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Nutrient Burn In Cannabis Plants

Nutrient burn can affect cannabis during any stage of growth. Prevention, identification, and remediation are all essential pieces of knowledge in the cannabis grower’s arsenal.

Contents:

NUTRIENT BURN

Nutrient burn in cannabis could be called the “novices lament” or “over-enthusiasm backlash.” Nutrient burn is a type of stress caused by overfeeding your plants or mixing nutrients too strongly. Novice growers are often under the misconception that more is better. This is very untrue. Often, burning can be caused by simple human error. Luckily, the condition can be fixed before it demolishes your crop. That said, it can damage a crop at any stage of its development.

Unlike animals (humans included), plants don’t put on weight when you overfeed them. After all, plants are a whole different order of organism. They require a balanced and ongoing series of chemical reactions to survive and thrive. Trying to fatten them up with extra feeding is the fast track to disappointment.

Nutrient burn can be caused by:

  • Mixing nutrients stronger than recommended during any phase of growth
  • Overwatering; plants need a dry period to function properly and access oxygen
  • Using bloom boosters too often or in too high a concentration
  • Using growth stimulants too regularly, causing dwarfism and burning due to excessive nutrient uptake

IDENTIFICATION

Nitrogen is the predominant compound found in cannabis nutrients, especially during the vegetative phase. Nitrogen toxicity will be quickly followed by more severe symptoms.

Early indications of nutrient build-up prior to burning can be:

  • Very deep green leaves
  • Bright, Day-Glow green, almost fluorescent tips
  • Leaf tips bent at 90°
  • Stalks and branches will become deep red, magenta, or purple
  • Sugar leaf and calyx tips will turn yellow, then dieback. Unlike the appropriate dieback of leaves during flowering, overfed bud leaves will remain engorged while they yellow, then dieback quickly and crisply

Further indications of nutrient burn are yellow, burnt tips on leaves. This will be widespread as over-fertilisation affects the whole plant. Small, burnt tips are common and nothing to worry about. When the yellowing intensifies and advances, however, it is time to take action. Once leaves start to curl and go brown, they are definitely goners.

Nutrient burn can be gradual if the overdose is only slightly stronger. It can also be rapid-appearing, progressing over a few days. The worst-case scenario is a chronic overdose that causes crop-wide yellowing and wilting overnight with leaf curl and lack of turgidity. In this case, if during the vegetative phase, start again. Recovery may be impossible or take longer than restarting completely.

Buds can be affected by nutrient burn as well. During the flowering phase, cannabis changes the way it uses nutrients. The need for nitrogen drops almost to zero while the demand for other compounds like calcium and magnesium increases. An overdose of any kind of additive will cause the same type of burning features.

HOW TO FIX IT

Once your plant’s woes have been identified as nutrient burn, carefully remove all the damaged material. Break off all the damaged leaves. Trace calyx clusters back to their branch and remove the whole florette, just to be sure. Dead flowers and leaves will rot. As soon as possible, flush your growing medium out with clean, pH balanced water. If you are growing with a reservoir, measure the contents with a pH/EC meter and adjust with fresh water.

If you are mixing daily by hand, then calm down tiger, less is more with cannabis. Keep in mind that satisfactory results can be obtained with just plain water for the whole life of the plant.

Prior to returning to a regular feeding schedule, use a specialised plant tonic to nurse the plant back to health. The root biosphere will have been affected, as well as the green parts of the plant. Tonics with silver nitrate, humic and fulvic acids, vitamins and minerals are ideal to restore plants to health.

When returning to regular feeding, use only ¾ strength to avoid burning again. Plants will quickly regain their vigour and continue to grow strongly. Remember to adjust the growing period to allow for time lost when the plants were ill. Adding time to the vegetation photoperiod will not harm the plants. If the burning happened during flowering or with autoflowering strains, then you will just have to take the lower yield on the chin.

PREVENTION

Prevention is always the best policy, so it is a bright idea to develop good habits that decrease the chances of mistakes. First of all, be sure to use the correct nutrients for the appropriate growth stage. Even then, it is a wise idea to only use ¾ the recommended dosage on product packaging. Sometimes, manufacturer recommendations can run things a bit “hot,” which leaves little room for error.

Use an EC/pH meter to check nutrient strength every time, whether hand mixing daily or in hydro reservoirs. Be sure to flush hydroponic systems, grow mediums, and soils to prevent salt build-up in the root zone.

Over-enthusiasm with nutrients can burn marijuana plants. Knowledge is power when it comes to big buds. So, how to prevent and treat nutrient burn?

What Is Overfeeding and How to Fix It

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 growth PPM (Particles per million)
Seedlings 100 – 250
First half of vegging 300 – 400
Second half of vegging 450 – 700
First half of flowering 750 – 950
Second half of flowering 1000 – 1600
End of flowering and harvest 0

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.

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.

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 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.

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.

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 micro nutrients 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 more risky because if the buds brown, they can die and start rotting, ruining your harvest.

Early symptoms Advanced symptoms
Slow plant growth cause by nutrient lock Brown spots on leaves
Leaves curl downwards Burnt tips of leaves
Leaves edges burnt Lower leaves damaged (macronutrient excess) or Top leaves damaged (micronutrients)
Yellowing on the tip of leaves Leaves 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.

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.

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.

Stages Nutrients
Seedling Water
First half of the Vegetative stage ½ dose of Veg. Nutrients
Second half of the Vegetative stage 1 dose of Veg. Nutrients
Pre-flowering stage ½ dose Veg. Nutes + ½ dose Flowering Nutes
First half of the Flowering stage ½ dose Flowering Nutes
Second half of Flowering Stage 1 dose of Flowering Nutrients
Ripening and Harvest Flushing (water)

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.

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 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!

Nutrient overfeeding can happen in any stage of growth, it?s essential to avoid it because it can result in a wide variety of problems like a nutrient burn.