Take a close look at the damage. Most ailing plants are suffering from improper cultural care. Your best chance of helping the plant is to figure out
what’s going on, so look carefully at the damage. Drooping, yellowing leaves can indicate too much water. Brown, dry leaves and stems may mean too little water. Scorched or transparent leaves? Too much or too little sun. Deformed or nibbled leaves signal pests.
Prune away dead foliage.
You won’t be able to assess the chance of reviving your plant if it is choked with dead leaves. Clip off all dead leaves and branches from plants that look dead and remove all fallen foliage. If you aren’t sure whether a branch is dead, try the scratch test – use a fingernail to scrape off some of the outer layer of skin. If you see green inside, it’s alive and should not be removed. Keep the faith! Any green, flexible stems make it likely you can revive your plant.
Water a thirsty plant.
A plant’s home is its container or garden bed, so dig around in the soil for evidence. If the soil is hard, compacted, cracked and dry, inadequate water is probably the issue. This kind of damage can be corrected quickly if you catch it in time. It’s easy to rehydrate dry plants. Pour water into the plant pot until it runs freely from the drainage holes in the bottom. After that, hose or spray down all remaining stems and foliage. Plants intake water through their leaves as well as their roots.
Let soggy soil dry out.
If the container soil is wet to the touch even though you haven’t watered in a while, the plant’s is suffering from excess water caused by overwatering or poor drainage. Stop watering immediately and let the soil dry out. Check the pot’s drain holes. A small plant container needs a drain hole of at least ½ inch (1.2 cm.) diameter, while a larger plant container needs holes twice that size. If your pot’s drainage is inadequate, it’s time to transplant.
For some plants, getting enough water is not sufficient. Plants like ferns require humidity to thrive, humidity that the average living room might not offer. This can be solved quickly. Place a shallow pan filled with small rocks beneath the plant and add a little water. The water will evaporate and humidify the air near the plant.
Over time, most plants outgrow their pots. The roots may even wind around the inside of the container, making it difficult for them to uptake water and nutrients. Gently remove the plant from its container. If you see more roots than soil, or roots coiling round the inside of the pot, it is time for a bigger container. Sometimes, all it takes to revive a dying plant is a little repotting.
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.