What are the Top 8 Common Problems when Growing Marijuana?

What are the Top 8 Common Problems when Growing Marijuana?

Marijuana growers need to learn about the common problems when growing their own cannabis. There are many pitfalls that beginner cannabis cultivators will encounter in their first few harvests. This includes a variety of pests and plant diseases that can afflict your weed and ruin your yield big time. The good news is that marijuana  is pretty resilient and can withstand and bounce back up to a certain point of screw up but your bud yield and quality might suffer.

We have summarized the top 8 problems that cannabis growers (especially beginners) may have to deal with and remedy to save their marijuana harvest. We have also summarized a corrective course of action to dealing with these common cannabis cultivation issues. The top 8 issues that can be encountered when growing weed are broken down in two categories shown in bold.

A) Issues marijuana growers should have under control:

1) Nutrient Issues

2) Incorrect pH range

3) Under Watering & Over Watering

4) Environmental Stress

5) Light Burn

B) Pests and other nasty things encountered when growing weed:

6) Spider Mites / Thrips

7) Bud Rot

8) Powdery Mildew


Photo Source: time.com

1) Nutrient Issues

Your marijuana plants will require three main macronutrients: Nitrogen, Phosphorus, and Potassium. These three make up what is referred to as N-P-K ratio and is usually displayed on labels for nutrients. There is also a myriad of other nutrients that are needed such as Calcium and Magnesium and required micronutrients for healthy growth in your marijuana plants.

What happens when your cannabis plants have a nutrient deficiency?

Many times when a cannabis grower has nutrient deficiencies, the leaves on the marijuana plants will show discolorations or anything that doesn’t look like a healthy green. Consider going with a nutrient schedule from a reputable nutrient supplier and if you have never used that recipe, start your first harvest with less as opposed to more.

What happens when you add too many nutrients to feed your marijuana plants?

When you add too many nutrients, your marijuana plants can experience nutrient burn or lockout. When this happens, your leaves may start curling and the hairs on the marijuana buds may start prematurely turning into shorter red hairs. This occurs when your cannabis plants are unable to use the nutrients because they got overloaded during the grow. Many times this occurs when your PPM is too strong because you added too much of your nutrients. Nutrient overload will will start chemically burning your marijuana. The concentration of salts has built up too much in your growing medium and cannabis plants are suffering from toxicity.

How can I fix nutrient burn for my weed plants?

Nutrient lockout or burn can be eliminated by leaching out the nutrients from your growing medium. This is done by using fresh water (RO-filtered water) to flush out the nutrients and lower the PPM in your soil to reverse the burn. The cannabis plants should be flushed for a few days until it looks like normal growth has resumed. New nutrients should only be added after the nutrient lockout condition is reversed. Then, revert back to your nutrient schedule for your weed plants and monitor your water with a pH / PPM reader. Make sure your PPM is not too high or you will fry your weed plants!

2) Incorrect pH range

Why is having the correct pH important for growing marijuana?

There is a complicated science behind pH balance and the absorption of nutrients by your cannabis plants. Water needed before adding any nutrients should be RO-filtered and should have a very low PPM. The starting pH for this water before you add nutrients should be close to 7.0. Marijuana plants like a slightly alkaline pH balance in the soil or growing medium used (optimal pH – 6.0). The reason for this because the availability of most of your nutrients needed for your weed plants is optimal at a pH of 6.0. The pH for the water that marijuana growers using a hydroponic set up may differ.

3) Under Watering & Over Watering

What happens when a marijuana grower under waters or over waters their cannabis plants?

Incorrectly watering your cannabis plants can happen by a grower by watering too little or too much. You are under watering your marijuana girls if the soil feels dry an inch deep  and the grow pots feel like very light. The leaves on your cannabis will start to droop and turn yellow. To remedy this issue, start watering your weed plants immediately and get them drenched. Consider using a timer to turn your water pump on for regular intervals when the lights are on.

If you over water your cannabis too much or your medium does not have good drainage, these things can create some issues for weed growers also. Marijuana that is over watered will start showing signs of sluggish growth. A cannabis grower will also run the risk of root rot and gnats since your root system is always drenched with overwatering. The top of your soil should be fairly dry but should be moist an inch down.

This type of problem is easy to remedy: just turn off the water and let your marijuana plants thrive for a day or two until the soil does not feel so damp. Consider using a timer at least  once a day when the lights first turn on in your marijuana grow room. It is important to remember that as cannabis plants get bigger, they will require more water as they mature.

4) Environmental Stress

How is environmental stress bad for your cannabis plants?

Environmental stress can come in various forms: light, water, temperature / humidity. Messing up your light cycle can throw your  marijuana plants into stress. I have seen healthy cannabis plants turn into hermaphrodites because my light timers went out while I was on vacation. If your marijuana don’t get the right watering levels, that could stress out your girls.

With regards to temperature, photosynthesis really starts to slow down when the temperature of your grow room reaches past 85 F and completely halts at 90 F. Grow lights needed to grow weed give off a lot of heat so your grow room should way of moving the heat out. This can be done with a good ventilation system that will draw out the heat and an AC unit if needed.

A little humidity can be OK when your cannabis is in the vegetative phase. However, it can be a bad thing during flowering phase when your marijuana plants start developing buds. Lower humidity also helps with resin production (which means higher levels of THC) for your cannabis as you get within a few of weeks until harvest. A marijuana grow room that has high levels of humidity can show signs of powdery mildew and bud rot. No marijuana grower wants to see either of those things because they will hurt your yield and quality of your cannabis buds.

5) Light Burn

How can I tell if my marijuana plants are getting light burn?

Photosynthesis for growing healthy marijuana buds requires light energy. However, too much of a good thing is never good and that is especially true when you start seeing light burn on your cannabis plants. The top of your plants (which will be your top kolas when your weed plants are in flowering phase) will start turning yellow and looking they are frying.

Keep your grow lights at a good distance from your marijuana plants to ensure they don’t get light burn. Topping your cannabis plants when they are in veg or using trellis netting will help marijuana growers battle height issues so they don’t get too close to your lights.

6) Spider Mites / Thrips

How can I tell if my cannabis plants have spider mites or thrips?

If you start seeing white dots on the top of your marijuana leaves, chances are you have spider mites. Spider mites are a common pest for weed plants and is something that many marijuana growers battle on the daily. They belong to the family of mites and are referred to as spider mites because they will lay webs in your marijuana buds. Those webs can ruin your buds for sure!

Check the underside of the leaves with white dots and see if you can spot little white specks crawling around. These nasty vampires grow on the underside of the leaves and suck the life out of your cannabis by taking away necessary nutrients. Spider mites thrive on dark and damp conditions. They become a serious problem for new growers, who do not leave ample room between the developing marijuana plants for good light exposure. Having good air flow helps keeps these things from nesting on your cannabis leaves.

Thrips are a similar pest that can afflict marijuana plants. They are also small insects that are also known to attack weed plants. Thrips  suck on the vital nutrients and will negatively impact the health of your cannabis. Signs of thrips will show up as silver or bronze colored spots on the marijuana leaves.

How can I get rid of the spider mites on my weed plants?

Spider mites and thrips can both be defeated by using neem oil treatment. Make sure your plants are not cramped together and there is plenty of light exposure. Making sure there are no damp spots and plenty of good airflow will help keep these pests away. Neem oil should be mixed with water with a capful of wetting agent. This mixture should then be sprayed on the marijuana plants;  especially the underside of the leaves. Never spray your cannabis when your lights are on; otherwise, you will burn your weed plants. Use a green headlamp when the lights are off and  spray neem oil on your marijuana leaves (don’t miss the underside of the leaves!).

7) Bud Rot

How can I spot bud rot on my marijuana buds?

Bud rot is another serious and somewhat common problem that marijuana growers will unfortunately have to deal with. Bud rot occurs due to the fungus named Botrytis Cinerea. This fungus destroys cannabis buds from the inside by producing a brownish, gray fuzz. A good indicator are dead leaves. Pull them out and look in your marijuana buds to see if you spot this brownish, gray fuzz inside the potentially afflicted bud. Smoking weed that has bud rot is not good for you. If you see a cannabis bud that shows signs of bud rot, cut it and get it out of your grow room. Bud rot can spread real quick to your other marijuana plants.


Photo Source: sensiseeds.com

How can I prevent bud rot when I am growing weed?

This fungus requires damp conditions and stale air. Make sure your marijuana grow room is not too humid. Cannabis plants transpire which is their way of sweating. Having good air flow and maybe using a dehumidifier as your marijuana plants get close to harvest are good ways to mitigate chances of bud rot. As mentioned before, less humid conditions towards the end of your harvest will help your cannabis buds produce more resin.

8) Powdery Mildew (PM)

What does Powder Mildew (PM) look like on your marijuana leaves?

Powder mildew (PM) is another fungal disease, which can attack your marijuana plants. Once you get this fungal disease, it never leaves the cannabis plants. You can only treat powder mildew symptoms but it never goes away. This fungus looks like white flour was sprinkled on the top of your weed leaves. Avoid taking cannabis clones that shows signs of this white powder. If you do not do anything against PM, it can easily destroy your marijuana plants and ruin your harvest.

What can I do if my marijuana plants look like they have powder mildew (PM)?

A sulphur burner can can be used to treat PM on your weed plants but it must be done during the vegetative stage only. Once your marijuana has entered the flowering phase, you can’t use a sulphur burner. You can use sprays on the leaves. Avoid spraying your cannabis buds as this will increase chances of bud rot. There are also organic sprays that have lemon or garlic oils which help alleviate PM symptoms. A baking soda mixture also helps dry out the PM on your leaves.

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