You don’t want a nitrogen deficiency in the vegetative stage!
The 3 numbers on the front of plant nutrient bottles list the amount of Nitrogen, Phosphorus, and Potassium.
Problem: A cannabis nitrogen deficiency will cause the older, lower leaves on your plant to turn yellow, wilt away and eventually die. The plant typically appears pale or lime-colored.
Solution: You can find many pre-mixed nutrients from the store which contain nitrogen or you could use nitrate of soda or organic fertilizer which are both good sources of nitrogen. In fact almost all plant nutrients of any kind will include nitrogen. If you haven’t been providing any nutrient to your plants, try supplementing your regular nutrients with a bit more nitrogen and see if the plant starts recovering.
However, if your cannabis plant is losing lower leaves fast due to yellowing (if yellowing and dying leaves is “climbing” up the plant from the bottom), especially in the vegetative stage before plant is making buds, you have a problem that you will need to fix as soon as possible.
Flowering Stage – lower levels of Nitrogen (use “Bloom” or Cactus nutrients)
The first cannabis plant pictured below is showing signs of nitrogen deficiency late in flowering; nitrogen deficiency in late flowering is completely normal and even desired. The last picture is an infographic about nitrogen and your marijuana plant.
Nitrogen-deficient plants often appear pale or lime-colored. The leaves on this marijuana plant don’t have obvious leaf symptoms like spots or markings, but they are pale all over the whole plant. Almost lime green. The light-colored leaves are a sign the plant needs more Nitrogen (and nutrients in general). On the flip side, plants that are receiving too much Nitrogen turn dark.
It is not good if your cannabis plant is showing signs of an advanced nitrogen deificiency while still in the vegetative stage. It’s normal to lose a few yellow leaves off the bottom of your plant here and there, especially with very big plants. But if you are losing a significant amount of yellow leaves, and the yellowing seems to be moving up the plant quickly, then you have a problem.
A nitrogen deficiency causes the lower/older leaves of a cannabis plant to start yellowing, wilting, and dropping off on their own. Learn how to fix it.
Chronic overwatering can sometimes cause unusual deficiencies even if the pH is spot on, like this plant grown in muddy soil. The biggest sign that these symptoms are caused by overwatering and not pH (or something else) is that the plant is always droopy.
Light burn symptoms can be different from plant to plant, but they always seem to happen mostly to the parts of the plant that are closest to the light
Sometimes marijuana leaves turn yellow for totally normal reasons, including….
One of the most common pests that can cause yellowing without really any other symptoms is fungus gnats. These tiny winged creatures hang around your wet topsoil, and are most likely to appear if you’re overwatering your plants. Although the adults don’t attack your plants, their larvae feast on the roots, which can eventually cause yellowing, especially on small or weak plants.
You don’t normally see these in pictures because most growers remove them 🙂
Chronic Underwatering (Relatively Rare)
Note: Adult cannabis plants without enough light won’t grow well either, but they likely won’t have yellow leaves. In fact, adult cannabis plants that are getting relatively low levels of light will actually turn dark green since they aren’t using up nutrients for photosynthesis (the extra unused nutrients get stored in the leaves, causing them to appear darker).
This plant is on the verge of a Nitrogen deficiency. This is indicated by its overall pale color, even though all the leaves look really healthy without any spots or stripes. Cannabis leaves should not be lime green or pale, or the plant tends to grow more slowly!
Are your marijuana leaves turning yellow? View the 10 most common reasons this happens (with pictures) and get the solutions!