant focus its nutrients on healthy leaves. A yellow leaf has lost its chlorophyll (pigment) and it can't turn green again even after you correct the problem.
Irregular yellowing with potential leaf deformities is usually caused either by a pest or a mineral deficiency. If no pests are visible, then this is likely caused by a mineral deficiency, usually calcium or boron. The solution = fertilize once a month, or repot your plant to provide fresh potting soil.
Symptoms of excess sunlight on indoor plants
Strong sun and heat cause the breakdown of chlorophyll in the leaf. Damage appears as pale, bleached or faded areas. These areas eventually become brown and brittle. Symptoms are more severe when strong sun is combined with dry soil conditions.
Telltale Signs of Too Much Light
The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.
If a plant is overwatered, it will likely develop yellow or brown limp, droopy leaves as opposed to dry, crispy leaves (which are a sign of too little water). Wilting leaves combined with wet soil usually mean that root rot has set in and the roots can no longer absorb water.
When a plant is first becoming overwatered, leaves turn yellow. If soil doesn't have a chance to dry out before you water again, leaves start to wilt. When overwatering is the problem, wilted leaves are soft and limp. (If too little water is the issue, wilted leaves are dry and crispy.)
How Long for Plants to Recover from Overwatering? Depending on the circumstances and severity of over-watering your roots may need more time for recovery than others! The good news is that most plants will bounce back between 7-14 days if they're given proper care (which includes rehydration).
When plants have too little water, leaves turn brown and wilt. This also occurs when plants have too much water. The biggest difference between the two is that too little water will result in your plant's leaves feeling dry and crispy to the touch while too much water results in soft and limp leaves.
The only symptom of light burn or light stress is turning green leaves into yellow from the top. It only happens to those leaves that are under the grow lights.
Excess water reduces oxygen in the soil, which damages fine roots and renders the plant unable to take up water. Plants exposed to excess moisture show the same symptoms as plants with root rots, crown rots (crown rot from overwatering) or drought stress.
Light burn causes DNA damage that bleaches a crop's leaves, permanently turning them white or yellow. It also causes damage to secondary metabolites like antioxidants and terpenes, leaving a crop susceptible to diseases while hurting the quality and quantity of its yield.
If you overwatered, but there are no signs of succulent plant leaves falling off or rotting, take the plant out of its container, and the problem is solved. Period. Ensure you leave the soil and root ball intact.
Leaf tips turn brown when that lost water can't be replaced for some reason. Ideally, water flows from plant roots through stems and waterways until it finally reaches leaf tips last. But when water's limited, other plant parts get served first; tip cells lose out and die from a kind of drought.
Not Enough Light
The opposite problem from sunburn, yellow leaves can also indicate a lack of sunlight. In the event of too little light, plants will react on a cellular level to conserve energy and this leads to discoloration of the leaves.
The yellowing of plant leaves is simply due to a nitrogen (N) shortage which is a perfectly natural phenomenon as the plants nears the end of its life cycle. You are in the eighth week of flower, so you are likely close to harvest time depending on your strain.
Most of the time, if your plant's leaves turn yellow, it's a sign that you're either underwatering or overwatering it. Plants need water to survive, and if they're not getting enough of it, they'll drop leaves in order to conserve their supply.
The most common cause for yellowing leaves on trees is a lack of micronutrients—the mineral elements essential for the growth of plants. Micronutrients include iron, manganese, zinc, copper, boron, silicon, and molybdenum.