Growing cannabis is an art form that sits somewhere between gardening and chemistry. For many first-time growers, the journey begins with high hopes of massive yields and top-shelf potency, only to end in disappointment with stunted plants, yellowing leaves, or worse—a dead crop.
The truth is, cannabis is a resilient plant (it’s called “weed” for a reason), but it is also finicky about its environment. Small errors in the early stages can compound into harvest-ruining problems later on. The difference between “homegrown shwag” and dispensary-quality bud often comes down to avoiding a few specific pitfalls.
Whether you are growing in a high-tech indoor tent or a sunny spot in the backyard, here is a comprehensive guide to the most common mistakes when growing weed—and exactly how to fix them.
By far the most common mistake new growers make is overwatering. It stems from a good place: you want to nurture your plant. However, cannabis roots need oxygen just as much as they need water. When you keep the soil constantly saturated, the roots drown, rot, and cannot uptake nutrients.
It is easy to confuse overwatering with underwatering because the symptoms look surprisingly similar. In both cases, the plant droops.
Overwatered plants: The leaves look heavy, swollen, and curl downward (clawing). The drooping affects the entire leaf, not just the stem. The soil will feel wet and heavy.
Underwatered plants: The leaves look thin, papery, and lifeless. They droop because they have no internal pressure.
Stop watering on a schedule (e.g., “every two days”). Instead, water based on what the plant needs.
The Knuckle Test: Stick your finger into the soil up to your first knuckle. If it feels even slightly damp, do not water.
The Lift Test: This is the pro move. Pick up your pot when it is completely dry. Feel how light it is. Then, pick it up after a heavy watering. You should only water again when the pot feels light and airy, similar to its dry weight.
Use Fabric Pots: Plastic pots trap moisture. Fabric pots allow the sides of the root zone to breathe, making it much harder to overwater.
You can buy the most expensive nutrients on the market, but if your pH is off, your plant cannot eat them. This is a concept known as “nutrient lockout.”
Cannabis roots can only absorb minerals when the water/soil solution is within a specific pH range. If the pH drifts too high (alkaline) or too low (acidic), nutrients like iron, magnesium, and calcium precipitate out of the solution and become unavailable to the plant.
Many beginners pour tap water directly onto their plants without testing it. Most tap water is slightly alkaline (pH 7.0–8.0), whereas cannabis prefers slightly acidic conditions.
Soil pH: Aim for 6.0 – 7.0.
Hydro/Coco pH: Aim for 5.5 – 6.5.
Get a pH Pen: Do not rely on color-changing liquid drops if you can avoid it; they are hard to read. A digital pH pen is a cheap investment that saves crops. Always adjust the pH after you have added your nutrients to the water, as nutrients often lower the pH significantly.
Beginners often look at the feeding chart on a bottle of fertilizer and think, “If 5ml is good, 10ml must be better!” This is a recipe for disaster.
Cannabis plants—especially autoflowers—are sensitive to high levels of chemical salts. Overfeeding leads to “nutrient burn,” where the tips of the leaves turn yellow or brown and become crispy. If left unchecked, the leaves will curl up and die.
Start Low: Always start with 1/2 or even 1/4 of the recommended dose on the nutrient bottle. You can always add more, but you can’t take it out once it’s in the soil.
Read the Plant: Healthy cannabis leaves should be a vibrant, grassy green.
Deep/Dark Green: You are feeding too much Nitrogen (N).
Pale/Yellowing Green: You might need to increase the feed slightly.
The Flush: If you accidentally overfeed, “flush” the plant by watering it with 3x the volume of the pot using pH-balanced plain water to wash out the excess salts.
Light is the engine of plant growth, but it is easy to mismanage.
Too Close: This causes light burn. The leaves closest to the light will turn yellow or white (bleached) but the veins might stay green. Unlike nutrient burn, this only happens at the top of the plant.
Too Far: The plant will “stretch.” The stem becomes long, spindly, and weak as the plant desperately reaches for the light source. These plants often topple over under their own weight.
If you are growing photoperiod strains (plants that require 12 hours of darkness to flower), even a tiny pinhole of light during their “night” cycle can confuse them. This stress can cause the plant to reveg (stop flowering and go back to growing stems) or turn into a hermaphrodite (growing pollen sacs that seed your buds).
Hand Test: If you are using HPS lights, put your hand at the top of the plant canopy. If it’s too hot for your hand after 30 seconds, it’s too hot for your plants.
LED Specs: For LEDs, follow the manufacturer’s distance recommendations, which are usually 18–24 inches during vegetation and 12–18 inches during flowering.
Total Darkness: Sit in your grow room with the lights off. If you can see your hand in front of your face, you need to seal the leaks.
Cannabis enjoys a specific “Goldilocks” zone. Ignoring temperature and humidity is a common mistake that leads to mold, mildew, and slow growth.
You don’t need a degree in physics, but you should understand that temperature and humidity interact.
High Humidity + High Heat: Mold risk (Botrytis/Bud Rot).
Low Humidity + High Heat: The plant sweats (transpires) too fast and drinks too much water, potentially leading to nutrient burn.
Seedling Stage: They need high humidity (65-70%). Many beginners let the air get too dry, shriveling the baby plants.
Flowering Stage: They need low humidity (40-50%). Beginners often leave humidity high, which results in bud rot—a gray mold that eats your buds from the inside out just days before harvest.
Buy a cheap hygrometer (thermometer/humidity monitor). If you are growing indoors, an exhaust fan is non-negotiable to exchange stale, humid air for fresh air.
You have spent months watering and caring for your plant. The buds look big, they smell dank, and you are ready to chop. Stop!
Harvesting too early is the most heartbreaking mistake because it reduces both the potency (THC level) and the yield (weight). During the final two weeks, buds can swell by up to 25%. If you harvest when the pistils (hairs) are still white and sticking straight out, you will end up with “racy,” anxiety-inducing weed that shrinks to nothing when it dries.
Don’t look at the leaves; look at the trichomes (the crystal resin glands on the buds). You need a jeweler’s loupe or a cheap USB microscope.
Clear Trichomes: Not ready. Low potency.
Cloudy/Milky Trichomes: Peak THC. This is the standard harvest window.
Amber Trichomes: THC is degrading into CBN, which produces a “couch-lock” or sleepy high.
The Golden Rule: When you think it’s done, wait one more week.
Many growers start by finding a seed in a bag of weed they bought and planting it. While this is free, it is a massive gamble.
“Bag seed” often comes from a plant that was stressed and turned hermaphroditic (pollinated itself). The seeds it produces are genetically predisposed to doing the same thing. You might spend four months growing a plant only for it to fill with seeds or produce weak, airy buds.
Buy genetics from a reputable breeder. The cost of a seed ($10-$15) is tiny compared to the electricity and time you will spend growing it. Good genetics ensure disease resistance, higher yields, and predictable effects.
New growers often grab a bag of dense “garden soil” or “topsoil” from the hardware store. This soil is too compact for cannabis. It turns into mud when watered, choking the roots.
Cannabis needs a “light,” airy medium.
Soil Growers: Look for potting soil specifically mixed with perlite (the little white rocks). If your soil is dark and dense, mix in 30% perlite by volume to improve drainage.
Coco Coir: This is a popular alternative to soil made from coconut husks. It drains incredibly well but requires you to provide nutrients from day one.
Stagnant air is the enemy. Without a breeze, pockets of humidity build up around the leaves, inviting Powdery Mildew (white flour-looking spots on leaves). Furthermore, a gentle breeze strengthens the stems, allowing them to hold up heavy buds later.
You need two types of airflow:
Oscillating Fan: A clip-on fan inside the tent to move air around the leaves.
Exhaust Fan: An inline fan to pull old air out of the tent.
This isn’t a horticultural mistake, but it’s a critical one. The most common reason growers get ripped off or busted (even in legal states where they exceed plant counts) is because they told their friends.
Growing giant weed plants is exciting, and you will want to brag. Resist the urge. The rule of thumb in the grower community is: No smell, no tell, no sell.
If you can avoid these ten pitfalls, you are 90% of the way to a successful harvest. Here is your quick checklist to stay on track:
Watering: Lift the pot; if it’s heavy, don’t water.
pH: Keep water between 6.0 and 7.0 for soil.
Nutrients: Start with half strength; watch for burnt tips.
Lights: Check manufacturer distance; prevent light leaks.
Environment: High humidity for veg, low humidity for flower.
Harvest: Check trichomes, not hairs. Patience pays off.
Genetics: Buy quality seeds; avoid “bag seed.”
Soil: Ensure it has plenty of perlite for drainage.
Air: Keep the air moving with fans.
Security: Keep your operation to yourself.
Growing cannabis is a learning curve. You will likely make at least one of these mistakes on your first run, and that is okay. The best growers are simply the ones who killed the most plants and learned from it. Happy growing!
Learn how to cultivate marijuana. Find the best marijuana growing advice for seed germination, cloning, pruning, trimming, and curing to help maximize your yields.
$79.95
share this with your tribe
