There’s nothing more satisfying than growing your own cannabis – and in South Africa, it’s legal (Within certain limits) to do so privately, thanks to the 2018 Constitutional Court ruling. But before you break out the soil and seeds, it’s worth noting that growing weed of a high quality is not as simple as sticking a plant in the ground and waiting for the magic.
Many new growers (and even some experienced ones) fall into common traps that lead to weak yields, poor potency, pest infestations, or full-on plant disasters. Avoiding these pitfalls is crucial to growing weed right – so let’s steer you on your way to a successful harvest.
Growing Weed Mistake #1: Skipping the Research Phase
Top Mistake: Diving in without understanding cannabis biology or the basics of cultivation.
It might surprise you how many people buy a bag of seeds and some soil, plant the seed, and then lose faith when they don’t see a quality cannabis plant emerge. Growing weed gets easier the more you do it, sure – but if you’re starting out, it’s well worth your time and effort to look into the fundamentals of growing weed. Germination, planting, nutrients, watering – these are a must for every person who wants to start growing weed.
Why it matters: Cannabis is a complex plant with different growth phases, nutritional needs, and environmental requirements. Assuming it behaves like a tomato plant or a basil plant is a one-way ticket to a failed crop, so building a foundational understanding of how the cannabis plant works is crucial.
Top Tip: Start with foundational resources. Books like Marijuana Horticulture by Jorge Cervantes are widely respected by growers across the world for a reason – invest your time in reading and learning from a true master of the art of growing weed. Better yet, his recent book We Grow Cannabis is available for free download at Seedsman.com and will explain those basics of growing weed and a whole lot more.
And don’t forget the Seedsman blog – over the years, we’ve had some truly stellar cannabis cultivators write for us, and we’ve covered every practical aspect of growing weed in these very pages. Need to know something? Pop the term in the search bar and chances are you’ll find at least one article explaining it in useful detail.
Growing Weed Mistake #2: Using the Wrong Strain for Your Climate
Top mistake: Planting a strain that isn’t suited to your region’s environmental conditions.
Why it matters: Durban Poison thrives in KwaZulu-Natal's humid subtropical climate, but an indoor hybrid may flounder under those same conditions. Get it right, and you’re growing weed of the highest quality. Get it wrong, and you’re guaranteed lower yield and potency.
Top Tip: Know your region and know the strain. South Africa’s diverse climate means what works in Cape Town won’t necessarily succeed in Bloemfontein. Local landrace strains are often better adapted to South African weather and pests, having adapted to survive over generations – and they tend to to be more forgiving to beginners.
Further Reading:Growing Cannabis From Seed Outdoors In South Africa
Growing Weed Mistake #3: Overwatering (or Underwatering)
Top mistake: Loving your plant to death – or neglecting it completely - the drown vs drought scenario.
Why it matters: It’s an age-old problem for newcomers to growing plants of any kind – not just growing weed: How much should you water, and how often? Cannabis roots need both water and oxygen. Saturated soil leads to root rot; root rot leads to disaster. Parched soil leads to wilting plants, nutrient lockout, and, again, disaster. Knowing how and when to water your plants is essential to successfully growing weed, but it’s a fine balancing act – especially for outdoor growers in a hot climate.
Top Tips: Read and learn more about watering – our article, Watering Outdoor Cannabis Plants In South Africa is tailored to you, and will help you understand the nuances of watering in the South African climate. And if it all goes belly-up? Read our article on How To Fix Overwatering – ASAP, before it’s too late.
Follow the ‘lift the pot’ test (if you’re growing weed in a plant pot) - if the container feels light, it’s time to water. Check the soil by poking down 5cm or so – if it’s dry, it’s time to water. If you’re growing indoors, use well-draining soil and resist the temptation to water on a schedule – aim for an as-required basis instead. Cannabis is more drought-tolerant than many assume.
Growing Weed Mistake #4: Poor Lighting for Indoor Grows
Top mistake: Using cheap or inadequate lighting when growing weed, especially in winter.
Why it matters: Cannabis is a light-hungry plant. Poor lighting leads to leggy growth and reduced yields.
Top Tip: Invest in proper, full-spectrum LED grow lights. If you’re growing weed indoors this winter, remember that shorter daylight hours and chilly conditions make artifical light (and warmth) essential. Aim for 18 hours of light during the vegetative stage and 12 hours for flowering.
Bonus tip: Keep your light distance correct. Too far and plants stretch: too close and you risk light burn.
Further Reading:LED vs HPS LIghts: Which Are Best For Growing Cannabis?
Growing Weed Mistake #5: Ignoring Soil Quality and pH
Top mistake: Planting in garden soil without checking pH or nutrient levels.
Why it matters: Cannabis prefers slightly acidic soil (pH 6.0-6.8). Poor-quality or nutrient-deficient soil leads to stunted growth and weak buds – and if you’re growing weed, you’re likely growing to produce buds.
Top Tip: Use organic potting mixes specifically designed for cannabis or amend soil with compost, perlite, and worm castings. Always test pH with a meter – affordable kits are available online.
Further Reading:How To Measure pH Levels In Cannabis Soil
Growing Weed Mistake #6: Overfeeding Nutrients
Top mistake: Thinking more nutrients = bigger buds.
Why it matters: We get it – of all the rookie mistakes, this one kind of makes sense. After all, if you wanted to pack on size, you’d consume more calories, right? That may work for those who lift weights, but if you’re growing weed, it’s not the case. Overfeeding leads to burnt leaf tips, toxicity, and poor growth. Cannabis plants are sensitive and don’t appreciate being force-fed.
Top Tip: Start low, and go slow. Follow the manufacturer’s feeding schedule at half strength when in doubt. Organic growers should lean into compost teas, kelp meal, and other slow-release inputs – and remember – autoflowering cannabis needs less nutrients than photoperiod cannabis.
Growing Weed Mistake #7: Poor Ventilation and Airflow
Top Mistake: Growing in a closed space without airflow, or failing to address overly-bushy growth.
Why it matters: Stale air increases the risk of mold, especially during flowering. But rot (Botrytis) can ruin your entire harvest – just ask any Cape Town grower dealing with coastal humidity.
Top Tip: Use oscillating fans, vent your space, and learn the basics of defoliation by reading our guide. Ensure there’s a gentle breeze that makes your flowers dance – not too strong, but consistent. You need to have some air exchange around your plants when growing weed, or esle they could succumb to that dreaded mold.
Further Reading:How To Position Fans In A Cannabis Grow Tent
Growing Weed Mistake #8: Harvesting Too Early (or Too Late)
Top mistake: Picking your buds based on impatience rather than science.
Why it matters: If you’re growing weed, it’s surely worth the wait to ensure it’s fabulous, right? There’s a lot at stake here – harvest timing effects potency, flavor, and yield. Pick too early, and THC levels aren’t optimal. Too late and THC degrades into CBN, which creates more sedative effects. If you’re growing weed and your aim is couch-lock, that’s maybe not too big an issue – but if you’re growing a sativa for its uplifting or creative effects, it most definitely is.
Top Tip: Use a jeweler’s loupe, a magnifying glass, or even the zoom function on your phone camera to inspect the plant’s trichomes (those tiny, hair-like resin glands). They should appear milky white with some amber. If they’re clear, it’s too early. If they’re all amber, your buds are overripe. Follow visual cues, not calendar days.
Further Reading:How To Harvest Weed: A Guide For Growers
Growing Weed Mistake #9: Not Keeping a Grow Journal
Top mistake: Forgetting what you did last time – and repeating the same errors.
Why it matters: Keeping a journal when you grow weed lets you see what you did right – and what you did wrong. It’ll also let you look back and see what solutions worked and what didn’t. Cannabis grows over months. Without notes, it’s hard to track what worked and what didn’t.
Top Tip: Nobody likes homework, but log everything. Watering dates and quantities, feeding schedules, temperatures, strain genetics, even moon phases if you’re into biodynamic gardening. Not only does it help improve furture grows, but it also feels rewarding to reflect on your successes when growing weed. There’s hard data at the heart of success – so keep hard data.
Growing Weed Mistake #10: Ignoring Security and Privacy
Top Mistake: Letting your grow be visible or detectable.
Why it Matters: While growing weed is legal in South Africa for private use, public visibility (or strong odors drifting to neighbours) can attract attention – or thieves.
Top Tip: Keep your grow discreet, even though it’s legal. Use carbon filters indoors to limit aromas, and if growing outdoors, place plants in less-visible spots. In Cape Town, some growers joke that a strong wind isn’t the only thing that can carry your plants away - opportunistic ‘dagga dashers’ do exist!
Common Mistakes When Growing Weed - Forewarned is Forearmed
Growing weed at home isn’t just about getting high – it's about getting good at something, then getting better at it. Every grow teaches patience, attention to detail, and a deeper respect for nature, and every grow teaches you something new. It’s the same whether you’re growing weed on a windowsill as it is if you’re growing weed in a huge indoor tent – avoiding these 10 mistakes sets the foundation for healthier, more potent, higher-quality cannabis – and a more satisfying smoke.
