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Common Cannabis Growing Mistakes – And How to Fix Them

Cannabis growing mistakes are common, so don’t worry. Here’s a list of the most common and how to fix them!

There’s nothing quite like growing your own plants. Watching them bloom in response to your tender loving care is extremely satisfying. And the sight of healthy flowering plants is a sight to behold.

At the same time, the sight of an ailing plant can be as gut-wrenching.

A new grower’s biggest mistake is failing to do adequate research before starting to grow. Cultivating any plant to be used for consumption is a lot more sophisticated than some believe, and those people invariably learn the hard way – with ruined crops. Buying the right seeds and researching the best conditions for them to grow is half the battle. Guesswork is not something you want to rely on. 

Also, choosing the best method – Indoor, outdoor, hydroponic, soil, Sea of Green, Screen of Green – and knowing how to go about it will give novice growers a good head start on the road to successful cultivation. Doing your homework ahead of time is just common sense.

There are numerous potential pitfalls in growing cannabis plants. But if you know what to look for – and most importantly, how to act – disaster can often be avoided if you act swiftly and correctly. Whether it’s your first time or you’re in need of a refresher, here’s a look at some of the most common cannabis growing mistakes and how to fix them.

*Laws and regulations regarding cannabis cultivation differ from country to country. Seedsman does not encourage growing cannabis in regions where it is not permitted.


A marijuana plant will always tell you when it’s unwell. So knowing the signs of an ailing plant allows a quick diagnosis and hopefully a quick fix. An overwatered plant will display drooping leaves (the whole leaf, not just the leaf tip), and the leaves will be firm to the touch. You may also see yellowing of the leaves, known as chlorosis, as a symptom of overwatering. Although yellowing leaves can indicate other problems such as nutrient deficiencies or Ph level issues. 

Finally, if you’ve overwatered, you’ll likely see slowed growth in the plants as they can no longer access oxygen efficiently at the root level. This could slow growth or stunt it entirely. Be wary of overwatering just after germinating as well. 

How to Fix Overwatered Cannabis Plants

Ensure your pots or containers have adequate holes for drainage. Check your drainage for blocks that could be causing issues with clearing excess water away. Avoid unnecessarily watering your plants by checking the growing medium, too. If you poke down into your soil about an inch and it’s wet, you shouldn’t water your plants again until that soil is dry or lightly moist at best.

If your plants are indeed overwatered, give the medium a couple of days with no watering to dry out. Depending on the damage you might need to pot any overwatered weed plants in a larger container with new, dry soil to help absorb some of the wetness from the overwatered root mass. Be aware this could lead to a far larger plant, depending on the growth stage at the time.

Nutrient Burn

Nutrient burn can occur for numerous reasons. It is a clear indication you’ve got something wrong – possibly overfeeding nutrients or mixing too vigorously. 

Nutrients are a small supplement to your grow and should be used as such. More nutrients do not mean bigger, better plants, so knowing the correct amount to feed your plants falls under the category ‘necessary research’. If your nutrient levels are too high, the flow of water through the plant gets disrupted, causing burnt tips on the leaves, which appear yellow at first, then bronzed or brown, crispy, and inward-curling.

These symptoms can appear on one or two leaves or all over the plant. Yellowing leaves can be symptomatic of other conditions such as potassium deficiency or Ph fluctuations. Knowing the signs of each is important to take the correct action.

It’s important to know that if nutrient burn is left untreated; the buds will contain small traces of extra nutrients, impacting the taste, leaving them unpleasant and chemical-tasting. Once in the flowering stage, nutrient burn can be harder for the plant to recover from and harm your yields.

How to Avoid or Fix Nutrient Burn In Cannabis Plants

Using the correct nutrients from the outset is a good start – only ever use nutrients designed for cannabis plants. If you’re stuck, nutrients for tomato plants can be used, but this should be a plan B. Also, ensure you’re using the proper nutrients for the grow stage – vegetative and flowering stages require different nutrients and levels.

Many experienced growers suggest viewing the feeding instructions on the nutrients as maximum. Start with a lesser quantity than the product recommends – maybe half the recommended amount. Work your way up if needed.

If you’ve gone too far and see the signs and symptoms of nutrient burn, begin by flushing your system (if growing in soil or coco) with plain pH’d water. Do not add any further nutrients, and wait to see if the plant uses up the excess nutrients and recovers. You’ll likely lose the damaged leaves but shouldn’t see any new damaged leaves forming on your plants.

If you’re employing a hydroponic set-up, you can dilute the nutrient level by adding pH’d water, or if possible, change out your water completely, adding nutrients at a lower level than before. 

This should stop the spread of nutrient burn quickly. You’ll lose the damaged leaves, but you shouldn’t see any new damaged leaves appearing.

If you’re raising the nutrient levels, always remember to do so in small increments. Observe changes before deciding whether to increase further or not to avoid the risk of acidity.

Bud Rot

Bud rot, also known as Botrytis or root rot, is a grey mould that occurs in cannabis plants. It indicates poor airflow and high moisture levels. This can be a cultivator’s worst nightmare. If you see it, you’ll have to move swiftly. It can destroy your entire crop in a matter of days. Unfortunately, once you’ve got it, the only option is to discard the infected areas of the plant and adjust your environment to prevent further spread. It sadly happens a lot to first-time growers. 

Bud rot is easily seen, although it’s harder to identify in its early stages. It can attack every part of the plan. However its most commonly found on buds during the late stage of flowering. 

Be on the lookout for webbing appearing on the leaves, greyish in colour. The webbing contains structures that are home to fuzzy spores, which are activated and released, causing the untimely death of your plants. Symptoms of grey mould include grey/brown colouring and dry or lifeless, wilting leaves which can fall apart if touched. 

Dealing with Bud Rot

The best way to deal with bud rot is to avoid getting it in the first place – but how?

Avoiding bud rot is on you, for the most part, as the condition is symptomatic of environmental issues. Cannabis growing takes place – indoors especially – in warm and humid environments. If the environmental factors are not finely balanced, you leave your cultivation area vulnerable to the evil clutches of Bud Rot. Invest in a humidity meter to monitor and control the humidity levels in the area, and keep it under 60%. Inspect your plants daily and diligently, and if you should see any signs of bud rot, get straight to work pruning them off, but take great care to remove those cuttings immediately. 

When the pH is in the wrong range, a plant can’t uptake nutrients properly either.

The best practice is to remove them from the area as you cut them, rather than allowing them to fall to the floor to gather them up later – you don’t want these infected cutting coming into contact with healthy leaves, buds, or soil. Destroy all infected parts you’ve removed in an area away from the grow.

Good hygiene practice also goes a long way in helping minimise bud rot. Wear gloves at all times, and clean your pruning gear before and after use, but take further care by keeping all your equipment clean, including scissors, stakes, labels etc.

Light/Temperature Mismanagement

Depending on what time of year you’re growing, you may have no problems at all with this, or you could run into a slew of problems – especially if you’re growing in winter. At that time of year, temperature fluctuations can be extreme between nighttime and daytime, which will undoubtedly cause your plants stress and jeopardise your grow. If that temperature creeps too high, you’re inviting trouble which can come in many forms.

With lighting, resist the temptation to skimp on equipment. Buy a timer to control the on/off of your grow lights, as no matter how punctual you plan on being, hold-ups are sometimes inevitable. A few minutes late to flick the switch on those lights can make a massive difference to the stress levels of your plants. They need enough light to thrive, but too much can be fatal.

Cannabis (not autoflowers) is a photoperiod plant, which means the growth depends on light exposure.

Avoiding Hermaphoditing

Stressing your plants can cause them to turn hermaphrodite, which you most certainly do not want if you’re growing for consumption. This problem can also be caused by having your lights too bright or too close to your plants.

You’ll be able to identify hermie plants by their yellow colour and banana shape around the pistils, or hairs, of the buds.

By maintaining the best environmental conditions in your grow space at all times and practising flawless hygiene, you significantly reduce the risk of your plants turning hermie. If you find your plants turning hermaphrodite at the beginning of the flowering period, remove them from the grow space entirely to avoid the risk of your entire crop becoming pollinated. If your plants turn hermaphrodite at or near the end of the flowering cycle, harvest as much cannabis as possible—separate any seeds from the cannabis.

Buying your cannabis seeds from a trustworthy outlet is an excellent place to start. Good genetics helps lessen the number of cannabis growing mistakes one can make.

Incorrect Use of Fans

If you have no fans in your growing environment, that isn’t good. If you have fans, but they’re too powerful, that isn’t good either. Get an adjustable fan with different speed settings, and set it up about a metre away from your plants with enough of a current to cause a light shimmer or rustling of the leaves. 

The breeze from the fan should not cause the plants to bend or push against each other. Oscillating fans are great for smaller grow rooms and tents because they can distribute air nicely and evenly over the plants. This is necessary for indoor growing to fuel photosynthesis and allow the plants to breathe. Fans also help maintain the proper humidity level in your grow space, and without airflow, you’re inviting pathogens to take hold.

Over Attending to Your Plants

Over pruning, shaping, constantly adjusting lighting height, feeding schedule and so on are common cannabis growing mistakes made by a newbie. The temptation is strong – you come in with good intentions and want to keep everything neat, uniform, and orderly. Plants need love, but sometimes, the best thing you can do is set up your environment correctly and let nature take its course.

Other than monitoring nutrients, watering when necessary and checking for pests and pathogens, try to resist the urge to micromanage every little thing.

Overhandling your plants is possible and can do more harm than good. Keep up your checks, but don’t get into the habit of constantly adjusting every little thing. Neither you nor your plants should be stressed!

Cannabis Growing Mistakes are Common, So Don’t Stress!

Choose your strain carefully, and research best practices for growing that particular strain – medium, environment, nutrients – know as much as you possibly can about what you’re growing and how best to grow it. You may face problems along the way but act swiftly and never in haste to troubleshoot any issues with your plant growth. 

Be patient. It doesn’t matter if you’re growing CBD or THC-heavy flowers, you need to wait for most of the trichomes to switch from clear to white before harvest time. 

It’s a good idea for indoor cannabis growers to set up the environment a few days before introducing seeds or cuttings. Then monitor the changes in the room between day and night – this will give you a good idea of any extremes to expect in the area and allow you to adjust accordingly before introducing the cannabis, rather than finding out the hard way. Be prepared, and have fun.

If you’d like some more support, the Seedsman Community is made up of thousands of growers from experts to beginners and are always ready to help address any and all cannabis growing mistakes.

Check out this page to find links to our Discord, Reddit and Facebook pages, We’re all in this together.

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

This post is also available in: Spanish

Duncan Mathers