How best to water cannabis
One of the most common mistakes novice growers make is over-watering their crops. Warning signs to look out for if you are over-watering include yellowing leaves and slow growth. To determine whether a plant needs watering, it is better to lift the pot and gauge its weight. You will soon become accustomed to judging whether or not the plant requires water. Check the pH of your water using an inexpensive aquarium test kit. Some plant feeds are specifically designed in hard or soft water areas. One way to determine if your water is hard is to check how it lathers with soap; hard water will have difficulty lathering. In comparison, soft water will lather quickly. Rainwater is acceptable to use.
Cannabis needs air and carbon dioxide
Indoor gardens require that the air temperature be maintained within the ideal range and recirculated. HID lights emit heat so an air extraction system needs to be fitted. You can purchase an “inline” four-inch fan online. This should vent out of the grow space with ducting, and is better purified through a carbon filter to eliminate any pungent odors. However, this depends on your situation and is not always necessary. Air circulation is best provided using office desk fans blowing over the crop. Carbon dioxide (CO2) needs to be supplied to the plants so a passive vent (open but with no fan drawing air in) needs to be fitted. There is no requirement to add additional carbon dioxide using CO2 cylinders. Ensure that your extraction system draws in a good supply of fresh air from the outside.