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.
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.
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.
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.
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.
How to Spot the 7 Most Common Cannabis Plant Deficiencies by Leaf Symptoms
A cannabis plant is hardy, but its health and vigour will be negatively impacted if it is deprived of essential nutrients. If this is not corrected, it can cause plants to stop growing or even die. Deficiencies in cannabis can be hard to identify, so we have compiled a basic list of what to look out for if things go wrong, and how to fix them.
New cannabis growers are bound to come face to face with a problem or two. Thankfully, cannabis plants are resilient and can stand up on their own in the face of pests or improper growing conditions for a while. But if the problem isn’t rectified in a timely manner, there’s going to be consequences.
One of the biggest mistakes new growers make is overreacting, though. If an iffy situation is spotted, growers should simply acknowledge that and take the time to learn what the problem is and how to properly fix it.
This guide will go over some of the most common problems that can be identified by simply inspecting the leaves. It also will explain how to proceed and get those plants on the road to recovery… and a better yield!
While this definitely isn’t a conclusive list, here are some common growing problems and how they may be identifiable on cannabis leaves (read the rest of this guide for more in-depth help):
- Yellow leaves: Could be a sign of all deficiencies mentioned below, or light burn
- Leaves that curl upward: Could be a sign of potassium deficiency, or overwatering
- Brown leaves: Could be a sign of phosphorus, potassium, magnesium, sulphur, manganese deficiency. Could also be nutrient burn (more solid brown colouring) or heat stress (brown on the edges)
- Leaves droop: Could be a sign of overwatering
- Leaves curl downwards: Could be a sign of potassium or phosphorus deficiency, or overwatering
1. Nitrogen deficiency in a cannabis plant
Nitrogen deficiency is probably the most common deficiency reported by cannabis growers. It’s usually easy to identify and correct as soon as it becomes apparent, although it shares a basic resemblance to several other deficiencies in the early stages.
In the early stages of nitrogen deficiency, leaves appear to be too light in colour—almost yellowish-green—compared to the desired deep green of healthy leaves. Nitrogen-deficient leaves also typically have slightly darker veins compared to the very light colour of the leaf tissue itself—although the contrast is not as marked as in some other deficiencies.
At the other end of the spectrum, nitrogen toxicity results in leaves taking on a very dark green hue that can look almost black in extreme cases.
In severe cases of nitrogen deficiency, the leaves appear lighter and lighter in colour, and eventually begin to dry out and die. The larger leaves on the lower and outer parts of the plant are often the first to be affected and the first to die.
How to fix nitrogen deficiency
If nitrogen deficiency becomes apparent in the later stages of flowering, it doesn’t need to be corrected. In fact, it’s natural for the older leaves to drop off and die at this point as they are no longer needed.
However, a nitrogen deficiency in vegetative growth or early flower can severely impact overall yield and quality, as it affects the plant’s ability to photosynthesize energy. Nitrogen deficiency can usually be corrected by simply increasing the strength of your normal NPK-based feed, but if fine-tuning is required then nitrogen-only additives are not hard to find.
2. Phosphorus deficiency in a cannabis plant
Phosphorus deficiencies are rare, but should be cause for concern. If it affects plants in the vegetative stage, it can cause reduced growth rates, small leaves, weak roots, and plants that are generally lacking in vigour. In the early stages, phosphorus deficiency usually causes leaves to appear dark but washed-out, with very dark veins and somewhat lighter leaf tissue.
As it progresses, purplish discolourations begin to appear on the main part of the leaves and the leaf edges begin to turn brown and curl downwards. The leaf petioles (the small stalk attaching the leaf to the main stem) may also begin to turn a purplish colour. In the final stages, large patches of the leaves become purplish-brown and dead, while the remaining sections turn mottled yellowish-green.
Again, phosphorus deficiencies usually affect the outer, lower leaves first. Unlike nitrogen deficiency though, phosphorus deficiency at any stage is cause for concern, as the plants continue to require high levels of phosphorus throughout the flowering period.
How to fix phosphorus deficiency
There are several ways you can fix a phosphorus deficiency. Just remember to take it slow. If any remedy is overdone, the plant could end up not getting enough of other nutrients and fare worse than if it had been left alone. With that said, here are a few methods for fixing it:
- Temperature – Don’t let the temperature drop below 15 degrees Celsius, as colder temperatures make it difficult for cannabis plants to absorb phosphorus.
- Water correctly – Ensure the plants are watered correctly. Too much water and soil that’s too packed can lead to a phosphorus deficiency.
- pH Products – Use a pH up or pH down to ensure the roots have the correct pH level. It should be between 6 and 7.
- Add Phosphorus Sources – Add sources rich in phosphorus to the soil. Some sources that can be used are fish meal, warm casting, soft rock phosphate and crab shell. (Or simply use a good organic fertilizer that automatically ensures balanced soil)
Once the problem is corrected, new leaves shouldn’t show the discolouring signs of phosphorus deficiency. Keep in mind that old leaves will likely not recover and that’s perfectly normal.
Tutorial: Cannabis plant nutrient deficiencies can be hard to identify. Use this guide to help you figure out what’s wrong and how you can fix it.