What Is Overfeeding and How to Fix It

Nutrient burn can happen in any stage of growth, it’s essential to avoid overfeeding if you want a successful harvest.
01 April 2021
8 min read
What Is Overfeeding and How to Fix It

Contents:
  • 1. What is overfeeding?
  • 2. Nutrient burn causes
  • 2. a. Drying out the soil too much
  • 2. b. Overusing bloom-boosters
  • 2. c. Mixing nutrients too strong
  • 3. Signs of overfed plants
  • 3. a. Nutrient burn during the vegetative stage
  • 3. b. Nutrient burn during flowering
  • 3. c. Nutrient burn vs nutrient deficiency
  • 4. How to fix nutrient burn
  • 5. How to prevent overfeeding
  • 6. In conclusion

Nutrient burn is the result of overfeeding and it’s a super common mistake among new growers. Unlike humans, plants do not get fatter and bigger with more “food”. If you give nutrients in excess, your plants will start to show signs of stress.

1. What is overfeeding?

Nutrient burn is the result of overfeeding. When feeding in excess, your plants will start to show signs of stress like the tip of the leaves yellowing and ultimately, browning and dying of the leaves. To avoid this it's essential you follow the schedule the manufacturer provides and adjust accordingly.

A TDS meter measures the amount of nutrients in a solution (PPM), this is the only way to know exactly how much nutrients you're giving your plants and is the best way to avoid nutrient burn.

 

Stages of growthPPM (Particles per million)
Seedlings100 - 250
First half of vegging300 - 400
Second half of vegging450 - 700
First half of flowering750 - 950
Second half of flowering1000 - 1600
End of flowering and harvest0

Appropriate PPM for each stage of cannabis growth.
 

Nutrient burn is the result of overfeeding and is something that all growers have dealt with because some plants need more nutrients than others, nutrient burn or deficiency can happen to more experienced growers but it’s more common with new growers.

 

What Is Overfeeding: excess of nutrients

If you want to avoid nute burn it is better to start with a low dose of nutrients and gradually increase it.
 

Just like humans, plants start “eating” a small amount of nutrients and will start to need more as they grow, that’s why manufacturers usually provide a feeding schedule, even though the dosage they recommend can vary from strain to strain and on the medium you’re growing in, it’s a good guideline. 

So if you're wondering what to feed marijuana? You should have in mind that all cannabis feeding provides the same nutrients which are Nitrogen, Phosphorus, and Potassium, although the amounts may vary according to the medium, environment and specific strain so make sure you look at the signs your plants give you when feeding weed.

If you want to provide an optimal amount of nutrients you can use a TDS meter, measuring the PPM (particle per million) will guarantee a healthy plant.

2. Nutrient burn causes

As the name says, the cause of overfeeding is the excess of nutrients and this can happen in a lot of ways:

Drying out the soil too much

When the soil is drying out your plant will have less water while the nutrients remain the same, this will cause a sudden increase in the nutrient to water ratio and can affect your plants.

Overusing bloom-boosters

Bloom-boosters aren’t anything else than Potassium (P) and Phosphorus (K), even though they can help you get a better harvest, using too much will cause nute burn.

Mixing nutrients too strong

A too-strong nutrient solution can affect plants in all stages of growth but younger plants with less developed roots can have a hard time recovering from nute burn.

Overfeeding can happen with organic and synthetic nutrients but because organic feeding makes the nutrients available in the medium and synthetic nutrients feed the roots directly, it’s more common with bottled nutrients.

3. Signs of overfed plants

When the roots absorb more cannabis nutrients than the plant can use, the excess will inhibit water from being transferred throughout the plant and this is when you’ll start to see some signs of overfeeding.

 

What Is Overfeeding: signs of nute burn

The leaves will start to yellow and become crispy in more serious cases of nute burn.
 

You should be really careful when mixing the nutrient solution that you're giving your plants, because plants don’t have a way to deal with an excess of nutrients, they will start to show signs of “nute burn” like:

  • Bending of the tips
  • Yellowing or browning of the leaves
  • Leaves with crispy tips
  • Leaves twisting

Nutrient burn during the vegetative stage

In can be easier to deal with nute burn in the vegetative stage because there are no buds to be affected, so you will only suffer from a couple of burnt leaves if you can control it in the early stages.

Even though it's easier to deal with because you're not risking your buds, have in mind that depending on the amount of nutrients you've given to your plant, all the leaves can ultimately burn and it can be really hard for your plant to recover.

Nutrient burn during flowering

Buds can also be affected by nutrient burn, when changing from vegetative to flowering nutrients, cannabis needs a higher amount of Calcium and Magnesium to produce flowers properly. 

 

What Is Overfeeding: signs of nute burn during flowering

Nute burn can also happen during flowering and in more extreme cases the buds will burn and rot.
 

Depending on the medium, you will have to provide those micronutrients, and can be easy to burn your plants if given in excess, remember nutrient burn can be caused by macro and micronutrients even if they are used in lower quantities.

If you overfeed during the flowering stage, the symptoms will be the same but it can be riskier because if the buds brown, they can die and start rotting, ruining your harvest.

 

Early symptomsAdvanced symptoms
Slow plant growth cause by nutrient lockBrown spots on leaves
Leaves curl downwardsBurnt tips of leaves
Leaves edges burntLower leaves damaged (macronutrient excess) or Top leaves damaged (micronutrients)
Yellowing on the tip of leavesLeaves dying and falling

Nutrient burn vs nutrient deficiency

When identifying symptoms it’s crucial you don’t get confused because the symptoms of overfeeding are similar to what plants show with other problems like plant heat stress symptoms or light stress, potassium deficiency, nitrogen deficiency (or other nutrient deficiencies) or pH oscillation. 

 

What Is Overfeeding: signs of nute burn

Nute burn symptoms can be similar to nutrient deficiencies symptoms so make sure you don't get confused.
 

Nitrogen and potassium deficiency can be easily mistaken for nutrient burn but they happen if there's a lack of nutrients and not an excess, while the symptoms of nitrogen deficiency are the yellowing of the leaves, starting by the tips, the symptoms of a potassium deficiency are yellow and brown spots in the leaves.

Because they're very similar to nutrient burn, it's essential to control the amount of nutrients in your watering solution so if this happens, you know exactly how to deal with it.

4. How to fix nutrient burn

If your plant is showing signs of nutrient burn, first make sure it indeed is an excess of nutrients and if it is, you can easily fix it by following 4 simple steps:

Cut off the affected foliage

If the leaves have already started to brown and die, it’s essential you remove them.

Dying leaves can ultimately rot and this will cause even more problems, like mold and even bud rot, depending on where those leaves are.

Washing the roots and medium

Just like when flushing before harvest, when your plant suffers from overfeeding it is essential you remove the excess nutrients in the medium and in the roots.

 

What Is Overfeeding: 4 steps to deal with nute burn

Four easy steps to deal with nutrient burn.
 

To do this, you need to flush with pH water (5.8-6.3 for soil) 2 times a day, ideally, you would water until you see run-off coming from under the pot and repeat it after 15-30min.

If you want to make sure you're doing it properly, you can measure the PPM of the run-off, this way you'll know when you have washed off the nutrient excess.

Adjust the nutrient solution 

Usually the manufacturers provide a feeding amount and schedule but it can vary according to the medium and strain you’re growing, to keep things safe it is recommended to use a TDS meter but if you want to keep simple you should always start with a smaller dose than what your nutrient solution advises and increase little by little.

Help the roots recover

To help the roots recover you can use root stimulators which contain vitamins, hormones and microbes that will make the roots develop stronger and faster, by adjusting the nutrient solution and helping the roots recover you’ll see your plant coming back to normal in no time.

5. How to prevent overfeeding

When preparing the nutrient solution to water our plants we need to make sure we are giving the right amount of nutrients, if you don’t have an TDS meter, here’s a guide to help you avoid problems without having to buy expensive tools.

 

StagesNutrients
SeedlingWater
First half of the Vegetative stage½  dose of Veg. Nutrients
Second half of the Vegetative stage1 dose of Veg. Nutrients
Pre-flowering stage½ dose Veg. Nutes + ½ dose Flowering Nutes
First half of the Flowering stage½ dose Flowering Nutes
Second half of Flowering Stage1 dose of Flowering Nutrients
Ripening and HarvestFlushing (water)

Amount of nutrients per cannabis plant stage.
 

Because all plants are different, even plants of the same strain, you should always start with ½ or even of the recommended amount, after you see your plants are okay and don’t show stress symptoms, you can slowly start increasing the amount of nutrients.

What should beginners keep in mind to avoid overfeeding?

For more experienced growers, overfeeding shouldn’t be a problem and, but if it’s your first time it can be hard to know what to do so here are a couple of things you should have in mind to prevent overfeeding.

Growing conditions

Every strain is different and may thrive in slightly different conditions so it’s recommended you know what the specific strain needs because the growing conditions affect your plant’s basic processes such as transpiration and photosynthesis.

 

What Is Overfeeding: growing conditions

Remember that the growing conditions also include the substrate which is where the roots grow.
 

If you can’t adjust the growing conditions, make sure the temperature and humidity are in the acceptable range.

Nutrients

You can find organic and mineral nutrients in most grow shops, organic nutrients are derived from natural sources and are usually released slowly because they stay in the substrate, allowing the plant to absorb what it needs.

Mineral nutrients are fed directly to the roots and can be easier to overfeed so make sure you make a wise choice when buying your fertilizer.

pH levels

If the pH is too high or low, your plant will struggle to absorb nutrients, make sure you check and adjust the pH of the nutrient solution. If you don’t have the tools, you can ask for a lab test from your water company, this will allow you to better control what your plants eat, thus avoiding problems.

6. In conclusion

Nutrient burn can be scary if you’re new to cannabis, but luckily, it is quite easy to fix.

We recommend using organic nutrients for cannabis because it’s harder to burn your plants with them, but if you cannot find them where you live, make sure you take a look at our chart to avoid nutrient burn.

If you’re experiencing nutrient burn or still have doubts about it, feel free to leave us a comment below!

01 April 2021
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