Learning how to care for your cannabis plants can be simple. Once you understand the ideal growing environment for cannabis to thrive. So, let’s dive right into it.
Temperature & Humidity
Temperature and humidity play a huge role in how to care for your cannabis plants. So, it’s important to stay within the ranges for each stage of life. Now that you have successfully germinated your seeds, it’s time to care for the resulting seedlings that sprouted. At the beginning of their life, seedlings need to be checked on regularly and prefer the warmer more humid end of the ideal ranges for vegetation. If this is your first or second grow, this is especially important. The first few weeks are crucial as the plant is very sensitive to its environment. Also, their size makes them more vulnerable to problems. You’ll want to take the first week to try to fine tune your environment so that it is consistent and in the ideal ranges. This will produce the best results.
Temperature
The ideal temperature ranges change throughout the life cycle of the cannabis plant. They like it to be warmer when they’re seedlings and as they get older, they need less warm temperatures. Then in flower, keeping it lower is better to preserve the terpenes. Keeping temperatures in check can be difficult if you have a hot grow light. This is where proper air circulation and exhaustion come in handy. I’ll cover that in the Air Circulation section.
Ideal Temperatures:
- Seedling/Vegetative Stage – 70°-85°F/20°-30°C
- Flowering Stage – 65°-80°F/18°-26°C
- Late Flower – Avoid going above 80°F/26°C as this can burn off terpenes
- For both vegetation and flower, night time/lights off should be between 5-10° cooler
Once your plant starts showing sex; either female pistils or the male pollen sacs. You can remove the males and start flowering your female plant(s). If it’s a photoperiod plant, you do this by changing the light cycle from 18-6/20-4/24 to 12/12. If you’re growing an autoflowering strain, it will automatically start to flower without any changes to the light schedule.
Humidity
Humidity needs change throughout the life cycles of the plant. They tend to like it more humid when they’re just starting out. You can slowly reduce the humidity by about 5% each week until you reach 40%. It’s easier to achieve higher humidity once there’s some vegetation on the plant. In flowering, you want to keep the humidity lower, especially on the final weeks. This helps to decrease chances of bud rot and is said to increase trichome production. Flowering plants prefer lower humidity. During late flower, you can use a dehumidifier to lower the humidity as low as you can to cause a stress response by the plant in the form of more trichomes/resin production.
Ideal Humidity:
- Seedling Stage – ~70% RH, you can slowly reduce this by about 5% per week until you reach 40%
- Vegetative Stage – 40-60% RH
- Flowering Stage – 40-50% RH
- Late Flower – <40% RH
Light
You want to provide your plants with an adequate amount of light so that they can thrive. The amount of light the plants receive directly affects your yields. If you use less light, your yields will be limited. The best way to figure out how many watts you need is by first figuring out your canopy’s square footage. For this equation, you need to use the square footage of the canopy and not the entire tent/grow space. Then, you need about 50 to 75 watts per square foot.
I aim to give each plant between 50-100 true watts. You can use more watts than this but this is the minimum for good results. By providing your plants with proper lighting, they can flourish and grow quickly. You don’t need to spend a fortune to get adequate light for your plants either.
Light Cycles & Light Spectrum
During vegetation, you want to have more light then darkness. The exact cycle is up to you. You can choose 18 hours of light with 6 hours of darkness, 20 hours light with 4 hours of darkness or 24 hours of straight light. For photoperiod plants, you need to change the light cycle to trigger the budding process. Changing the cycle to 12 hours of light and 12 hours of darkness will start flowering the plant.
Light spectrum can also affect the way your plant grows. The more blue spectrum will result in taller and less bushy plants. While a more red spectrum will result in shorter and bushy plants. Full spectrum LED lights take advantage of the light spectrums and give the plants optimal colours for different stages of growth. This helps plants to grow as fast and healthy as possible. For HID lights, the metal halide bulb is in the blue spectrum and is best suited for vegetation. While the high pressure sodium bulb falls into the red spectrum and is better suited for flower. Although, a high pressure sodium can be used through an entire grow.
pH Levels
Ph levels are an important part of the puzzle. In fact, it can be a huge factor in how to care for your cannabis plants. So, you’ll want to keep your pH within the proper range for the entire grow. With slight variations (0.1-0.2 differences) in the exact pH, this allows different nutrients to absorb more efficiently.
You can use pH up or pH down solutions to pH balance your water. You can also use lemon juice as a natural pH down, but if you do, a little goes a long way. I add about 2 ml of lemon juice to 1 gallon of water. This amount of lemon juice is dependent on the starting pH value of the water. My water starts at about 7.0. And again, pH ranges depend on the medium you are using. I use soil and aim to have my water at a pH of about 6.5. This allows all of the nutrients to be able to be absorbed purposely.
Ph ranges for optimal nutrient absorption:
- Soil – 6.0-7.0 (Aim for 6.5)
- Coco coir/Soilless medium/Hydroponics – 5.5-6.5 (Aim for 6.0)
The Importance of pH Levels When Growing Cannabis
Watering Your Plants
When seedlings first sprout, you only need to water a small circle around the plant. If you saturate the entire pot of medium, you increase your chances of over-watering your seedling. As your plant grows bigger, you can increase the size of the watering circle. Once the plant is about 8 inches to a foot high, you can start to water the entire pot when you water the plant. From that point on, you can saturate the entire medium in the pot. As plants get bigger, their thirst for water increases as well. Always monitor the top inch or so of medium to see if your plant needs water. This is especially important as the plants get bigger.
If your temperature and humidity are within the ideal range, try to water your plants every other day. Make sure to monitor the plant after you water it so you can see any signs of under or over-watering. They can both have similar symptoms but you should be able to tell the difference based on the medium. If it’s usually moist, it’s probably over-saturated with water. If your medium is usually dry, it’s more than likely under-watered. The key to watering your plants is to saturate the medium around your plant and let the top of the medium dry out before watering again. Mastering how to care for your cannabis plants is largely impacted by your watering habits. If too dry or too wet, it can effect the plants growth.
How to Water Your Cannabis Plants
Air Circulation
Proper air circulation is essential for growing cannabis. It can help prevent pests and problems by preventing their ideal conditions. Once your seedling sprouts and looks healthy and strong, you can start using a fan to create a light breeze. This not only moves the air around the grow area but also strengthens the plants stem. Once the plant gets bigger, you can increase the fan speed. You should also have 1-2 fans (oscillating or not) in the grow room. One that is under or at canopy level and one that is at the top of the canopy or slightly above it.
Unless you’re growing in an open space, it’s a good idea to use an intake fan & an exhaust fan system to replace the warmer air with fresh, cooler air. This also gives your plants a steady supply of CO2 from the fresh air. If you have a hot grow light such as a High Pressure Sodium light, you’ll need to have an exhaust fan system to reduce the temperature. Giving your plants proper air circulation has amazing benefits to your grow. It can even help your buds fatten up. Cannabis plants are wind pollinated, so the more wind, the more they put out bigger buds to get pollinated.
CO²
If you’re growing in a tent, you may want to use supplemental CO2 to supply your plants with constant carbon dioxide. This is essential in the photosynthesis process. There are both pre-made products you can purchase or DIY recipes to make your own. If you use these, you will need to keep temperatures a little higher. I have no experience using these yet but I may try it out in the future.
Transplanting Your Cannabis Plants
When growing photoperiod plants, you’ll need to transplant them as they outgrow their pots. You don’t want the plants to get root bound. It can inhibit growth. Luckily, The process of transplanting is very simple.
- Prep the bigger pot by filling it up most of the way (be sure to leave enough room to bury the transplanted plant and cover it with fresh medium)
- Then, carefully hold the plant at the stem and turn the pot upside down
- Gently move the pot until its loose and pull the pot off of the medium and roots
- Then, place the plants roots into the bigger pot, making sure that the roots have enough room to be completely covered by new medium
- Cover the plants roots with fresh medium and gently pack the plant down once the bigger pot is filled
- You can now give the plant some water and you’re done