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Cannabis growing problems

Cannabis plants are resilient. The plant grows successfully all over the globe in many different climates—it’s called “weed” for a reason. 

But many problems can arise when growing cannabis, both indoors and outdoors. Bad weather, bugs, nutrient deficiencies, improper watering, and many other issues can pop up. 

Many issues can arise when growing weed: discoloration of leaves is usually a sign of nutrient deficiency; tiny spots or webbing can mean a bug infestation; stunted growth can be a root problem. 

Check out these articles on specific topics on how to troubleshoot issues with marijuana plants:

Common mistakes when growing marijuana

Here are some common mistakes newbie weed growers make.

Overwatering cannabis plants

New growers are often guilty of giving their new weed plants too much love. As we’ve mentioned before, it’s called weed for a reason—a lot of times the answer is to just let the plant be.

This can manifest in overwatering. A new grower may overthink watering and water too much. 

But the drying out of soil is important too—that’s how roots pull oxygen out of soil and into the plant. Additionally, standing water can stay in soil and cause root rot if not given enough time to dry out.

Remember to only water a plant if the soil is dry 1-2 inches down. Check out our guide on watering for more info.  

Too many nutrients

Similar to overwatering, beginning growers also have the tendency to give plants too many nutrients. A common misconception is that more nutrients equals bigger plants, so just keep adding more and more!

This is a bad idea and will quickly lead to nutrient lockout or other nutrient deficiencies. Nutrient lockout occurs when a weed plant can’t take in any more nutrients. 

A weed plant needs the correct balance of nutrients for it to grow properly and be healthy. If anything, err of the side of too little nutrients—it’s a lot harder to correct a plant with too many nutrients than to add more. Keep in mind that organic nutrients are a little more forgiving. 

Also, keep an eye on the pH of water you use on your weed plants. This overlooked aspect can quickly lead to big problems.

Common problems to look out for when growing weed

Of course there are many problems that can arise when growing weed that should be fixed quickly. Weed plants are rather responsive, meaning they will show signs of distress if they aren’t getting the proper nutrients, have a bug infestation, or some other issue.

Check your cannabis plants regularly for issues. A good time to do this is when pruning, because you’ll be up close and personal with your plants. 

Look at the main stalk of the plant. Stunted growth can be a sign of roots being bound or some other root issue. If one plant is considerably smaller than others or if you’ve been growing it for a while and it seems too small, it could have root issues.

Look for and remove dead or yellowing leaves, and weak or withering branches. If plants are flowering, look for bud rot and mold.

Inspect under fan leaves, as that’s where some bugs live—such as spider mites—and check where the stalk comes out of the soil, as some bugs live there too—in particular, root aphids. 

Cannabis plant leaves should be a dark, vibrant green. Yellowing, discoloration, or spots on leaves are another big giveaway that your plant is sickly.

Check out our guide on nutrient deficiencies for more info.


You can tell what you’re dealing with by eyeball-inspecting the medium and touching it with your fingertips. Keeping track of your plants’ watering schedule will help you determine whether plants are underwatered or overwatered. Soggy substrates that are permanently wet are overwatered. Your fingertips will be wet to the touch after you poke a few cm down to check. On the other hand, dry, infrequently watered mediums are underwatered. Soil will look cracked on the top layer and feel bone dry.

If you’re growing in standalone pots and containers, the best way to judge when to water is by feeling the weight of the pot. Simply pick up plants to tell when it’s time to water. Light pots are the green light. Waterlogged containers will be far more difficult to pick up. Don’t forget to bend your knees too.

Hydroponics systems are more vulnerable to under/over watering. Make sure timers are set correctly and constantly monitor plant behaviour and water pH. Starving, under-watered plants will be droopy, and leaves will sag and yellow. Plus the medium will be bone dry.

Over-watered plants can look similar but usually display more leaf discoloration. Also, the medium will be damp to the touch and as roots rot a foul odour will develop. Worse, the grow op can become a habitat for fungi and harmful microbial life if the problem is not resolved.


Of all the cannabis problems to troubleshoot, overwatering and underwatering can be readily corrected. It shouldn’t take long to figure out whether your plants need more or less water. To be certain every time, lift containers before and after watering to literally get a feel for the weight of wet plants and dry plants.


Most growers try to stick to a feeding schedule. It’s important to maintain an effective wet-dry cycle for healthy root zone and plant development. Monitoring plant behaviour and water runoff will help you achieve this. If you can’t pick up your pots to check by weight when they need watering, you can invest in a water/moisture meter to keep track.


Creepy crawlies always threaten to invade the cannabis garden. Cleanliness and a quarantined grow op are the best ways to keep them from bothering your marijuana. However, should pests attack, it’s most likely going to be spider mites.

Spider mites are mostly an indoor grower’s pest. They are tiny nasty creatures that will web up your bud and utterly ruin your weed. You can only see them with the naked eye when they are crawling around in clusters. Eliminate them immediately with specialist anti-spider mite sprays during vegetative growth. If Spider mites are present in the grow op during bloom it’s game over.

A spider mite infested flowering cannabis plant must be bagged and removed from the grow op immediately. Unfortunately, past vegetative growth spider mites are a nightmare. It’s best to scrap the crop and thoroughly decontaminate the grow space before restarting.

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