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ideal temperature for cannabis

Ideal temperature for cannabis

Cannabis grows best when provided with ideal temperatures and humidity levels for each phase of growth. Staying within these limits is the challenge facing the summertime grower.

Summer is coming, and the lucky outdoor grower is stoked. Plenty of sun, wind, and even rain makes for superb cannabis. For the indoor grower, summer is a different story with its own unique set of challenges.

  1. First, you will need a hygrometer and a thermometer, or a combo unit. This way, you can maintain environmental conditions with complete accuracy. Advanced kits act as switches that run the complete environmental system automatically.
  2. Use exhausted light covers to control radiated heat from globes. This is a minimal investment, and should be considered when setting up a grow.
  3. Dimmable ballasts give you some control over the radiated heat from lights. Turning down the wattage during the hottest parts of the artificial day, but not interrupting the grow cycle, can cut heat output in half from the lights, and keep plants growing steadily.
  4. Make sure air circulation is thorough. Still air is the enemy of marijuana. Put pedestal fans and mount wall fans where they provide the best air movement around plants. Always have them set on oscillate.
  5. Opt for larger intake and exhaust fans. Larger fans running on a lower setting are more effective than small fans running on overdrive.

Cannabis grows best indoors under high-intensity discharge (HID) lights, which do their best to imitate the sun. The side effect of generating lots of lumens is heat. Most heat is created by light ballasts, but globes still emit enough heat to burn plants. Add to this some high summer temperatures, and environments can quickly become unsuitable for proper growth.
Increasing overall metabolism helps plants resist the effects of heat. Bigger, healthier, and more robust plants will tolerate environmental extremes better. When CO₂ density is increased to 1,200–1,500ppm, ideal gas exchange happens at 29°C.
Having complete control over the grow room environment will mean installing mechanical solutions. Initial outlay or price of upgrading will be offset by fat buds before summer ends.

  1. Grow at night. Make your day cycle during the night. Expect a 10–15°C difference in ambient air temperature at night.
  2. Bottles of frozen water, rather than ice cubes are a resource-friendly way to add cool to the room. A 2-litre bottle in front of a fan cools the airstream considerably, without adding moisture to the air. Ice cubes evaporate and increase humidity.
  3. Use insulation where practical. If building a grow room, insulate the complete structure well. Foam core panelling is quick and easy, is very soundproof, and also easy to clean. Flexible rolls of insulation can be used to drape over grow tents or pack around smaller spaces. Insulation also reduces the heat signature of clandestine grows in cannabis-unfriendly countries.

Before spending money on equipment, make sure your grow space optimises passive heat control measures. Providing the coolest ambient air temperatures is the first step in combating summer heat.

Growing in summer can be a challenge. Especially so for those grows closer to the equator. A common sense, passive setup with mechanical intervention when necessary makes summertime growing drama-free.

Marijuana grows best when it's kept within a particular temperature and humidity range. Here are the top tips for growing summer weed indoors.