How to Fix Nitrogen Deficiency In Plants

Nitrogen is naturally found in the atmosphere of the earth, enabling all plants to create protein. Nitrogen combines with numerous other minerals enabling plants to complete functions necessary for health and growth.
Nitrogen is commonly found as a nitrate in the soil. Nitrogen is mobile, meaning it can move anywhere in the plant when necessary. Plants require nitrogen to create energy from light and ensure the leaves remain green. Nitrogen is required for all new growth to assist with photosynthesis, resulting in green coloration.
New leaves need the most light, so the plant prioritizes the distribution of nitrogen to new growth. Plants are unable to maintain health without nitrogen because it is vital for several plant processes such as photosynthesis.
Nitrogen is also important for the growth of cells and tissues within the plant and chlorophyll formation. Chlorophyll is necessary for plants to absorb energy from light. Nitrogen helps with protein formation for numerous biochemical reactions. Without nitrogen, plant cells are unable to reproduce and grow.
How Does a Nitrogen Deficiency Affect the Quality of Your Plant?

A nitrogen deficiency in plants results in the older leaves becoming yellow. If left untreated, the leaves will eventually wilt then die. The coloration of the plant becomes a pale lime. A nitrogen deficiency causes browning on the yellowed leaves. In most cases, the leaves will soften, then begin to fold in. If the nitrogen deficiency is severe, the leaves become crispy.
Eventually, the leaves will start falling off. There are often no obvious symptoms on cannabis plants such as markings, spots or yellowing, but the entire plant will turn a lime green color. Plants without nitrogen are unable to process energy from light.
This means the photosynthesis process required for a green coloration is significantly impacted. Only the new leaves will receive nitrogen when the quantity is limited.
If there is not enough nitrogen available to satisfy the requirements of the new leaves, the plant will take nitrogen from the lower, older leaves. Prioritizing the new leaves is what results in the older leaves becoming both wilted and yellowed.
Deficiency Symptoms of Nitrogen in Plants
The symptoms of a nitrogen deficiency in plants include:
- Plants are shorter
- Leaves become a pale yellowish green
- Purple coloration on the undersides of the stems and leaves on tomato plants
- Reduced protein, fruit and flowering
- Stunted growth
- Lateral buds on cannabis plants become dormant

A nitrogen deficiency in plants often results in shorter growth. Although all the leaves can turn a yellowish green, this is much more common on the older foliage.
A nitrogen deficiency on a tomato plant causes the undersides of the stems and leaves to become purple in the impacted areas. The decrease in chlorophyll content of the leaves is what causes chlorosis or pale-yellow coloration.
The older leaves generally become completely yellow. The nitrogen deficiency in plants results in a decrease in starch, protein, fruit and flowering. The loss of protein causes lateral buds to become dormant with plant growth stunted. Plants take on a pale and thin appearance referred to as general starvation.
Possible Confusion with Other Symptoms
- An iron deficiency also causes yellow leaves
- Light burn or stress frequently results in yellow leaves
- Sulfur deficiency results in yellowing leaves
- Zinc deficiency turns the upper leaves yellow
What Causes a Nitrogen Deficiency?
The possible causes include:
- Too much manganese, chloride, zinc or potassium in the soil
- Not enough nitrogen in the soil
- The pH level is too high for the root structure
- Dysfunctional root system
- The nitrogen content in the soil has been washed away
One of the common causes of a nitrate deficiency is too much chloride, manganese, zinc or potassium in the growing medium or soil. If there is not enough nitrogen in the soil, the result is a deficiency. An extremely high pH level, disease, damage and lower soil temperatures can cause the roots of the plant to become dysfunctional. The roots are then unable to absorb nitrogen. Nitrogen can also be washed from the soil.
How to Fix a Nitrogen Deficiency in Plants
A deficiency can be treated by providing plants with a food rich in nitrogen. Local nurseries and garden suppliers offer pre-mixed nutrients containing nitrogen. Organic fertilizer and nitrate of soda are also sources of nitrogen. There is nitrogen in most plant nutrients. Another common issue is a low pH balance. When the pH balance is off, the roots are unable to absorb the necessary nutrients including nitrogen.

Nitrogen can be replaced in the soil by feeding plants in the spring. If the nitrogen deficiency in plants has already advanced, the best option is liquid plant food. This is because this type of food is fast-acting. Fertilizers rich in nitrogen are also recommended. Mulching the soil will help with a nitrogen deficiency by decreasing leaching and maintaining the levels of moisture.
- Treat plants with a food rich in nitrogen
- Use an organic fertilizer or nitrate of soda
- Increase pH for better root absorption of nitrogen
- Increase nutrient levels with regular spring feedings
- Use liquid plant foods
- Mulch the soil
- Use a fertilizer rich in nitrogen
How Long Does It Take for a Plant to Recover from a Nitrogen Deficiency?
Plants with a nitrogen deficiency will absorb the nutrient immediately once it becomes available. The coloration of the plant will improve, turning a healthy green. Severely affected leaves will be unable to recover. The plants should recover in approximately one week.