The Complete Guide to the Growth Cycle of Auto-Flowering Cannabis Plants

Growth Cycle of Auto-Flowering Cannabis Plants

Growing auto-flowering cannabis plants can be incredibly rewarding. These plants offer a faster route to harvest compared to photoperiod strains, making them perfect for growers seeking efficiency. Understanding each stage of their growth cycle is essential for ensuring healthy development and a bountiful yield. Let’s dive into the journey from seedling to harvest, and I’ll share some practical tips along the way.

Seedling Stage (0-2 weeks)

The journey starts in the seedling stage, lasting from 0 to 2 weeks. This period is crucial as the plant establishes its roots and first leaves.

Lighting: Provide 18-24 hours of light per day. Young seedlings thrive under continuous light, supporting rapid growth and strong root development.


  • High Humidity: Seedlings love a humid environment. Aim for around 60-70% humidity to prevent drying out.
  • Gentle Watering: Be careful with watering. The soil should be moist but not waterlogged. Overwatering can lead to root rot, while underwatering can stunt growth.

I remember my first time growing auto-flowering cannabis. I was so anxious about getting the watering just right. It took a bit of trial and error, but I found a balance that worked for my plants.

Vegetative Stage (3-4 weeks)

During the vegetative stage, your plants will start to grow rapidly, developing sturdy stems and lush foliage.

Lighting: Continue providing 18-24 hours of light per day. Auto-flowering strains benefit from long light periods without needing a change in the light cycle.


  • Rapid Growth: This is a period of vigorous growth. Ensure your plants have enough space to expand and thrive.
  • Nutrient Needs: Increase the nutrient levels to support this growth spurt. Use a balanced fertiliser with higher nitrogen content to promote healthy leaf and stem development.

Pre-Flowering Stage (5-6 weeks)

As your plants enter the pre-flowering stage, they will begin to show the first signs of budding.

Lighting: Maintain 18-24 hours of light per day. Consistent lighting helps auto-flowering plants transition smoothly to flowering.


  • Signs of Flowering: Look for pre-flowers at the nodes, where the branches meet the stem. This indicates the plant is preparing to bloom.
  • Bloom Nutrients: Consider switching to bloom nutrients, which have higher phosphorus and potassium levels to support flower development.

Flowering Stage (7-10 weeks)

The flowering stage is where your hard work begins to pay off, as buds start to form and mature.

Lighting: Keep providing 18-24 hours of light per day. Auto-flowering plants don’t require a change in light cycle to flower, making this stage easier to manage.


  • Bloom Nutrients: Continue using bloom nutrients to enhance bud production and quality.
  • Reduce Humidity: Lower the humidity to around 40-50% to prevent mould and mildew, which can damage your buds.

Harvest (10-12 weeks)

The final stage of the growth cycle is harvest time, a critical period where timing is everything.

Lighting: Maintain the light schedule until the harvest. Consistent lighting ensures the plants stay healthy until the end.


  • Monitor Trichomes: Check the trichomes on your buds with a magnifying glass or microscope. Harvest when they are mostly milky white with some turning amber for the best potency and flavour.
  • Preparation: Prepare your drying area to ensure a smooth transition from harvest to curing.

Additional Tips for Growing Auto-Flowering Cannabis

  • No Light Cycle Change Needed: Unlike photoperiod strains, auto-flowering plants do not need a change in light cycle to trigger flowering. This makes them more straightforward for beginners and those with limited growing space.
  • Consistent Environment: Maintain stable temperature and humidity levels throughout the growth cycle. Sudden changes can stress the plants and affect their development.
  • Responsive Adjustments: Pay close attention to how your plants respond to their environment. Adjust nutrient levels and other conditions as needed to keep them thriving.

By following these guidelines, you can ensure a healthy growth cycle for your auto-flowering cannabis plants. Adjust nutrient levels and environmental conditions based on the specific needs of your plants, and you’ll be rewarded with a successful harvest.

About the Author

Big Hippo Cannabis Seeds

Big Hippo supply top of the range cannabis seeds in the UK, including grow equipment, and CBD products - we also provide cannabis-related articles and information on our website at Big Hippo.

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