How to Grow a Marijuana Plant Indoors From a Seed

If you’re a complete beginner, our guide on how to grow a marijuana plant indoors from a seed can get you up to speed. Growing marijuana from seeds has never been easier. If you live in a state that allows cannabis home cultivation, you can grow a certain number of plants inside of your home. Make the most of your spare closet, garage, or attic with our handy growing guide.

Follow the Rules for Growing a Marijuana Plant Indoors

Before you rush to your nearest gardening & hydroponics store, double-check your state and local cannabis laws. States that allow home cannabis cultivation have varying limits on how many mature and young plants you can own. In addition, each jurisdiction has specific rules on many aspects of your garden including:

  • The size of a garden
  • The location of a garden
  • The energy use
  • The use of flammable materials

Once you determine the limitations and restrictions in your area, you can proceed to set up your indoor garden.

What’s the Timeline for Growing a Marijuana Plant?

Cannabis growing times vary, but generally, plants can grow in a few short months.

The average cannabis plant takes between 3-4 months to mature. Some autoflowering strains can fully mature in 2-3 months.

That’s not counting the time it takes to dry and cure the marijuana buds. Drying can take as little as a week and curing a few weeks or months. Drying and curing times vary depending on your preference.

Here’s a quick breakdown of every step of the growing process:

  1. Gathering the equipment: 1 day-2 weeks
  2. Sourcing the seeds: 1 day-4 weeks
  3. Germination: 12 hours-8 days
  4. Seedling Phase: 1 week-4 weeks
  5. Vegetative Phase: 2 weeks-6 months
  6. Flowering Phase: 6 weeks-3 months
  7. Harvesting: 1-3 days
  8. Drying: 1-2 weeks
  9. Curing: 2-3 months

For more information about every step of the growing timeline, check out our blog post “How Long Does It Take To Grow Weed?”

Here’s What You’ll Need

High-Quality Seeds

If you’re growing a marijuana plant from a seed, you better have seeds with high-quality genetics. High-quality seeds are available at your nearest dispensary or from an online seed bank. Dispensaries usually have a more limited selection compared to the hundreds of varieties available online. However, dispensaries may offer a personalized service.

If you’re lucky and have a friend who grows marijuana, they can provide you with cannabis seeds from their plants. Ideally, you want to start with a seed that has a hard shell and a smooth and undamaged surface. Steer clear of seeds with a green or white color and soft shell.

Generally, cannabis seeds are categorized as the following:

  • Feminized: Seeds bred to produce only female plants
  • Regular: Seeds that have a 50/50 chance of being male or female
  • Autoflowering: Seeds that automatically switch from the vegetative to the flowering stage based on age

Pro tip: As a beginner, the easiest seeds to grow are feminized. If you’re looking to grow cannabis buds, regular seeds increase the risk of producing a non-flowering male plant.

Location

Climate-controlled indoor environments can produce some of the best buds around. An indoor grow room gives you the ability to recreate a natural environment in a way that brings out the best traits of your seed.

Literally any free space such as a room, closet, or garage gives you enough space to grow at least one plant. For beginners, an indoor grow tent, also known as a grow box, is a convenient and effective location for your garden.

Grow tents vary in size, price, and quality. Ideally, you want a marijuana grow tent that is light proof and has reflective walls to create an ultra-bright environment. A grow tent is your all-in-one solution to contain your plants, hang up lights, and set up a ventilation system.

Check out our lists of the Best Cannabis Grow Tents and Grow Kits (includes lights, medium, container, etc.)

Growing marijuana plant indoors from a seed under lightGrowing marijuana plant indoors from a seed under light

Marijuana seeds under light growing from a seed

Lighting

Artificial light systems are used to replicate natural sunlight. There are a few types of grow lights available that work for indoor cannabis gardens.

  • LED: An easy-to-use and energy-saving light source with a long shelf life.
  • HID: A professional-grade and high-intensity light.
  • Fluorescent: A readily available light for small spaces.

For beginners, a fluorescent lighting system can light up small gardens at the expense of efficiency and yields. LEDs are another excellent option, although they are more expensive than fluorescent lights.

HID lights such as light-emitting ceramic (LEC) grow lights feature ceramic heating elements. The best LECs give off the high intensity of HIDs and low heat of LEDs.

Ideally, you want to get a lighting system with a full spectrum of light capable of meeting the different needs of the vegetative and flowering stages.

Check out our list of the best HID, fluorescent, and LED grow lights.

Medium

All cannabis plants grow inside of a medium. Soil is the most common medium but there are also soilless and hydroponic mediums that work just as well and, sometimes, better. Beginners can start with a soil-based or soil-less method.

  • Soil: High-quality potting soil from reputable brands
  • Soilless: An inert medium such as her light, coco coir, vermiculite, and more.

If it’s your first time growing, buying pre-made soil or soilless mixes can get you started. Some pre-made soils may use organic nutrients and other growth-promoting agents.

Container

A container is used to hold the growing medium and allow for drainage. Aim for a container with more than enough space to allow the roots to grow and avoid restriction. A standard nursery container with drainage holes can work.

A fabric pot, also known as a smart pot, is perfect for first-time growers. Smart pots prevent over-watering and allow for optimal root growth. Air pots are similar in nature but are made of plastic and have openings on the sides for drainage and air circulation.

Most cannabis plants can grow in a 2-3 gallon pot. You can also start your seedling in a 1 gallon smart pot and transplant it as it grows.

Nutrients for Growing a Marijuana Plant Indoors from a Seed

Marijuana plants need a wide range of macro and micronutrients. Marijuana plants primarily used the following mineral nutrients:

  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)
  • Calcium
  • Magnesium
  • Sulfur

Experienced users can make their own super soil full of natural and organic nutrients. As a novice grower, you’ll likely have to supplement your garden with nutrient mixes meant for soil or hydroponic gardens.

Nutrient solutions typically feature 3 numbers on the front of the label, which represent the N-P-K ratio. The NPK numbers represent the nutrients percentage by weight. Nutrients meant for hydroponic marijuana gardens are sold as concentrated mineral salts that must be diluted in water before they are fed to the plants.

Nutrient solutions are also categorized in grow and bloom solutions. Grow solutions have a higher nitrogen percentage for vegetative growth. Bloom solutions have a higher phosphorus percentage for the flowering phase.

Pro tip: Start off with 25% of the recommended nutrient levels and work your way up to the recommended strength. Increase or decrease the strength depending on the vitality of your plants.

The Marijuana Plant’s Life Cycle From a Seed

Germination

Seeds require warm and wet environments to start sprouting. One of the easiest and most affordable ways to start sprouting your marijuana seeds is using the paper towel method.

  1. Gather two plates, seeds and paper towels
  2. Soak 4 sheets of paper in distilled water
  3. Allow the excess water to run off
  4. Place 2 sheets of the paper towel on 1 of the plates
  5. Place the seeds at least 1 inch away from each other
  6. Cover the seeds with the other 2 sheets of paper towel
  7. Cover the seeds with the second plate to create a dark and secure space
  8. Keep the area between 70 to 90º F
  9. Wait several days for the seeds to split and sprout
  10. Transfer the sprout into a small pot

Vegetative Stage of a Marijuana Plant

During the vegetative stage, a plant begins to grow its foliage, which may require topping or training. Indoor Growers must provide their plants with at least 18 hours of light and 6 hours of darkness a day. A timer can help you automate your lighting.

During the vegetative stage, you’ll need to provide water whenever the top of the soil feels dry to the touch. In terms of its nutrient intake, follow the packages feeding schedule at a lower than recommended dose and build up if needed.

Maintain an optimal room temperature between 70 and 85º F. Try to maintain a low humidity environment to avoid mold. Provide your plants with enough air circulation to keep your garden at an optimal temperature.

As you gain more experience, you’ll learn to detect problems in your garden and how to troubleshoot. For a quick primer, check out our guide on common plant health problems.

Flowering Stage

During the flowering stage, your female marijuana plants will begin or will have already started to develop its flower buds. If grown from a regular seed, you may see sex traits found in male plants. Remove these plants from your garden.

During the flowering stage, your plant will need a 12-12 light and darkness lighting schedule. Flowering times vary by strain but generally they last between 8-9 weeks. Make sure to regularly prune your plants to give every bud site the light it needs.

Flushing

During the final stages of the flowering, some cannabis growers may choose to flush their plants of most of their nutrients. For a week or two, growers chose to feed plants only water. Flushing can cause signs of nutrient deficiency such as yellow leaves, but this just ensures all the nutrients are gone.

Harvest Time of Cannabis Plants

Harvesting times vary and it can be tricky to choose the best time.

One of the easiest ways to know when to harvest is by looking at the little hairs, also known as pistils, growing on your bud. These pistils start off white and then curl and darken over time into a yellow, red, or other bright color. One of the best times to harvest is when about one-half to one-third of the pistils have changed color.

For a more accurate representation of when to harvest, look at the cannabis trichomes on the buds. If possible, use a magnifying glass to get a closer look at these resinous glands. Trichomes start off clear and darken over time. The best time to harvest is when about one-half to one-third of trichomes have darkened.

Cut the branches from the base using sharp shears or scissors and remove the big fan leaves. Place your branches in plastic trays. You can divide your branches into smaller units depending on your preference.

Drying

Trying is the slow process of allowing the moisture to naturally evaporate from your buds. Place your bud branches in an area with temperatures between 60 and 70º F and a relative humidity (RH) of about 50%.

When harvesting, cut your branches between 12 to 16 inches long. You can hang them from a strong string or wire.

When drying, use dehumidifiers heaters to regulate the temperature. You’ll know when your plants are dry enough when the branches break off with a sharp snap.

Curing

Curing is a slow drying process that happens in an airtight and UV-protected glass jar. Cannabis buds can be cured for a week or a couple of months. During the process, you want to keep your jar in a dark and cool space. Every day, open the lid and allow it moisture to evaporate for about 10 minutes. Curing times vary depending on strain and your preference.

Now that you know how to grow a marijuana plant from a seed indoors, you can experiment with different strains and make a variety of infused products including edibles, topicals, and extracts.

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