10 Mistakes to Avoid When Growing Cannabis

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Added 15 April 2023

Start any new hobby, and you are bound to make mistakes — that’s okay — it’s part of the journey. But some mistakes can cause a lot of trouble, waste money, and even demotivate you. 

When you are growing cannabis, these mistakes can cost you your plants. We all want to grow the healthiest plants that produce bushy buds, and in the process, many mistakes can (and do) happen. 

Most of these mistakes don’t have a long-term effect on your plant and can be solved easily. These mistakes are natural for new growers, and almost all growers make them when they start out with their cannabis cultivation.

However, some mistakes are not even worth risking. That’s why we say that it’s better to learn from others who have already been there. 

But, what are these mistakes? Here are the top 10 mistakes you must avoid when growing cannabis. 

1. Being Oblivious of Your Plant

Being Oblivious of Your Plant

The first mistake often happens before many growers germinate their seeds — when they get their hands on the seeds without knowing what they really are. Sure, it seems terrific when you purchase some cheap (or free) seeds, but the problem here is that you may not know what they really are.

More specifically, you don’t know the genetics of the seeds. That’s a recipe for a bad start to your gardening journey. 

Cannabis boasts of various seed varieties, and all cannabis strains vary drastically. Some are tall, some are short, some grow colorful buds, some grow green buds, some are potent, and some are mellow. You need to know exactly what you are getting into.

The complication doesn’t only arise in terms of the strain’s physical appearance or effect, but how easy it is to grow. For example, if you live in a colder climate, having seeds suited for arid weather isn’t the best idea.

Your seed will germinate, but it may not last very long if it is not the right strain for your conditions and weather. Plus, such seeds are prone to genetic defects, diseases, stress, etc. 

How do you avoid this mistake?

By purchasing high-quality seeds from reputable breeders or seedbanks. Yes, they may cost a bit, but reputable seed banks always mention the primary phenotypes or traits of the strain and the kind of weather they grow best in. Reputable dealers also sell polished seeds with minimal chances of genetic defects while being resistant to diseases and stress factors. 

2. Using the Wrong Germination Method

Using the Wrong Germination Method

The second mistake may occur during the germination method when you don’t use the right method. This can lead to a poor, lanky seedling, or the seed may not sprout at all.

Ideally, cannabis seeds require the following conditions to sprout into healthy seedlings:

  • A dark, humid environment but not too humid 
  • Temperatures range between 70°F to 78°F (21°C to 25°C) with relative humidity between 70% to 80%
  • Adequate lighting, perhaps from a small fluorescent bulb or a window 
  • Careful handling of the seedling so it does not get contaminated or damaged 
  • Ph between 5.8 to 6.5 

When these conditions are not met, the seed may fail to sprout into a healthy plant. You can avoid this mistake by using the right germination process. These methods come in a variety, and you must choose one that fits your preferences and conditions. Here are the most common germination methods for cannabis seeds.

  • Paper Towel Method

The most common method for germinating cannabis seeds is to use paper towels. Here, you must place a sheet of paper towel on a pan or a tray, place your seeds on it, and cover them with another sheet of paper towel. Then, moisten the paper and let it sit for a few days. 

After a few days, the seeds will sprout into 2 to 3mm taproots, which you can then transfer into the growing container. 

  • Glass of Water 

Perhaps the easiest method to germinate cannabis seeds is to use the glass of water method, where you toss your seeds in a glass of lukewarm water. Wait for 24 hours and remove the seeds. Viable seeds would have already split their shells open slightly; however, even if they haven’t split open, it’s best to transfer them to paper towels for moisture. Remember, letting your seeds sit in water for more than 24 hours isn’t a good idea unless you’ve experimented several times before with success. 

  • Rockwool

Another common method, especially for hydroponic setups, is using Rockwool to germinate seeds. Here, you begin by soaking your Rockwool cubes in low-pH water for some time. Then, you place them on a tray, insert a seed in the hole of the cube, and wait for a few days.

Once the seeds have sprouted, you can transfer the Rockwool cube with the seedling into the growing medium of your choice. This method is easy and relatively safe since you don’t have to directly handle the seedlings — the Rockwool cube does it for you. 

  • Direct Germination

Lastly, for growers using soil as a medium, direct germination is more than enough. For this method, prepare your soil, poke a hole about a centimeter deep, and place your seed in it. Cover the hole and wait for a few days until the seedling appears. 

This method is easy and does not require any transplanting, so you can continue feeding the seedling until it turns into a mature plant ready for harvest. 

3. Using Unhealthy Soil 

Using Unhealthy Soil

If you are growing cannabis in soil, you must be meticulous about the soil you use. In this case, the most common mistake growers make is using reused potting soil, contaminated soil, or one devoid of nutrients. 

Here are some of the qualities of high-quality soil.

  • Nutrition

The soil must also be rich in nutrition, so you must use the right potting mixes or pre-fertilized soil. With nutrient-rich soil, you wouldn’t have to worry about administering nutrients to your plant until it enters the vegetative stage.

Nutrient-rich soil has enough nutrients to germinate and sustain a small seedling. 

  • Light and Airy

Healthy soil for cannabis cultivation should be light and airy. You can add perlite to the soil to increase drainage. When the soil is light and airy, it has adequate water retention and oxygenation but not so much that it drowns the roots (which can lead to root rot or other problems). At the same time, aeration will ensure roots have air to breathe. 

  • Contaminant Free

The soil must also be free of contaminants like pests, pathogens, bacteria, or fungi. Such contaminants may not be apparent in the beginning, but over time, they can multiply and damage your plant’s growth and lead to many other problems.

So, you must use high-quality soil purchased from reputable dealers. 

4. Using the Wrong-Sized Pots

Using the Wrong-Sized Pots

Apart from the soil, you must use the right container for your cannabis plants. It may not seem like a big deal, but you’d be surprised to know how much the container size can affect your cannabis plant’s growth. 

For instance, if the pot size is too small, it can hamper the root ball's growth, making your plant grow shorter than you’d expect. On the other hand, if the container is too big, a lot of the nutrients may not reach the roots, leading to nutrient deficiencies. 

The container size varies depending on the cannabis strain you are growing, the local environment, and your growth setup. So, be sure to do adequate research before choosing the container size. 

Along with the size, you also need to factor in the type of container you choose. Essentially, any type of container you choose must have drain holes at the bottom for the excess water to run out of. 

You can either choose traditional pots made of plastic or clay — these are cheap and good for beginners. However, if you want to take it one step further, you can choose fabric pots which are excellent for aeration and root development. 

5. Setting the Wrong Humidity Levels 

Setting the Wrong Humidity Levels 

Cannabis is sensitive to humidity; wrong humidity levels can significantly affect plant growth. Humidity makes transpiration possible for cannabis plants, allowing the plant to pull more nutrients from the soil easily. 

If the humidity is not ideal, the plant may fail to take up nutrients at the right rate, leading to slow growth and other problems. Additionally, high humidity is often a recipe for disaster for cannabis because it can lead to mold development or pest infestations. 

So, to set relative humidity at the right levels, you need to take some measures. For seedling cannabis, maintain an RH of 65% to 70%, enabling the seedling to consume more water and grow taller. 

During the vegetative stage, you need to gradually reduce the humidity from 70% to 40%. The plant is big enough to sustain itself, so it needs this level of humidity to acclimatize to the low humidity required for the flowering stage.

Once your plant starts flowering, you need to further reduce the humidity to around 30% if possible. Anything between 35-45% will be good at this stage. Dryer conditions will ensure the buds don’t get too moist and develop mold but do not reduce the humidity anymore as it can stress out your plant.

Remember to reduce the humidity gradually. Going from 70% to 40% instantly can cause a shock to your plant, and it may not be able to cope with it. Instead, reduce the humidity levels by 5% every week until you reach the desired levels. 

6. Overwatering 


A common mistake that many new growers make is feeding their cannabis plants more water than needed. This is an innocent mistake since many growers think more water leads to better growth. But overwatering often ends up doing more harm than good

There is a limit to how much water your plant consumes, so when you overwater it, the plant will not consume the excess water. Instead, the excess water will sit in the soil and suffocate the roots due to a lack of oxygen and slow down the plant's growth.

Additionally, soil that’s too wet can lead to mold development and slimy roots (or root rot), which are nasty problems that are difficult to fix and often end up killing the plant. 

So, look out for signs of overwatering. Some common symptoms are the soil being wet all the time, droopy or thick leaves that appear a little too shiny, etc. And to avoid this problem, only water your plant when the top inch of the soil is dry, and water it until at least 25% of the water drains out of the drain holes. 

7. Maintaining the Wrong pH Levels

Maintaining the Wrong pH Levels

Like humidity, pH is another factor that dictates how your plant consumes nutrients. The roots can only consume nutrients efficiently at some pH levels. If the pH is too low or high, the plant may fail to consume certain nutrients, leading to nutrient lockouts, deficiencies, or burns from excessive nutrients. 

pH refers to the alkalinity or acidity of the water (or the nutrient solution). For a healthy cannabis plant, you must maintain a pH level between 5.5 to 6.5 for hydroponic plants and 6 to 7 for soil-based cannabis. 

Here, it is essential that you invest in a pH meter to check the pH levels of your nutrient solution and the runoff water. The runoff water’s pH should be close to that of the solution — a sign that there is no salt buildup in the soil. 

If the two readings are drastically different, you must flush your plant to remove all the excess nutrients and recondition your nutrient solution.

On the flip side, if the pH of your nutrient solution is off, you can use pH up/down products. These products are easy to use and help you adjust the pH level of your solution with just a few drops. 

8. Ignoring Signs of Mold or Pest 

Ignoring Signs of Mold or Pest 

Mold and some pest infestations are notorious for ruining completely healthy cannabis plants in no time. And many growers often make a mistake in not identifying the symptoms soon enough. Often, when they do identify the problem, it is too late, and the plant is beyond recovery. 

Mold is one common culprit that occurs due to high humidity and unclean air. On the other hand, pests like spider mites, soft-bodied mites, thunder bugs, etc., multiply quickly and ruin your plant in a matter of days. 

So, you need to look out for the symptoms of both these problems. Check to see if your plant is experiencing mold infestations, slimy or dark roots (signs of root rot), white fuzzy growth on the plant or buds, a sweet smell in the buds, etc. 

If your plant suffers from mold, you can try natural remedies like neem, fish, sesame oils, or a mixture of water and baking soda. However, the results are not guaranteed. Mold is nasty, and getting rid of it is difficult. And if your cannabis buds have developed mold, unfortunately, nothing can be done about it — the best course of action is to toss the plant. 

Similarly, most pest infestations can be dealt with natural pesticides, the best of which is neem oil. Ensure you don’t spray the buds with it, though, as it can influence the flavor of the buds. 

Fortunately, there are many ways to prevent these problems. Keep your grow room well-ventilated with temperatures and humidity at ideal levels, and keep the air clean. And occasionally, look for any signs of mold or pests and eradicate them before they take over your plant. 

9. Boasting About Your Plant

Boasting About Your Plant

Most of the mistakes listed above will only cost you your cannabis plant, but there’s one mistake that can cost you a lot more is boasting about your plant to others, especially if you live in a country where cannabis is not yet legalized. 

Yes, you are proud of your plant and want to tell everyone about it, but you must curb your excitement and only reveal your secrets to those closest to you. But this isn’t only about you speaking about your plant; you must also not keep it out in the open where a passerby can see it. 

Even in places where cannabis is legalized, it is better to keep your cultivation hush-hush, lest you want your plant to get potentially stolen or invite unwanted attention. 

Here are some tips on how you can keep your cannabis plant discreet:

  • Grow your plant in a discreet location, away from the prying eyes of passersby and neighbors 
  • Grow tall, aromatic companion plants around your cannabis to hide it from view and cover the cannabis scent 
  • Use carbon filters or scrubbers to mask the smell of cannabis coming from your grow room 
  • If you are growing indoors, make sure you take the right steps to keep your grow room hidden 
  • When ordering seeds or any cannabis-specific products, always choose discreet shipping
  • When disposing of cannabis plant materials, put the pieces in a bag with food waste so it doesn’t stand out 

Keeping your cannabis plant discreet may seem tedious at first, but it can save you a lot of trouble — legal or otherwise. 

10. Harvesting at the Wrong Time 

Harvesting at the Wrong Time 

Even if you take all the right precautions during your plant’s growth, all your effort can mix in the dirt if you harvest your plant at the wrong time. You don’t want to harvest your plant too soon or too late — you must harvest it at the right time. 

How can you tell when it’s time to harvest? Look at the trichomes on the buds with a magnifying glass — they are the most reliable way to check your plant’s maturity. 

If all the trichomes are clear, it is too soon, and you need to wait a few more weeks, depending on your plant’s life cycle. Even when most trichomes have turned white or cloudy, you must wait — this is when the THC production in the trichomes is just beginning. 

The best time to harvest is when most trichomes have turned cloudy or white, and around 20% have turned amber. The perfect balance. But don’t wait beyond this point — if the majority of the trichomes turn amber, a lot of the THC will have degraded into CBN, and it won’t be as potent anymore. 

Another reliable way to know your plant’s maturity is the pistils. When these tiny hairs are white, the buds are immature. So, you must wait until 70% of them have turned orange or red. And if you want a more balanced high, you should wait until 90% of the pistils have turned amber or red. 

For best results, you should factor in both trichomes and pistils — you will find the sweet spot where the buds have peak THC levels. But you must also know your plant’s growth cycle and expected maturity time — you wouldn’t want to check the trichomes for the first time only to find them to have turned amber. 

Summary: 10 Mistakes to Avoid When Growing Cannabis

The ten mistakes listed above are only a few common mistakes you must avoid, but there are many more. These mistakes are easy to make but hard to fix, so it is best to avoid them in the first place. 

For many, the best way to learn is from making mistakes, but when it comes to cannabis, it is better to learn from mistakes others make and avoid them yourself. 

So, to summarize the article, pay attention to the strain you are growing, germinate the seeds well, use the right soil in the right container, set the right humidity, and water your plants well. Also, don’t forget to ignore any signs of pests or mold, and try keeping your plants discreet.

Follow the tips mentioned above, and you will end up with a large, healthy plant with many bushy nuggets of THC goodness. 


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30% humidity is desert climate, you would enter a very dangerous VPD zone at 23°C already. That's way too dry! Always go by VPD table! I never had budrot or any issues between 55% and 40%, and not every home grower owns a climate control device. Better get strains that keep up with your room climate, than to try and generate impossible environments. ✌️
@SlowpokeFuegobud,😍 so are you
@CannaScience, 💚 you da best!
@SlowpokeFuegobud, 40% seems like the ideal mark. I agree everyone doesn't have a device to control humidity, but if you can somehow get it to 30-40%, the flavors are better IMO. Added more info in the article :)
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