4 Weed Plant Stages: Germination, Seedling, Vegetative, Bloom - Happy Hydro

From seed to harvest, the cannabis plant grows through four stages of life: germination, seedling, vegetative, and bloom. Each stage requires subtle adjustments in temperature, humidity, light, and more.

Do you know the specific care instructions for each of the four weed plant stages of life? Let's get into the details about what conditions help the plant thrive during each stage (and how long it takes).

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Germination Stage

If you are growing cannabis from seeds, you need to trigger germination with the right conditions. Cannabis seed germination doesn't require light, but it does need a warm and wet environment to encourage the sprout to crack from the seed. You'll also need to ensure it doesn't dry out afterward.

Many growers start germination using the paper-towel method (outlined here). Seeds folded within a damp paper towel and tucked into a zip lock bag works for all types of seeds, including weed seeds.

Seeds, especially weed seeds, require warm temperatures to encourage germination. Use a heat mat or a warm area of your house to reach 70 to 90°F (21 to 32°C). When the conditions are right, and the seeds are viable, they should sprout within four to seven days. 

  • Time to Germinate: 4 to 10 days
  • Temperature: 70 to 90°F (21 to 32°C)
  • Humidity: 80-95%
  • Lighting Requirements: None during germination

Seedling Stage

The seedling stage of cannabis cultivation is from the time the seed sprouts to when it develops full fan leaves.  A mature fan leaf has five to seven different blades. Small seedlings will begin with a single blade, slowly putting out leaves with more and more until maturity.

Seedlings are delicate and require careful handling. They can't handle dramatic changes to their environment and are super susceptible to disease and pests. Make sure to keep a clean grow room and monitor daily for signs of stress. 

Keep the seedling environment's temperature between 68 to 77°F (20 to 25°C) and the relative humidity at 60 percent to start. Slowly reduce the humidity throughout the seedling stage until between 40 to 50 percent. Cannabis seedlings also like a lot of light, up to 24 hours of sunlight a day. However, some choose to keep the light schedule at 18 hours a day.

  • Time in Seedling: 2 to 4 weeks
  • Temperature: 68 to 77°F (20 to 25°C)
  • Humidity: 60 to 70% 
  • Lighting Requirements: 18 or more hours a day

Vegetative (or Veg) Stage 

Vegging is when a plant puts all of its resources into leaf production. It's bulking up its tiny energy factories (leaves) to be able to feed the flowers when the time is right. 

Vegging lasts anywhere from three weeks to 12. As soon as the plant reaches the size and maturity you are looking for, adjust the light schedule to trigger flower development. 

Shorter periods are for growers looking to produce small plants (suitable for tiny grow spaces), while longer would produce larger plants. Indoor growers have total control over how long their plants are in veg because it's based on the light schedule. 

During the veg weed plant stage, it requires 16 hours of light a day (or more). This not only helps the plant bush out, but it also helps stimulate root growth. Better root development means more nutrient supply and an overall healthier plant.

During veg, keep the indoor environment a consistent 71 to 82°F (22 to 28°C ) and slightly cooler at night. Humidity-wise, you can technically increase it to up to 70 percent. Although to reduce the risk of mold and mildew, around 50 is usually recommended. 

  • Time in Seedling: 3 to 12 weeks
  • Temperature: 71 to 82°F (22 to 28°C )
  • Humidity: 50% to 70%
  • Lighting Requirements: 16 or more hours a day

Flowering (or Bloom) Stage

The final and most exciting time for cannabis cultivators is during the bloom stage. This is when a plant transitions from producing only leaves to producing flowers.

Cannabis in bloom requires lower humidity and temperatures than cannabis in veg. This replicates the natural transition from summer to fall-time climates.

Keep humidity under 50 percent. The higher the humidity during this period, the higher the risk of bud rot. While the lights are on, temperatures between 70 to 85 °F (20 to 30 °C) are perfect. Again, aim for a few degrees cooler at night.

Going into flower also means adjusting the slight schedule to an even split: 12 hours on and 12 hours off. Unless you have an autoflowering variety, this is critical to trigger bloom.

The strain you grow will ultimately determine how long your plants flower for, although between eight to 12 is a safe bet. Use a LED Loupe Light to inspect later-stage flowers to see if it's nearly harvest time.

  • Time in Flower: 8 to 12 weeks
  • Temperature: 70–85 °F (20–30 °C)
  • Humidity: 40 to 50 percent
  • Lighting Requirements:  12 hours a day

Slight Adjustments For Each of The Weed Plant Stages of Life

In cannabis cultivation, the biggest yields are from making small environmental adjustments during each phase. The requirements in the seedling stage are much different than those in flower.

As your babies grow, adjust the indoor grow environment to support the healthiest development. That means vigorous germination, prolific leaves and roots in veg, and big beautiful buds in flower.

Author | Chris McDonald

With two decades of expertise, Chris leads Happy Hydro in redefining sustainable gardening and delights in backpacking adventures, mind-expanding journeys, and creating memories with his loved ones.

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