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!
Best recovery from heat stress / salt
Looking for input on best way to facilitate recovery from heat stress and salts.
Large greenhouse plant (green crack), in well amended soil/coco/perlite blend, watered the week previous with RO + 500ppm calmag (1/2 tsp/gal) to prevent deficiencies caused by coco.
Misters cool the greenhouse, failed one afternoon, temps 100+.
Other plants did great. This one the emitters werent placed quite right, not much water near the center root ball.
This one the upper leaves taco’d up, lost most of their sheen, turned an olive type color. Lower leaves and tops shaded by the rest of the plant unaffected and lush. No wilting.
Looks a LOT like this except none of the brown/bright yellow on the background leaves (not my pic) http://img.invalid.com/albums/v385/nlaing/Plant1-Day47-TacoLeaf2.jpg
Tops look a lot like this, with more of the lighter green color at the bottom everywhere:
Seemed to even be some white salt deposits on some upper leaves.
Large ridges between veins on new growth and lots of curled leaf fringes – See bottom right pic here:
Theory is that with hi temps, this one started to dry up, drank up most of the water in the soil. EC went up from the calmag salts, and with less water in the soil, salt concentration went too high.
Seems unlikely to be Mg related with this high of calmag. Prior to arriving at the above now apparently obvious theory, tried a small spot foliar treatment of Mg just to be sure – no affect. Tried some spot foliar treatments of micros, mild tiger bloom, kelp. No affect. Large plant, easy to do a few spot treatments and not affect the whole thing.
Foliared Thrive Alive. Flushed with some straight RO, watering with reduced 100ppm calmag to reduce salt buildup. Working to keep roots from becoming waterlogged (drinks much less). Fixed mister problem.
Few days later, upper leave stems showing a bit of purple. Taco’d leaves unchanged. Upper part of plant remains kind of olive. New growth appears succulent, less pronounced ridges, reduced leaf size and narrow, reduced vigor in upper growth. Lower growth remains lush and healthy.
Would like to do all possible to facility quick and full recovery.
Would aspirin / salicylic acid be worth while? What recipe and best way to apply?
Chitosan (have crab meal on hand)?
Lots of kelp? Water/foliar?
Shade the hurt plant to reduce current stress? Very sunny days, very low humidity at night with misters off, high humidity and large humidity swings during day with misters on. Misters significantly wet the plant with pure RO. Other plants for the most part very happy, a couple of minor leaf fringe curls but very happy.Looking for input on best way to facilitate recovery from heat stress and salts. Large greenhouse plant (green crack), in well amended soil/coco/perlite… ]]>