Autoflowering Plant Heat Stress Symptoms
Your plants can only withstand a certain amount of heat and light. After a certain point, your autoflower will start showing signs of stress on the bud or leaves. Your leaves can get yellow or brown, appear burnt or bleached, it’s also common for the leaves to fold in a taco shape all of those symptoms and more we’ll explain here.
1. What is Heat Stress?
Heat stress can happen indoors or outdoors, it occurs when your autoflower is exposed to high temperatures for a long period of time.
This can cause a wide variety of problems, stunting growth, affecting yield and ultimately killing your plant.
2. What Causes Heat Stress?
Heat stress indoors is a result of not adjusting your climate for optimal growing. Outdoors it’s harder to control but in both situations, heat stress is caused by the same factors: low humidity, high temperatures, and high light intensity.
Let’s examine heat stress factors and learn what solutions can be applied to each situation.
The ideal humidity for an autoflower is 60% depending on the stage it’s in. Very low humidity can make plants more likely to get heat stressed. Sometimes you’ll get symptoms that look like heat stress even if it’s not that hot, they can be worse because the plant is being affected by very low humidity.
Low humidity won’t stress your plant, it can affect growth and yield but there won’t be any apparent symptoms unless it is combined with high light intensity and/or high temperatures.
If you’re growing indoors, there are a couple of solutions. You can use a humidifier for a long term solution or you can place buckets filled with water inside or around your grow tent, always checking the hygrometer to keep humidity at an optimal level.
Outdoors there’s not much you can do, try to place your plant in the shadow for a few hours a day, we also recommend to water more times with less water throughout the day, this should keep the roots cooled down.
The optimal temperature to grow autoflowers is around 25 Celsius (77f). Heat stress is primarily caused by high temperatures. Your plant will always show you when she’s not happy, it’s essential to keep an optimal climate for your autoflowers, keeping in mind that flowering plants are even more susceptible to heat stress.
Plants in the vegetative stage usually start to fold leaves inward in a taco or cup shape and can start to damage leaves even if the temperature is not that high. Combined with low-humidity it can wreak havoc.
As said before, plants in flowering are even more susceptible and if a lot of leaves are damaged it will respond to overheating by growing buds with less potency and eventually with abnormal growth of buds. In result they will look like what is known as foxtail. It does not always look like that, sometimes it’s just an abnormal growth of bud.
What happens is the plant is trying to abandon the heat-damaged bud and start a new one. At this stage you should see a lot of white pistils growing.
Solving this primarily revolves around increasing air circulation in your grow space, if this is not possible an oscillating fan blowing on top of your plants might be a good alternative. If you’re growing outdoors you should try to cool down your roots. Instead of watering your plant once a day, you should water it multiple times with less amount of water. This way you keep the medium moist and it can help to cool down the roots.
Tip: If the damage is already done, use seaweed kelp fertilizers to help your plant recover, they contain cytokinins which help reduce stress.
High Light Intensity
Light burn or light stress only occurs indoors, it can happen when transferring a plant from a weak to a strong light or if the light source is too close to your autoflower. It also can happen to older leaves that have been exposed for a long time but that’s not common.
Usually grow lights come with height recommendations for both stages (vegetative and flowering), you should always experiment and test what works better but you should never start with placing the lights too close.
The most common symptoms are yellowing, burned leaves and bleached buds (when the bud starts to turn white). The first signs a plant is getting too much light is when the leaves start pointing up (sometimes you don’t even see any symptoms until the yellowing starts).
Often the leaves start turning yellow but the veins stay green and may appear pale. If it goes for a long time, leaves will start to taco, the tips start to turn brown and crispy, and eventually start breaking to touch.
Tip: Light burn should not be confused with a nitrogen deficiency, we recommend paying attention to the small differences. Nitrogen deficiency starts from the bottom and moves up, nitrogen-deficient leaves will fall on their own. Light-burned leaves are hard to pluck-off and in most cases, the yellowing will occur on top of the plant.
Bud bleach is most common with LEDs, basically happens when the bud gets too much light and starts turning white at the top, the affected part will lose potency and it’s smell.
If your plants are getting too much light, try moving your lights further away, removing some of the lights or look into a dimmer to control the intensity of your grow light. To prevent bleaching you should look into low stress training to prevent your plant from stretching too much.
Unfortunately, there is no way to bring your plants back to normal other than let them grow it out or harvesting before they die in the worst cases. The best way to prevent this is by taking all precautions before it happens.
3. In Conclusion
When making changes to your plant’s environment it’s best to make changes as slow as possible. To keep a good climate for your autoflowers you need to prevent a sudden change of humidity, temperature, and light. Keep in mind these 3 factors as they are tied together when talking about climate.
A thermo hygrometer is an instrument that measures temperature and humidity, always use one when growing indoors. It costs around 15 bucks and it can help save your harvest if you’re having the problems we discussed above.
Your plants can only withstand a certain amount of heat and light. After a certain point, your autoflower will start showing signs of stress on the bud or leave
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!