Why Are The Tips Of Medicinal Plant Leaves Brown, Burnt, Or Yellow?

July 12, 2021

The leaves have burnt tips, yellow tips, brown edges ... These are some of the most common symptoms that growers see on their medicinal plants. It can be difficult to identify the cause because many different things can cause similar symptoms. Below I will break down all the reasons why you might see brown tips or yellow leaf edges. Get to the root of the problem and get back to healthy, green leaves!

1.) Overnutrition

There are a few possible causes for discoloration of the tips of the leaves, but one of the most common is the burning of nutrients. This happens when you feed the medicinal plants too high levels of nutrients. Usually the first signs of medicinal plants nutrient burn are yellow or brown tips on the leaves after increasing the total amount of nutrients. As time passes, the brown continues inward and the tips begin to curl. The tips will be dry and will break easily with any pressure.

Cannabis nutrient burn - burnt tips curling up

2.) Light too close to the plants

Plants can burn slightly (like a sunburn) even if the temperature is completely under control. Symptoms are usually concentrated near grow lights. Many growers don't realize that light stress (the lights are too close) can cause yellow tips. This symptom is often mistaken for nutrient burning. You can tell the difference because the yellow tips appear on the leaves close to the light. With the burning of nutrients, the tips are usually brown in color and appear throughout the plant.

In addition, the quality of the grow light that is used is also an essential factor in this case, to solve this problem, you must choose high quality lighting such as ECO Farm, all lights we offer have CE, FCC, ROHS certificates.

Example of yellow tips from light burn (this is NOT nutrient burn)

3.) Incorrect pH

Certain nutrient deficiencies are often mistaken for nutrient burning. Here are some common nutrient deficiencies that can also cause burnt or yellow leaf tips and edges. Almost all of these examples were caused by incorrect pH (the # 1 cause of nutrient deficiencies). To get proper pH, you need a good pH meter.

Yellow leaves with brown edges and tips are the signs of a weed potassium deficiency

A young cannabis plant with the yellow leaves of a potassium deficiency

A potassium deficiency is often mistaken for nutrient burning. One clue is that the brown edges go beyond nutrient burning, and don't affect the tips evenly.

The brown edges and tips of these leaves, along with the yellow margins are signs of a cannabis potassium deficiency

The best way to prevent nutrient deficiencies is to make sure you are giving your plants the correct type of nutrients and a water pH at the proper level depending on your growing medium. But that does not mean that more is better. It is important not to overload your plants with too high levels of nutrients.

What about calcium deficiencies? It used to be that many growers thought that brown tips were caused by a calcium deficiency. However, we have learned that this is incorrect. This is what a true calcium deficiency looks like.

Picture of a calcium deficiency on a cannabis leaf - white background so you can clearly see the brown spots - calcium deficiencies appear on the upper leaves (new growth)

4.) Heat stress

Even if your grow light is a good distance from your medicinal plants, they can still get stressed from excessive heat. Medicinal plants generally prefer temperatures below 85 ° F / 30 ° C, although some strains are more sensitive to heat (shorter, busier strains are often more sensitive to heat than longer, spiny strains). Most plants are fine with a few hot days, but if it's hot every day for weeks, your plants can really start to suffer. Most medicinal plants can withstand a short period of heat, but they don't want to live in a desert! To solve this problem, you need a set of efficient ventilation equipment.

A little heat will cause some problems like leaf tacoing and discoloration, like you can see with this heat-stressed marijuana seedling

5.) Root problems, root rot, or poor watering practices

Chronic overwatering can sometimes cause unusual deficiencies, even if the pH is perfect, like this plant grown in muddy soil. The biggest sign that these symptoms are caused by overwatering and not by pH (or something else) so the plant is always drooping.

This apparent cannabis potassium deficiency looks like a pH problem, but it's actually been caused by overwatering

6.) Bugs or pests

If you ever experience a large infestation, insects and pests can cause a surprising number of symptoms including burned tips or edges. Fungus gnats are one of the most common. They look like little flies buzzing around the top layer of soil. Although some fungal gnats won't actually harm your plants, a ton of them will damage the roots, causing symptoms similar to other types of root problems. This can include brown or burnt leaf edges.

Fungus gnat damage on a flowering cannabis plant

Leaves with brown tips, burnt tips, and yellow tips can be difficult to diagnose because many problems can cause similar symptoms. Once you know the cause, it's easy to fix, but if you don't know, it's impossible! I hope this article has helped you figure out what is causing your symptoms so that you can grow again.

If you want to know more about: growing medicinal plants, or have any questions about growing, do not hesitate to contact us, the ECO Farm technician is always here to help you.

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