marijuana leaves turning black

How to Prevent and Treat Dry and Crispy Cannabis Leaves

Nothing warms a grower’s heart more than seeing their plants flourish. The opposite is true when they encounter dry and crispy leaves. Such a sight causes worry and concern. Are your plants ill? Will this damage your yield? Could they be dying? We created this guide to put your mind at ease. Learn about the causes and exactly how to treat it.

How to fix dry and crispy cannabis leaves.


Healthy and vibrant cannabis specimens dominate social media feeds. These thriving plants display firm, dark green fan leaves with a waxy shine protruding from robust and sturdy stems. Every grower strives to achieve plants that look half as healthy. However, things don’t always go to plan.

Have you ever walked into your grow space to see dry, crispy leaves hanging on for dear life? It’s disheartening, and far from the luscious foliage depicted on Instagram. If your leaves are looking a little worse for wear, check out the guide below. We’ll cover every possible cause for the condition, and how to fix it.

What Causes Dry, Crispy Cannabis Leaves?

A problem-solver lies at the heart of every cannabis grower. A large part of harvesting a canopy of healthy buds involves a fair amount of troubleshooting along the way, from nutrient deficiencies to pest invasions. Dry, crispy leaves are one of these potential problems. This occurs when plants lose their moisture content, curl up, and feel fragile and crunchy to the touch. Several environmental factors give rise to this issue—nutrient problems, too much water, and excess heat are just a few of the common culprits.

Fortunately, we’ve identified solutions to all of them. Use the guide below to learn what exactly causes cannabis leaves to turn dry, and what you can do to rescue your plants.

Old Age

Cannabis plants don’t stay young forever. Dry, crispy leaves occur naturally towards the end of a plant’s life cycle. During the late flowering stage, as plants divert most of their resources towards forming resinous buds, you’ll notice some fan leaves start to dry and discolour.

Old age largely affects the lower leaves, but those higher up might also begin to lose their moisture content and luscious green appearance. If your plants are otherwise healthy, pest-free, and enjoying ideal temperatures, chances are they are simply getting old.

Fan leaves will appear particularly dry and frail during flushing—the act of restricting feeding around two weeks before harvest to improve the flavour of the buds. An intentional lack of key nutrients will take a toll on the foliage and often cause many fan leaves to fall to the ground.


As a natural phenomenon, you have nothing to worry about. Let nature play its course. Take a clean pair of pruning shears and defoliate the dried and dying leaves to improve canopy aeration and clean up the aesthetics of your plants.

Nutrient Issues

Cannabis plants require a balance of key nutrients to survive and thrive. These natural compounds play vital roles in cannabis physiology, from assisting with photosynthesis to facilitating tissue growth and flowering.

Plants require two key groups of nutrients: macronutrients and micronutrients. As their names suggest, plants require the former in larger quantities and the latter in smaller amounts. Most growers manage to supply their plants with adequate nutrients using either high-quality compost or supplements.

Despite this, plants can still exhibit deficiency symptoms due to pH fluctuations. If the pH of the growing medium becomes too low or too high, plants lose the ability to absorb nutrients. Low levels of molecules such as iron and magnesium—important for chlorophyll formation and enzyme synthesis—can lead to crispy, dry leaves.

A nutrient surplus can also cause dry and damaged fan leaves. Excess nitrogen can burn roots, causing the fan leaves to become extremely dark green and crispy.


Adjust the pH of your growing medium to restore a healthy balance. Cannabis plants thrive in a pH of between 6.0–7.0, whereas hydroponic plants prefer a pH of 5.5–6.5. Use a pH tester to determine the status of your soil. First, attempt to flush out the growing medium with pH-balanced water and test the growing medium again. If the pH level is still out of whack, apply pH correction products available at any growing store.

Also, consider adding mycorrhizal fungi to your soil. These beneficial fungi form a mutually beneficial relationship with plant roots, helping them mine for nutrients in return for sugars.


It’s no secret that cannabis needs water to survive. Plants use this precious resource during photosynthesis, to transport nutrients, and to keep them turgid and strong. Yet, as with everything, too much water does more harm than good.

Overwatering usually occurs when beginner growers take too much care of their plants—they see one speck of dry soil and begin to panic. A constant supply of water means fluid begins to pool in the soil. When plants take up too much water, cells within the leaves bulge and eventually rupture. This causes crusting at the tips and a crispy complexion. Not to mention, excess water creates a breeding ground for damaging fungi, and it flushes valuable nutrients from the soil.


Water your plants intelligently. A slight dryness in the soil is actually a good thing. As a rule of thumb, only water your plant again once the top five centimetres are dry. To keep better track of things, weigh your pots when they’re dry and again when fully watered. Wait for your pots to get close to their dry weight before watering again.

Pests and Fungi

Humans aren’t the only Earthbound creatures with a penchant for pot. Many different species of microbes, insects, and mould all enjoy savouring the taste of fresh cannabis plants. Aphids, caterpillars, and slugs all like to graze on cannabis leaves, whereas plant-parasitic nematodes prefer the taste of roots. Fungi will settle just about anywhere on the plant, as long as it provides them with their favourite conditions—dampness and humidity.

Cannabis plants can take a bit of pest damage, and the presence of a few insects indicates strong biodiversity within the garden. But prolonged and intense assaults can cause them a great deal of stress, possibly resulting in dry and crispy leaves.


Protect your plants! Different species require different tactics. Use predatory insects such as ladybugs, parasitic wasps, and praying mantis to keep pest species at bay. For a second line of defence, sow companion plants such as dill, sweet basil, sunflower, and lavender early in the season to repel and distract damaging insects.

Do you have a feeling your roots are under attack? Inoculate your soil with mycorrhizal fungi; their fine filaments—hyphae—tie down and trap gnawing nematodes. And what about that pesky mould? Simple. Keep your plants aerated with fans or a natural breeze. Avoid overwatering the soil and cover up your crop to protect it from downpours during flowering.

Excessive Heat

Heat has a tendency to make things crispy: bacon, toast, even our skin after too much time on the beach. Leave your cannabis plants exposed under the baking sun in a greenhouse or garden, and you’ll find their fan leaves take on this property, too. Intense heat will cause leaves to lose moisture, dry out, and shrivel up.


If you’re growing outdoors in a particularly hot region, be prepared to defend your plants from a heatwave. Keep some shade cloth and a few stakes on standby, and deploy a DIY setup if the sun beats down harshly for too long.

If you find your grow room becomes unbearably hot, use fans and air conditioning to bring the temperature down. You can even use a sensor and controller rigged up to an exhaust fan to automate this function.

Light Burn

Another pillar of plant life, light enables cannabis plants to create their own energy. Without light, you can say goodbye to cannabis buds altogether. Yet, too much light will burn the upper areas of your plant, causing leaves to crisp over and even damaging high-flying colas. If you let your canopy grow too tall, expect discolouration, dryness, and reduced yields.


Monitor your indoor grow closely. Move your light system up as your plant continues to work its way upwards. If you’re dealing with limited space, use LST and Sc rOG techniques to keep your canopy lower to the ground without sacrificing output.

LED lights are becoming more popular among cannabis growers. As well as being cheaper to run, these lights emit less heat and offer more room for error if your plants grow a tad out of control.

Treating Dry, Crispy Leaves on Weed Plants

If you notice fan leaves becoming crispy and dry, don’t panic! Take on the problem with a level head and remember what you’ve just learned. Revisit our guide, identify the prob lem, and utilise the correct treatment. If you act efficiently, you’ll rescue your plants, solve a horticultural problem, and become a better grower all at the same time.

Dry and crispy leaves don't just look bad, they can stir up quite a panic. But don't worry, check out our guide to discover every single cause and treatment.

Why is my whole plant wilting, curling, with tips turning black and leaves turning yellow?

Question: Why is my whole plant wilting, curling, with tips turning black and leaves turning yellow? Just flipped to the flowering stage. Plant is drinking less than normal.

Additional info: Grown in coco coir with Fox Farms nutrients. Have been growing this plant from a seed and was in veg state growing very well with CFL lights (6500k) 24/7. Very full and bushy plant with many leaves and smelled nice.

Switched to the flowering stage by changing the lights to 12/12 (2700k). Two days later, the plant leaves were drooping, curling inwards, drying out and tips were turning black. Other leaves were a bright green and now almost yellow.

During veg stage plant was getting PH’d water and a mixture of Grow Big and Big Bloom. On 5/9 plant got a mixture of Tiger Bloom and Big Bloom. Plants have always been watered with PH’d water but noticed as of recently it wasn’t drinking as much. As of 5/11, I have flushed the plant with PH’d water 3 times in case there was salt buildup. I have also hand sprayed the plant hoping it would help the very dry leaves that were close to dying. After all this, the plant looks worse today and hoping I can still save. Not sure what has caused it to start dying but please help.

Answer: This plant is showing classic signs of root problems like root rot. The fact that your plant is drinking less than normal also seems to indicate that there’s a problem at the roots. When the whole plant seems to just “deflate” overnight, it’s often caused by root problems. Heat can be a trigger (root bacteria love warm temps) and will also make this problem worse.

Root problems often hit growers in soil or coco coir soon after the flip to the flowering stage, especially with less powerful lights like CFLs. This is because plants use a lot more water when they’re receiving 24 hours of light a day. When you flip to 12/12 light for the flowering stage, it’s easy to overwater plants if you continue watering them on the same schedule.

It’s important to user proper watering practices throughout your grow.

If you think you may have root problems, there are two easy ways to deal with this.

1.) You can purchase Hydrogen Peroxide in 3% – 35% strength.

Mix 1 cup of 3% Hydrogen Peroxide with a gallon of water. For 35% strength Hydrogen Peroxide, mix one tablespoon to a gallon of water.

Water your plants with the mixture to kill any bacteria living in your root area. Unfortunately, hydrogen peroxide also kills good bacteria, which can protect your plant from future infections.

2.) (My preferred method) Conversely, you can start adding Hydroguard to your nutrient-water when you feed.

This will build up colonies of good bacteria that out-compete the bad bacteria and actually promote plant growth.

In addition, the beneficial bacteria will offer protection for those times when the temperature of the grow area rises at a time when you can’t control it. When I first got started with bubbleponics, I had a few tough bouts with root rot.

Over the last few years, I’ve tried many “good bacteria” products including the ($$$) Great White and Subculture B additives, but no product has ever worked 1/4 as good at maintaining healthy roots as super cheap, readily available Hydroguard.

My soil/coco coir / growing medium seems to stay wet no matter what

If the plant medium seems to stay wet no matter what you do, you may need better drainage. It may also help to move plants to a smaller pot until they get bigger and start drinking more.

Make sure that water drains freely from the bottom of your container (it’s recommended that you provide enough water to get at least 20% extra runoff every time you water your plants). You should see water coming out the bottom within a minute or two after watering. Then don’t water your plants again until the soil is dry up to your first knuckle.

For soil/coco coir grows, you generally only want to water the plant when the soil feels dry if you press a finger in it. You can also use the “lift the pot” method to decide when to water your plants (basically wait until your pot feels “light” since the plants have used up all the water). For other growing mediums besides soil, your watering method will vary, but if your plants are drooping and you’ve been feeding them a lot of water, it’s a good idea to cut back and see if that helps.

If your plants are already overwatered, you can try to increase airflow to help the water evaporate more quickly. You can also use a pencil to gently poke some air holes into the growing medium to provide extra aeration and oxygen to the roots. Some growers will even replant a heavily overwatered plant, to get some oxygen immediately to the roots.

Why is my whole plant wilting, curling, with tips turning black and leaves turning yellow? Question: Why is my whole plant wilting, curling, with tips turning black and leaves turning yellow?