Many issues can arise when growing weed: discoloration of leaves is usually a sign of nutrient deficiency; tiny spots or webbing can mean a bug infestation; stunted growth can be a root problem.
What’s wrong with my weed plant?
Also, keep an eye on the pH of water you use on your weed plants. This overlooked aspect can quickly lead to big problems.
Too many nutrients
Similar to overwatering, beginning growers also have the tendency to give plants too many nutrients. A common misconception is that more nutrients equals bigger plants, so just keep adding more and more!
To increase the amount of light, you either need to get stronger grow lights (what grow lights work for growing cannabis?), or move your current grow light closer to your plants.
"Leggy" seedlings need more light
Get 2 x 40W 'daylight' CFLs (can support 1-4 seedlings)
These cannabis seedlings are growing tall and thin (and falling down) because they need more light.
Get 1-2 CFL bulbs and keep 2-3 inches away from the tops of your seedlings (be careful not to let seedlings grow into the light!)
Some growers bury the extra stem to make seedlings short again, which works, but as long as you start giving your seedling light it will do a "push up" and rise back up, strengthening its stem in the process! Here's what to do right away…
You can get more light later when the plant is making buds, but getting 2 CFLs should stop the stretching so you have a few more weeks.
Cannabis plants enjoy a warm sunny day. Not too dry, not too humid. Similar to humans, actually. Certain strains are more resistant to an extreme environment, but plants grow best in moderate humidity and warm-but-not-hot air. A good temperature range is warmer than 70°F (21°C) at night and around 79°F (26°C) during the day. Humidity around 50% is perfect.
1.) Grow Light
The most common cause of unhappy roots is overwatering, especially for seedlings and young plants. Overwatering is typically the result of giving too much water at a time, or watering too often.
3.) Unhappy Roots
If you’re struggling with high humidity, you may need to add an exhaust fan to vent out humid air and bring in fresh air. If your plants are in a grow tent, typically an exhaust fan that’s set up properly can keep the humidity just a little higher than in the room. If the humidity is much higher in the grow space than the surrounding room, that means you need to help equalize the air with an exhaust/intake fan, or by blowing the air around. If the humidity of your actual room is high, no amount of fans can fix that. In that case, you’ll need either a dehumidifier (raises temperature, lowers humidity) or an AC (lowers temperature and humidity) to bring the RH into a better range. Read the full humidity tutorial.