How to Grow Weed from Seeds to Harvest Indoor | All the Facts and Tips You Need

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by Morgan

Last update:

August 29, 2023

How To Choose The Right Lighting For Your Marijuana Grow Room

Growing weed indoors has never been more popular than it is today. Not only does growing marijuana indoors save you money, but it gives the grower greater control over the conditions that make for the best marijuana. Growing weed from seeds to harvest makes for an easier transition from harvesting your first plant to larger-scale growing.

The process can be daunting to any new marijuana grower, especially those who have never grown regular plants before. Most people know what to do with seed once it has sprouted and how to grow from plant to harvest. However, there are some differences in how this applies to growing cannabis indoors. Continue reading to learn more about how you can increase your cannabis plants indoors, from cannabis seeds to harvest;

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Find and Prepare a Growing Space

The space you choose for growing cannabis will depend on the size of your plants. You will need at least 3 feet by 3 feet of room to grow a single plant and larger spaces if you plan to produce more than one. Identify a spot in your home where the temperature is stable and between 18 and 24 degrees Celsius. Ensure enough light in the chosen space- at least 600 lux is ideal. If you do not have a naturally bright room, you will need to provide artificial grow light.

Get Suitable Pots and Soil

To grow cannabis, you will need to use soil designed for plants that grow in soil. You can either make your growing medium mix or buy a pre-made mix. A good soil mix will have components like coco coir, perlite, vermiculite, and compost. Make sure to get big enough pots for your plants to grow in. The roots need plenty of space to grow.

Install a Grow Light

If you are not growing in a naturally bright space, you will need to install a grow light. A grow light should be placed around 18 inches above the plants and cover the growing area. In the United States, United Kingdom, and Canada, the demand for cannabis indoor cannabis cultivation is increasing, and for better cultivation of plants growers are using LED grow lights.

Include Ventilations

To ensure your plants grow healthy, you will need to provide them with some airflow. Make sure the space you are growing in has some ventilation, whether that is through windows, a fan, or both.

Get the Right Seeds

When growing cannabis indoors, it is best to start with right marijuana seeds. You can buy feminized cannabis seeds from various places online and in physical stores. Ensure to get seeds bred for growing indoors- these will have a higher yield and will be easier to grow than cannabis strains bred for outdoor growing. Also, ensure to get the excellent, quality seeds with the following features:

  • Auto-flowering seeds - these will grow into plants that flower automatically, regardless of the light cycle
  • Feminized seeds - these seeds will only produce female plants, which is what you want when you grow cannabis for smoking
  • High THC content - the higher the THC content of a seed strain, the more potent the resulting buds.
weed seed

The Planting Process

Germinating the Seeds

Once you have chosen a growing space and obtained the necessary pots, soil, light, and seeds, it is time to germinate them. Seeds will grow best when they are wet and in a warm place. You can start soaking the seeds in water for a few hours before planting them or placing them in-between a damp paper towel and then put that towel in a warm place. The germinated seeds will start sprouting within a few days.

Other methods of the germination process you should consider are:

  • Planting them in soil and then watering them
  • Using a rooting hormone to help with the germination process
  • Putting them in a cup of water and changing the water every day until they sprout

Planting the Seeds

Once the cannabis seeds start germinating, it is time to plant them in the soil. First, prepare the soil mix by adding water until it is damp but not wet. Then place the seeds in the ground, making sure to plant marijuana seeds about 2 inches below the surface. Gently water the seeds and make sure the soil remains moist- but not wet- until the plants have started to grow.

planting the seed in soil

The Seedlings

Once the seeds have germinated and transferred to the soil, you will need to wait a few weeks for the seeds to grow into seedlings. During this time, make sure to keep the soil moist and give the plants plenty of light. You can start fertilizing the plants once they have developed their first true leaves. At this stage, they only require fertilizer every other week.

The Vegetative Stage

Once your weed seedlings start to grow, you will need to move them to prepare for the vegetative stage. What prompts this action is that they will begin to grow larger and taller. For the plants to vegetate effectively, they will need to be in a space with at least 18 hours of light each day. You can keep the plants in this space for as long as possible but gradually increase the hours of light they are exposed to as you move closer to the harvest.

Thinning and Weeding

When your weed seedlings reach a height of about 6 inches, you will need to thin them out. Remove the smaller plants so that only the larger ones remain. You will also need to weed out any plants that are not cannabis, as these will steal the nutrients and space from your cannabis plants.

weed growing stages

The Flowering Stage

Once the plants have reached a height you are happy with, it is time to move them into the flowering space. To start flowering, the female plant will need to be exposed to 12 hours in the light and at least 12 hours in the darkness daily. You can keep the plants in this stage for as long as possible but gradually reduce the hours of light they are exposed to as you move closer to the harvest.


Once the plants are about 12 inches, it is time to pollinate them. For indoor plants, the best option is manual pollination. Use a small brush to transfer the weed pollen from the male plants to the female plants. You can also pollinate by hand, but this is a more complex process. However, to effectively do this, learn the sexes of plants of your plants as explained below:

How Do You Identify Male and Female Weed Plants?

The easiest way to identify male and female plants is by looking at the pistils on the buds. Female plants will have long, wispy pistils, while male plants will have short, stubby pistils. You can also do a genetic test to determine the sex of the cannabis plant.

If you are growing weeds from seeds, you must make sure that you only produce female plants. It is possible by checking the pistils on the buds or by doing a genetic test to determine the gender of your plants for an effective fertilization process.

the plant and the brush

Do We Have Hermaphrodite Weed Plants?

The answer to this question is yes. That means that the plant has male and female reproductive organs and can self-pollinate. As a result, the buds from these plants will not be as potent as those from plants pollinated by another cannabis plant. Notably, the aforementioned advice to use only female plants is best in this case. 

The Harvest

When the buds on the plants have started to turn from white to light green, it is time to harvest them. Cut the buds off the plant and then hang them upside down in a cool, dark place to dry. Once they are completely dry, you should store them in an airtight container.

Primary methods for determining when to harvest;

  • The color of the buds- They should be light green when ready to harvest
  • The size of the buds- They should be big and fat when ready to harvest
  • The smell of the buds- They should smell skunky when ready to harvest
  • The trichomes on the buds- They should be cloudy with amber heads when ready to harvest
  • The pistils on the buds- When the weed pistils turn from white to brown, the buds are ready to harvest

Storage and Seed Extraction

After the buds have been harvested, you will need to store them in an airtight container until you are ready to use them. You can also extract the seeds from the buds and keep them for later use. Place the buds in a bag and then smash them with a hammer until broken up. Next, pour the broken-up buds into a bowl and then use a spoon to separate the seeds from the plant matter.

cut buds

Basic Care For the Seeds and Weed Plants

Your cannabis seeds will need to get watered regularly. Keep an eye on the soil and make sure it is not drying out. You should fertilize the soil occasionally. If you are using artificial light, keep the light shining on the plants for at least 18 hours per day. You will also need to weed out any plants that are not cannabis, as these will steal the nutrients and space from your plants.

Some other tips for taking care of your cannabis seeds include;

  • Make sure the soil is damp but not wet
  • Keep the plants in a space with plenty of light
  • Fertilize the plants every other week
  • Water the plants regularly
  • Weed out any non-cannabis plants

Best Cannabis Strains for Indoor Planting

When you grow cannabis indoors, a few different cannabis strains tend to do better than others. Listed are some of the best strains for indoor planting;

  • Northern Lights; This strain is known for its short stature and high yields. It is also a very resilient strain, meaning it is easy to grow and does not require much care.
  • White Widow; This strain is known to have high THC levels and potent effects. It's a suitable choice for those looking for a potent cannabis strain that will produce a lot of buds.
  • Blue Dream; This strain is a hybrid of blueberry and haze, two prevalent strains. It is known for its high THC and CBD levels and its sweet blueberry flavor.
  • Harlequin; This strain is a Sativa-dominant hybrid known for its high CBD levels. It makes it a good choice for those looking for relief from pain, anxiety, and other conditions.
  • Skunk No.1; This strain is a hybrid of Afghani and Cannabis Sativa. It is known for its potent, skunky smell and high THC levels.
  • Sour Diesel; This strain is a Sativa-dominant hybrid known for its powerful energy and euphoric effects. It's a good strain for anyone looking for weed to help them get through the day.
  • OG Kush; This strain is a hybrid of Chemdawg and the Hindu Kush. It is known for its intense cerebral effects and earthy, piney flavor.
  • Granddaddy Purple; This strain is an Indica-dominant hybrid known for its relaxing and euphoric effects.

As you can see, several different cannabis strains do well when grown indoors. Choose a strain that best suits your preference and start your indoor cannabis garden.


How Many Hours of Light Do Cannabis Seeds Need?

The cannabis seeds need at least 18 hours of light per day to grow properly. If you are using artificial light, keep the light shining on the plants for at least 18 hours per day.

What’s the Best Soil for Growing Weeds Indoors?

There is no one-size-fits-all answer to this question, as the best soil for growing weeds indoors will vary depending on your location's climate and other environmental factors. However, an excellent general rule is to use soil rich in organic materials and has a pH averaging between 6.5 and 7.0.

Can I Grow Weed Under LED Lights?

Yes, you can grow your marijuana plant under LED lights. However, it is essential to note that LED lights are not as efficient as other types of lighting and may result in lower yields.

How Long Does It Take Weed to Fully Mature?

Indoor cannabis plants typically take between 8-and 10 weeks to mature. However, the time for a plant to fully mature will vary depending on the strain and growing conditions.

Can I Harvest My Plants Early?

Yes, you can harvest your weed plant early. However, premature harvesting can result in lower yields and reduced potency. It is recommended to wait until the buds are fully mature before harvesting.

How Do I Know When the Cannabis Plants Are Ready to Harvest?

The best way to determine when your marijuana plants are ready to harvest is to look for the signs of maturity. The buds will swell, and the pistils will turn from white to brown or red. You can also test the potency of the buds by using a THC testing kit.

Final Thoughts

Growing your cannabis at home is an immensely satisfying process. You will take pride in what you have accomplished, knowing that you did it yourself. Starting with seeds from a reputable source ensures the process is straightforward. If you require more information about growing weed from seed, explore the 420GreenThumb for more insights. Happy growing!

🌿  Join my "growing" community 
of 5000+ happy
cannabis farmers! πŸ‘©β€πŸŒΎ

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from seeds to smoke! 
β€” Morgan, 420GreenThumb 🌱

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About the author 


I discovered the benefits of Cannabis at a young age in 2002, with years of trial and error, my knowledge grew just like my plants. As my love for cannabis unfolded I began to teach and learn, trying to gain as much information and practical growing experience.

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