Cannabis cultivation is a rewarding, fun pastime. Every so often, though, nature and bad luck can disrupt growing activities. Though we cannot cure everything, the knowledge in this guide will help you identify and avoid some of the most common problems found in marijuana grow ops across America, from Oregon to Ohio.
Nutrient and pH Imbalances
Imbalances and fluctuations in soil or feed pH can be disastrous for cannabis seed growers. However, this problem is one of the easiest to point out and to resolve. Hydro and coco growing media should be at a pH between 5.5 and 6.5. Soil is a bit more forgiving, and because it acts as a buffer, it can have a pH of up to 7.5. Each strain has a fertilizer preference and a pH sweet spot, and only hands-on experience and time will help you find it.
As the plants grow, imbalances from the usage of poor-quality nutrients and over-feeding can spell trouble. When cannabis plants have wilted, discolored, and burned leaves, it is typically due to nutrient lockout or nutrient burn. In either case, the pH is unbalanced, and a pure water flush may help solve the problem.
After a flush, you will have to evaluate multiple factors when identifying and treating the problem. Testing water runoff with a pH tester will offer some clues, as will a visual inspection of the plants. Using pH-balanced nutrients is an easy and efficient way to prevent these problems in the future.
Overwatering and Underwatering
Sickly, droopy plants may suffer from under- or overwatering. In both cases, the plants’ roots are suffering, and their growth will stop. Until countermeasures are implemented, plants will deteriorate and become more vulnerable to disease and pest infestation. It is possible to determine the nature of the problem by evaluating the growth medium and evaluating the plants’ watering schedule.
When growing in standalone containers, the easiest way to gauge the need for water is to lift the pot. If the pot feels light, the plant may need water; if it feels waterlogged, it is okay to wait. Hydroponics setups are more susceptible to under- and overwatering. Be sure timers are properly set and keep an eye on water pH and plant behavior. Underwatered plants are droopy, with yellow sagging leaves and a dry growth medium. Though overwatered plants may look similar, the medium will be wet, and the roots may give off a foul odor.
Of all the problems in this guide, over- and underwatering are the easiest to correct. Try to adhere to a feeding and watering schedule and monitor water runoff and plant behavior when setting up a wet/dry cycle.
Heat Stress
Whether growing indoors or outside, heat stress will look the same. Leaves on your 420 plants or 710 plants will look yellow, brown, and burned. Indoor growers can simply change positions of grow lamps and other environmental controls. However, keeping the canopy in the right place is crucial. A simple rule is to put a hand near the plant canopy; if it is too hot, your plants will be uncomfortable as well.
Outdoor heat stresses are harder to control but increasing watering and shading the plants may help. With some gardening shade fabric, it is possible to filter out the sun’s most intense rays. By planting seeds at the right time, you may be able to avoid the worst of the heat stress.
Common Pathogens and Pests
Like other gardens, cannabis crops are susceptible to pest infestation and disease. Here are some of the most common pests and pathogens growers encounter.
- Spider mites: These are primarily indoor pests, and just a few can ruin an entire crop. They are only visible when in clusters, and they should be eliminated immediately with a special spray during the vegetative stage.
- Mold and fungi: The easiest way to manage bad fungi is to add good ones. For instance, Mycorrhizae can be added to coco or soil. Hydroponic growers should use specialized nutrients and avoid thick organic solutions. Indoor grow ops should have adequate airflow, and outdoor crops should be planted in a greenhouse or at the correct time. When the grow op is well managed, mold and fungi will not be a problem.
- Pets: It is crucial to keep household pets out of the grow room, even if they are well-behaved. Outdoor plots should be fenced in. Rodent infestations can be avoided with basic cleanliness and the usage of humane traps. However, if these pests are a serious issue, choose a new growing spot.
Nutrient Burn
When cannabis plants receive too much potassium, phosphorus, and nitrogen, a condition known as nutrient burn is said to occur. Cannabis plants need nutrients to grow, but too much of a good thing can be a bad thing. Nutrient burn may show on just a few leaves or an entire plant.
Working against such issues depends on their nature and severity. Check mineral levels in hydro or soil systems with a ppm meter; during the flowering stage, 1050ppm is ideal. If the soil contains an extremely high nutrient level, flush it with distilled or pH-adjusted water.
When setting up a grow op, do not buy soil with a high fertilizer content. Use clean water for plants, as tap water may contain too many minerals. Though cannabis-specific nutrients are best, formulas for tomatoes will also work. As a rule, begin with ¼ of the manufacturer’s lowest suggested dose of any nutrient.
Nutrient Lockout
This problem occurs when marijuana plants are not absorbing nutrients in the growth medium. When nutrient and pH levels are not optimized, nutrient lockout is more likely to occur. If it is not immediately resolved, the plants may die rather quickly.
Nutrient lockout symptoms closely mimic those of a deficiency. Plants will begin to look flimsy, with curled, yellow, and weak leaves. The simplest way to identify the issue is to check the growth medium’s pH level. Soil-based systems should be at 6.0-7.0, while hydroponic systems should be kept at 5.5-6.5. When this problem arises, it is also important to determine which nutrient is locking the others out. Consider flushing the plants and practicing better nutrient management.
Light Burn
Just like humans, cannabis plants should not be left to bake in intense heat and light. Indoor gardens are highly susceptible to light burn, which happens when plants are placed too close to powerful grow lights. Heat stress and light burn typically go hand in hand.
Symptoms of light burn usually appear on plant tops, as leaves become brown, yellow, or spotted. The leaves’ middle veins may stay green, as light burn gradually moves inward. Light burn does not occur in outdoor gardens because sunlight works differently. However, when THC or CBD cannabis plants are moved outdoors after living under artificial lighting, they may exhibit signs of light burn.
When fighting light burn, light intensity and heat are two of the most important considerations. If buds and leaves exhibit trouble signs, simply move the lights away or replace bulbs with less potent ones. Indoor gardens should be kept at about 77 degrees Fahrenheit with plenty of air circulation.
Growers should regularly check the buds and leaves closest to the grow lights. Buying weaker lights for use during the flowering stage is a good choice because that’s when light burn usually occurs. Ensuring proper air circulation and grow room temperature is another smart move.
Wind Burn
Just as we do, cannabis plants like the occasional cool breeze. However, if winds get a little too intense, the plants will show signs of stress which are known as windburn. This is a common problem in indoor grows where space limitations place fans in unnatural positions. The issue is rare outside because wind patterns eventually stabilize.
Windburn is an easy issue to identify because of the inner workings of an indoor grow op. If plant leaves close to the fan develop droopy, curly claws, windburn is likely to blame. Additionally, when fans are pointed right at plants, or when leaves are flapping vigorously, airflow may be too strong.
The simplest way to fight windburn is to position fans well and to use the right settings. Because cannabis branches and stems are strengthened by gradual airflow, leaves and plants should move gently rather than quickly. Air from fans should be directed between the canopy and the grow lights, and the fan itself should oscillate. Some growers have seen success when placing a small fan that generates a gentle vertical breeze.
To minimize the risk of windburn, plan the grow operation before planting the seeds. Windburn typically occurs when a grower tries to put too many cannabis plants into an indoor grow room. Plants need room to breathe and grow and overpacking the grow room will not increase crop yields; it just causes windburn and other problems. Consider adding fans with multiple settings so they can be tailored to the grow op or direct the fan toward a wall, so the plants are not exposed to direct winds.
It is worth a quick mention here that although autoflowering seeds make many areas of growing more simplified, they are not immune to the wind or any of the other plant stresses mentioned above.
In Closing
A successful cannabis growing operation requires attention to detail and monitoring for certain conditions. By looking for the signs of windburn, pest infestation, heat stress, and the other problems we have mentioned here, you will ensure the quality and consistency of the crop whether your plants are growing in Louisiana, Nevada, or Illinois.
