5 common cannabis growing mistakes and how to avoid them

Scientifically reviewed by Steven Philpott Jr

Mistakes don't mean you're a lousy cannabis grower - what matters is how you learn from the mistakes that (The Cannigma/Anthony Travagliante)

Growing award-winning cannabis doesn’t happen overnight. Even pro marijuana breeders experience their fair share of mistakes on the way towards mastery. Chances are, you’ll run into a few issues on your first couple of cultivation attempts. While this could be frustrating, remember these screw-ups are the “seeds” for future success—if you could learn not to repeat them, of course!

There are a few common mistakes that often crop up in novice growing circles. Learning about these errors ahead of time will put you on solid footing for your first foray into growing cannabis.

Error #1: drowning your plants with too much water

Watering a cannabis plant in an indoor grow tent — It’s easier to kill a cannabis plant from excess water than from a lack of it. (Shutterstock)

Novice cannabis growers have a heavy hand with water. Indeed, it’s virtually unheard of for first-time cultivators to “underwater” their plants. So, before you grab your water jug, you’ve got to exercise a lot of restraint.

Yes, cannabis roots need water at regular intervals, but they also need oxygen. If there’s too much water clogging up your soil, your roots won’t be well oxygenated, leading to stunted growth. ¹

How to avoid it

The standard technique for checking a plant’s water needs is to stick your finger in the soil. Only water your plants if your fingers feel dry.

However, for many new growers, it can be challenging to get the hang of this method. That’s why some cultivators recommend using a soil-water meter to gauge their soil’s moisture content. You could compare the readings on this device with how the soil feels to understand when to water your plants.

It’s also essential to double-check your pot’s drainage holes and tray. Always empty any sitting water, and be wary if it seems your soil is constantly soaked. If you know you have a habit of overwatering, forcefully stop pouring water more than you naturally would.

Error #2: overfeeding nutrients

Growing marijuana plants — There is such a thing as “too many nutrients,” and it can have disastrous consequences(The Cannigma / Anthony Travagliante)

Just like overwatering, too many new growers believe more nutrients will yield better results. Some novice cultivars also think too many nutrients can’t do any harm. What’s the big deal if a few extra nutes are floating in the soil? Cannabis just takes in what it needs, right?

In truth, there is such a thing as “too many nutrients,” and it can have disastrous consequences. Cultivators who overfeed weed could have to deal with a condition called “nutrient burn.” ²

When you have too many nutes in your grow medium, you will disrupt the delicate balance of chemicals that plants can absorb. This causes some nutrients to get “locked out” as they compete with other chemicals. If you’ve got nutrient burn, you’ll first notice the cannabis plant’s fan leaves turn brown at the tips and start to curl.

How to avoid it

To avoid nutrient burn, cut back your feeding schedule. In fact, many pro cultivators suggest starting with a third of the recommended dose of your vegetative or flowering nutrients. If you’re worried about nutrient deficiencies—and you’ve already double-checked the pH—you could increase this dosage to the manufacturer’s level.

True nutrient deficiencies are more common in hydroponics than soil. Since hydroponics run on water, there aren’t as many naturally-occurring minerals as in soil. Therefore, soil growers need to be extra careful about overfeeding their cannabis plants.

If you notice signs of nutrient burn, you’ve got to cut out the nutrients and flush your plants. After your plants seem to have recovered, you could add your nutrients back into your schedule. However, you should only add about a third or half the dose you previously gave your plants.

Error #3: not keeping an eye on pH

Cannabis plants growing — It’s important to constantly monitor the pH in your water and soil when growing cannabis (Shutterstock)

By contrast with watering and feeding nutrients, most new cultivators pay too little attention to pH levels. Short for “potential of hydrogen,” pH will give you a solid read on your water or soil’s acidity. While pH may not seem as consequential as water or nutrients, it’s a bigger deal than most first-time growers realize. ³

If your cannabis doesn’t have the ideal pH level, it cannot effectively absorb nutrients. So, even if you’re feeding your plants plenty of nitrogen , potassium , and phosphorus , they might not enter your plant’s roots. ⁴ ⁵ ⁶

Interestingly, many novice growers misdiagnose pH imbalances for “nutrient deficiencies.” In these cases, cultivators add way more nutrients than their plants need, which further compounds the problem.

How to avoid it

It’s important to constantly monitor the pH in your water and soil. Folks who are using soil should strive for a pH reading in the 6 – 7 range. By contrast, hydroponics growers need to keep their water more acidic at around 5.5 – 6.5. Whenever you notice your pH going slightly off, use a pH upper or downer according to the manufacturer’s recommendations. ⁷ ⁸

Ensuring your pH is in these ranges will eliminate the risk of misdiagnosing for deficiencies and nutrient burn.

Error #4: ignoring ventilation

grow weed plant — Correct air movement is essential for growing cannabis successfully (Shutterstock)

Air movement is essential for marijuana. Sure, many cannabis strains evolved in hot and humid regions, but that doesn’t mean extreme humidity equates to good buds. New growers often underestimate how many benefits a comprehensive ventilation system has for cannabis plants.

How to avoid it

First and foremost, proper ventilation decreases the risk of mold and pest infestations. An oscillating fan will also provide gentle friction, which will help develop stronger stems. Bulking up your branches during vegetation will make it easier for plants to carry heavy buds during flowering.

As a bonus, people who use a carbon-air filter will reduce skunky aromas getting into the air. Anyone who places a high priority on secrecy must invest in one of these odor-absorbing filters.

It’s well worth the effort to plan a thorough ventilation system beforehand. Adding an exhaust, carbon-air filter, and oscillating fan will decrease the risk of illness and improve the overall quality of your buds.

Error #5: harvesting buds way too early

Harvested cannabis — If you harvest your buds too early, they might not achieve the potency you’re looking for (The Cannigma / Anthony Travagliante)

The temptation to harvest too early is far more common amongst newbies than harvesting too late. Staring at those juicy buds day in and day out can feel torturous, but patience is crucial when deciding when to break out your scissors.

If you harvest your buds too early, they might not achieve the potency you’re looking for. Whether you’re growing CBD or THC-heavy flowers, you need to wait for most of the trichomes to switch from clear to white. If you could see through most of the trichomes, that means they don’t have high cannabinoid concentrations.

How to avoid it

The best way to making sure you harvest at the right time is to use a 30x jeweler’s loupe before you start growing. This tool will come in handy as you scan your plant’s buds for trichome colors.

Interestingly, most cannabis cultivators would prefer harvesting slightly late than too soon. Although late buds may have more CBN than THC, they tend to have higher concentrations of cannabinoids versus early nugs. Keep this in mind when you’re scanning your buds during late flowering.

Mistakes can make you a better bud breeder

Mistakes don’t mean you’re a lousy marijuana grower; what truly counts is how you move forward after messing up.

Luckily for 21st-century cultivators, there are now dozens of reputable grow forums where you could learn everything about growing cannabis. So, if you’re ever running into issues, it’s a good idea to join a few chat groups and search for your problem.

As the stigma surrounding cannabis cultivation goes away, it should get even easier for marijuana growers to share their expertise.

Sources

Ben-Noah, I. and Friedman, S.P. (2018), Review and Evaluation of Root Respiration and of Natural and Agricultural Processes of Soil Aeration. Vadose Zone Journal, 17: 1-47 170119. https://doi.org/10.2136/vzj2017.06.0119
Cockson, P., Landis, H., Smith, T., Hicks, K., & Whipker, B. E. (2019). Characterization of Nutrient Disorders of Cannabis sativa. Applied Sciences, 20, 4432. https://doi.org/10.3390/app9204432
Neina, D. (2019). The Role of Soil pH in Plant Nutrition and Soil Remediation. Applied and Environmental Soil Science, 1–9. https://doi.org/10.1155/2019/5794869
Saloner A, Bernstein N. Response of Medical Cannabis (Cannabis sativa L.) to Nitrogen Supply Under Long Photoperiod. Front Plant Sci. 2020;11:572293. Published 2020 Nov 17. doi:10.3389/fpls.2020.572293
Bevan, L.; Jones, M.; Zheng, Y. Optimization of N, P, K for Soilless Production of Cannabis sativa in the Flowering Stage Using Response Surface Analysis. Preprints 2021, 2021080460 (doi: 10.20944/preprints202108.0460.v1
Shiponi S, Bernstein N. The Highs and Lows of P Supply in Medical Cannabis: Effects on Cannabinoids, the Ionome, and Morpho-Physiology. Front Plant Sci. 2021;12:657323. Published 2021 Jul 15. doi:10.3389/fpls.2021.657323
Gentili R, Ambrosini R, Montagnani C, Caronni S and Citterio S (2018) Effect of Soil pH on the Growth, Reproductive Investment and Pollen Allergenicity of Ambrosia artemisiifolia L. Front. Plant Sci. 9:1335. doi: 10.3389/fpls.2018.01335
Gillespie, Daniel & Kubota, Chieri & Miller, Sally. (2020). Effects of Low pH of Hydroponic Nutrient Solution on Plant Growth, Nutrient Uptake, and Root Rot Disease Incidence of Basil (Ocimum basilicum L.). HortScience. 55. 1-8. 10.21273/HORTSCI14986-20.