How to Grow Cannabis From Seed: Step-by-Step Guide

Quick answer

Germinate cannabis seeds in a moist paper towel or a small pot of light soil at 70°F to 80°F. Move sprouts under a grow light or sun with 18 hours of light and 6 hours of dark. Keep soil pH near 6.0 to 7.0, water when the top inch dries, and switch to a 12/12 light schedule when you want flowering.

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Prerequisites

• Confirm that cannabis cultivation is legal in your state and local area.
• Buy seeds from a reputable source.
• Gather light soil, small pots, a grow light, a timer, a pH pen, and a thermometer.
• Set up a ventilated space with steady temperatures and low humidity during seedling stage.

Step-by-step

1. Check state and local cannabis cultivation rules before you plant.
2. Pick seeds that match your space, light setup, and preferred effects.
3. Clean pots, trays, and tools with soap and water.
4. Moisten a paper towel and place seeds between the folds, then keep it warm and dark.
5. Plant each seed with its taproot down in light soil at about 0.5 inch deep.
6. Place seedlings under 18/6 light at 24 inches from the canopy.
7. Water when the top inch of soil feels dry.
8. Feed a mild vegetative nutrient mix after the first set of true leaves.
9. Top or train plants once they have four to five nodes.
10. Switch the timer to 12/12 when plants fill half the grow space.
11. Harvest when trichomes turn cloudy, usually 8 to 10 weeks into flowering.

Germination method

The paper towel method gives you a clear view of the taproot. Keep the towel damp, not soaked. Check daily. Most viable seeds split within 24 to 72 hours. Plant the seed as soon as the taproot reaches about 0.25 inch. Handle the root with clean tweezers and avoid touching it.

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Seedling care

Seedlings need mild light and steady moisture. Keep the light at 24 inches and raise it if leaves cup or bleach. Water in a small ring around the stem to push roots outward. Do not soak the whole pot. A dome helps keep humidity high for the first few days, then remove it to improve airflow.

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Vegetative stage

Plants grow fast under 18/6 light. Water deeply when the pot feels light. Feed every other watering with a balanced vegetative nutrient mix. Keep daytime temperatures near 75°F and nighttime temperatures above 65°F. Inspect leaf undersides for mites and aphids each week.

Flowering

Cannabis is a short-day plant, so long dark periods trigger flowering. Set the timer to 12 hours of light and 12 hours of dark. Keep the dark period free of light leaks. Flowers form in clusters at branch tips. Stop high-nitrogen feeds and switch to a bloom formula.

Common problems

• Stretched seedlings: move the light closer.
• Yellow lower leaves: check pH and nitrogen levels.
• Drooping leaves: water less and improve drainage.
• Slow germination: raise the temperature and check seed age.