How To Revive Sick Cannabis Plants
When your cannabis plants are sick and stressed, it’s important to immediately identify the problem. That’s when the real process of reviving your cannabis begins. Here’s what to do to help your plants recover and thrive after a major setback.
Your plant is wilting, you notice the leaves turning yellow or forming unsightly spots, or maybe it’s refusing to grow altogether. There are many reasons why cannabis plants can become sick, from issues with watering to pest infestations, inadequate lighting, heat stress, and more.
No matter the reason for your plant’s sickness, the first thing you’ll want to do is diagnose the problem. When you have addressed the cause(s) of your plant’s condition, you obviously want to revive it as fast as possible. Here are some things you can do to help plants recover from infestations, illness, and more.
PROBLEMS IN YOUR GROWING ENVIRONMENT
If your plant appears to be dying or suffering hard, it is unlikely that a minor issue is occurring. Most of the time, a rapid descent in the health of your plant signals a fundamental issue or invasion. This can involve problems with environmental conditions, microscopic infestations, and other culprits.
CHECK TEMPERATURES AND HUMIDITY IN YOUR GROW ROOM
If you’re growing indoors, the first step to reviving your plants is to check the temperature and relative humidity of your tent or grow room. The ideal temperature for cuttings and seedlings is between 20–25ºC. As the plants get older, they can tolerate a bit more, up to 28ºC. Everything above this is excessive and causes stress, which will make it much more difficult for your plants to recover.
Likewise, the humidity levels of your room must be kept within a certain range depending on the phase of growth. An optimal humidity level for flowering plants is 40–50%. Plants in the vegetative growth phase can tolerate a more humid environment, from 40–70%. If the humidity is too high, you need to look into better ventilation for your grow space. A dehumidifier is the best, albeit expensive option here. Your sick plants will have a hard time recovering if their environment is not stable and optimal.
AVOID HEAT STRESS OUTDOORS
Despite cannabis loves plenty of light and warm temperatures, if you grow outdoors in the summer, heat stress and excessive sun can be a problem, especially for plants recovering from illness. If you have your plants in pots and they look stressed from too much heat, move them to a shadier location. Less heat and direct sun will make it easier for sick plants to get back up to strength.
LOWER YOUR LIGHT LEVELS
Cultivators normally keep their wattage levels as high as possible to encourage plants to grow faster. More light means the plant is working harder and will likely produce a greater yield. On the other hand, a plant that is working extra hard is more susceptible to deficiencies and other problems. One way to give your sick plant a break is to decrease the light intensity. Move your lights higher up and further away from your plants, or decrease the wattage.
When you grow indoors with your lights on a timer, you can also cut down on the daily light hours your plants receive. When you reduce the light hours for the vegetative phase to only 17 or 16 a day, this will give your plants more time to “rest” and recover.
FLUSH YOUR PLANTS
Many problems with sick cannabis plants can be due to overfeeding. When your plant can’t take up the nutrients that you provide, salts and minerals will accumulate in the soil over time. This will change the pH level at your plant’s root zone, making it more acidic—beyond the small pH window that cannabis has for healthy growth. As a result, your plant is not able to take in nutrients, even if they are present in abundance. When this happens, further feeding only makes it worse.
In almost all cases where your plants show signs of nutrient deficiencies or nutrient burn, you should give your plants a solid flush. Flushing means that you rinse out the excessive salts with pure, pH-balanced water to restore the optimal pH of the growing medium.
To flush your plants, drench the growing medium with water numerous times. It should be ample enough that liquid comes out from the bottom of the container each time. For example, if you grow in 7l pots, flush your plants with 14l of water. When you grow in soil, your water should have a pH of about 6.5pH. After the flush, you can begin giving nutrients again, starting with ½ or ¾-strength doses. You can slowly work your way up from here to avoid putting plants under any additional stress.
REPOT YOUR PLANTS
Repotting your cannabis plants into new, larger containers with fresh soil can also help bring them back to life. Choose a container that has plenty of room for the roots to grow. If your plant is severely damaged due to overwatering (root rot) or various fungi, consider trimming its foliage. When the roots have fewer leaves to support, they can recover faster.
KEEP PESTS AWAY
Plant infestations from spider mites, fungus gnats, fruit flies, and other insects are all too common when you grow cannabis. When you have finally gotten rid of the pests, you want to make absolutely sure that they don’t return. Pest infestations can really ravage a plant, so it certainly needs optimal care and time to be revived.
In terms of keeping the pests away, there are natural insecticides like neem oil that can be highly effective. You can even use it as a foliar spray, applying it to your leaves every 2 or 3 weeks. However, be careful during the flowering phase as you do not want the overbearing taste of neem oil on your buds! For fungus gnats, you can also set up yellow sticky traps, which will catch most of them.
Neem oil serves as a completely natural way to protect your cannabis plants against pests.
Neem oil serves as a completely natural way to protect your cannabis plants against pests.
SUPPLEMENTS TO HELP YOUR SICK PLANTS RECOVER
There are certain supplements you can give to your sick plants to reduce stress, support their development, and increase their resistance.
For those growing in soil, compost teas are an excellent supplement to support the recovery of sick and stressed plants. Compost teas can make your plants grow faster and more robust, making them less susceptible to diseases and deficiencies. Some cultivators make their own compost teas at home, although they can also be purchased at most well-sorted grow stores.
Silica has properties that strengthen the cell walls of your plants, which makes it helpful for increasing their resilience. Furthermore, it makes certain minerals and nutrients more available while protecting the roots as well.
Seaweed contains minerals and other micronutrients, and has been shown to help reduce plant stress. While its mechanism is somewhat unknown, seaweed has long been part of the weed grower’s arsenal.
With the above tips, we hope you are able to revive your precious cannabis plants and make it to a hefty and healthy harvest.
In this guide, you'll learn how to help revive your sick and stressed cannabis plants after infestations, nutrient deficiencies, and much more!
Help, My Leaves Are Dying!
I hear this question all the time…
“What’s wrong with my plant? The leaves are…”
Today I will clear up the 3 most common reasons that your marijuana plant’s leaves are dying…
3 Most Common Reason for Discolored Leaves
Other Cannabis Problems & Symptoms
#1 Reason For Dying Leaves: Incorrect pH at the Roots
The #1 reason new growers have dying leaves is because of a pH imbalance . This is because the roots of your marijuana plants need to live in a certain pH in order to properly absorb nutrients. So the pH around the roots will actually affect which and how much nutrients can be absorbed by the plant.
Yes, that’s worth repeating. You will prevent nutrient problems by checking and adjusting your pH in your marijuana grow.
That is why when new growers think they have a nutrient deficiency, often the real problem is that the pH at the roots is off, and the plant can’t get access to the nutrients even though they’re present.
So what is pH?
The pH scale goes from 0 to 14 and measures how “acidic” or “alkaline” a solution is. Below 7 is acidic and above 7 is alkaline. A pH of 7 is the neutral point, and pure water has a pH close to 7.
But that all sounds so complicated!
Checking and maintaining your pH is a relatively simple process that anyone can learn. I have a video below to demonstrate how easy and quick it can be to manage your pH!
Plus, the important thing is to maintain a proper range around your root zone. It’s isn’t critical to maintain an exact pH like 6.2 or anything like that. In fact, it’s better to let the pH range slightly over time because different nutrients like different pH ranges, as you’ll see in a second.
Managing pH: What Do I Need to Know?
You have several options for managing your pH. But no matter what option you choose, youwill need to invest in some way to measure pH.
You can measure pH with…
PH Up/Down or a natural pH adjustment method*
The process of maintaining pH looks like this:
Measure out the water you are going to feed your plants
Add all nutrients and/or supplements to the water
Use one of the options above to test the pH of this water
Use pH Up/Down or a natural pH adjustment method to adjust the pH of your water into the proper range
The optimum pH for marijuana in soil is between 6.0-7.0. The optimum pH in hydro is between 5.5-6.5 (this includes growing in a soilless growing medium like coco coir). It’s a good idea to allow the pH to change slightly over time within the prescribed ranges, especially in hydroponics. Take a look at the charts below to see how different nutrients are absorbed at different pH levels, so you can see why it’s good to let your pH range over time.
Each Nutrient is Best Absorbed at Which pH Range?
What If I’ve been following these steps, but I’m still having problems?
If you’ve been adjusting the pH of the water going in, but are still having nutrient deficiencies, check the pH of the water coming from your roots . So this means check the pH of your runoff water(the water that drains from your flower pots), or the water in your reservoir.
You may find that the pH is higher or lower than expected. This is why it’s important to check the pH of the water coming from your roots when you’re running into nutrient problems.
For example, let’s say you watered your plants with nutrient water adjusted to a pH of 6.0, yet the runoff water is coming out with a pH of 4.0. This often happens because there is nutrient/salt buildup around the roots (usually from adding too many nutrients over a period of time). You need to remove the buildup. A common way to remove salt buildup is to flush the plant with about 3x as much plain, pH’ed water as normal. Then go back to your normal feeding schedule (make sure you check the runoff pH again afterwards, to make sure that your flush worked).
In hydroponics where the roots are growing in water, it is common for the pH to rise over time. This is partially because oxygenating your water (for example using an airstone) actually raises the pH. This is why it’s important to keep checking the pH until you’ve grown familiar with how the pH tends to play out with your system and your water/nutrients.
Wait, why do I need to check the pH of my run-off water?
The pH of your soil or potting mix can fluctuate as nutrients/salts begin to build up. This happens most often when you are regularly feeding more nutrients than your plant can use.
Checking the pH of your run-off water is an important step to diagnose problems with the pH around your plant root zone. This step is especially important for new growers and those who are having issues with nutrient deficiencies.
If the runoff pH is much higher or lower than expected, chances are you have unused nutrients or salt build-up near the roots that are raising or lowering the pH of your root zone.
When this happens, you can remove this buildup by flushing your soil or soilless mix with about 3 times as much pH’ed water as the volume of your container. You can also flush your plant to remove extra nutrients if you’ve over-fertilized your plants and they’re showing signs of nutrient burn.
This will wash away the buildup and help “reset” the pH of your root zone back to the proper level.
Some growers choose to flush their plants every 3-4 weeks regardless of whether they notice problems to prevent buildup, though this is usually unnecessary unless you are chronically overfeeding with nutrients.
After someone has been growing the same strain of marijuana, in the same medium, with the same nutrient solution, etc. for a while, chances are they will become very familiar with their growing style and won’t need to check the pH of their runoff water unless they notice problems.
Show Me Step-By-Step: How Do I Check the pH of My Water?
NOTE: The the blue and orange pH up/down bottles you see at hydroponic growing stores are not designed for organic growing. While some growers believe it is okay to add pH up/down in small amounts after you’ve mixed your nutrients into your water, other growers feel this may kill the microorganisms that make organic growing so effective.
If you’re an organic gardener and worried about using pH Up/Down, there are natural ways to adjust the pH that definitely won’t harm your living soil.
A cool fact about pH:
The type and amount of nitrogen used in a nutrient bottle has a big effect on how much it will affect the pH of your water.
Using this knowledge, a smart grower could buy or mix up nutrients based on the current pH levels of their water so that their nutrients auto-correct the pH.
#2 Reason For Dying Leaves: Watering Plants Incorrectly
Ok, you have successfully made sure you’ve corrected the pH, and you’re still seeing dying leaves, or leaves with problems.
Chances are you have a watering/root problem.
When growing in soil or a soilless growing medium like coco coir, this is usually caused by poor drainage, or over/under watering.
To properly water your marijuana plant every time, use this technique:
Every time you water, add enough that about 20% extra runoff water has drained out the bottom (if you don’t have drainage holes, or if water isn’t draining, this needs to be fixed immediately or you will run into lots of other problems).
After you’ve watered your plants with 20% extra runoff, then don’t water them again until the growing medium is dry enough to stick your finger in to about your first knuckle without feeling moisture.
In hydroponics where you’re growing with your roots directly in water , a root problem doesn’t result from over/under watering, since you don’t water your plants.
The problem in hydro usually results when plant roots start “drowning” because they can’t get access to enough dissolved oxygen in the water.
The way to fix this is to oxygenate your water with an air stone, or otherwise get more oxygen to your plant roots.
In both soil and hydro, you can also see signs of root problems because of a condition known as “root rot.” This condition will give you brown, mushy, smelly roots.
Root rot is often the result of bad watering practices, high temperatures, or poor drainage, but sometimes root rot can appear out of nowhere.
When this happens, a great cheap supplement that seems to completely decimate root rot is Aquashield. There are also other root supplements that are more expensive such as Great White and Subculture B, but I’ve always had the best results with the much cheaper Aquashield.
#3 Reason For Dying Leaves: Nutrient Problem
Ok, you’ve ruled out the #1 and #2 most common reasons for dying leaves. You may actually have a nutrient problem.
GrowWeedEasy.com will teach anyone with any budget how easy it is to grow their own cannabis.