Marijuana plants need a lot of light to reach their full potential, but like most things in life, too much is never a good thing. You should always be cautious of how much light is exposed to your plant when growing indoors and how close your plant is to the light source or else you risk light burn.
By light burn your upper leaves will be the most affected and the leaves edges will be curling upwards. If the affected parts of the plant and discoloration are precisely under your grow light then your lights are too close on your plants.
You can turn your buds albino through light bleaching. High-power LEDs and HPS lights frequently cause this when the lights are too close to the top of the plant. If your plant gets burned from the light bleaching then the THC in your plant also diminishes. Although albino buds look really cool, they are basically devoid of all that good THC we want.
Plants need time
Luckily, it is easy to fix a light burn problem. You can move your grow lights further away from the tops of your plants. Plants need time to adapt to changes, so make changes slowly if possible. You don't want to cause stress on your plant which can cause a plethora of other problems.
Heat stress is most damaging in the flowering stage because the plant is no longer growing lots of new leaves. Damage by heat during your budding will reduce yields by obliterating the plant's important leaves.
Heat stress can be prevented simply by monitoring the heat in your grow room. Get a reliable thermostat. Keep your grow room between 73 and 82 degrees Fahrenheit (23 to 28 degrees Celsius) during the plants period of light. During the plants period of darkness keep it between 70 and 73 degrees Fahrenheit (21 to 23 degrees Celsius). If you are having problems keeping your temperature down, try enriching your plans with carbon dioxide ( only when flowering). They will adapt better with a higher temperature and create a high humidity.
Once your plant has reached a certain phase in which it has established large root systems, then they deal better with temperature fluctuations because then they can absorb larger amounts of water. If you experience a heat wave during the vegetative stage of growth then your plant may develop unusually elongated stems. If it's during their flowering stage then the buds could turn out airy (Dutchies call it fluffy), instead of nice and dense.
Another very helpful precaution to avoid heat stress. Is to increase circulation in the grow room by having a fan blow over the tops of the plants to avoid hot spots from developing right under your grow lights. Temperature in between your plants is less of a worry than the temperature hitting your plants directly.
Venting out the heat from your grow room can (and should) also be achieved by using an exhaust system or fan. A carbon filter can be used along with the exhaust system to remove the "unwanted" but lovely smell that gets propelled outward.
Heat stress and light burn, although damaging to your plants, can easily be controlled and fixed. Well... at least when you invest the time to keep informing yourself and checking your grow rooms temperature every day and with posts like this one !!