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starting cannabis seeds indoors

Fill the cups with the soil mix and tap each cup a couple of times on the table to eliminate air pockets. Add more soil if needed, tap it down again to leave a half-inch space between the top of the soil and the rim of the cup. Repeat until all the cups are filled. Set up your grow table and lights. Ready? The table is all set. The lights are on. The cups are shoulder to shoulder in rows, waiting to fulfill their roles.

How to Grow Your Own Cannabis Plants From Seeds

Takeaway: Back in the last millennium, before cloning swept the country like the hula hoop, people actually grew cannabis plants from seed. Primitive, huh? But where there’s a will, they’ll surely find a way. While that’s all changed now (hello, cloning!) you can only clone so many times before you have to buy more plants or get back to basics with seeds.

Growing from seed is all about the quality of your seeds. Plants will never be better than the seeds they grew from. Back in the day, there weren’t any seed shops, so seeds were saved from exceptional buds, but it was all a crapshoot with a lot of trial and error. Luckily, now we know better.

Starting from seed isn’t difficult and you don’t need to be an experienced gardener, but the process is a journey in stages, not a direct flight. Cannabis plants are perfect for growing from seed because they have a short life cycle. That being said, be prepared to check your plants every day for moisture, insects, diseases, nutrient deficiencies and light. If you can’t make the time and work commitment, perhaps you should forget the idea. Here’s my list of what I used for my first grow. Nothing high-tech—my grow room was a walk-in closet with louvered doors and a clothes bar to hang my lights.

  • A four-foot table or two sawhorses with plywood on top
  • A piece of thick plastic or a waterproof tablecloth for spill protection
  • Potting soil for seedlings
  • Clean sand
  • Seeds (of desired strain if purchasing)
  • Five-gallon pail for mixing soil
  • A four-foot shop light with chains and S hooks
  • One full-spectrum red fluorescent grow light
  • One regular white fluorescent tube bulb
  • Light timer
  • Five-ounce opaque drink cups
  • Eight-ounce drink cups
  • pH kit
  • Plant flats or trays
  • Plastic kitchen wrap

Best Lighting for Cannabis Seedlings

If you’re on a budget, fluorescents offer the biggest bang for your buck when getting light to you cannabis seedlings. Don’t forget to factor in the cost of electricity and bulb replacement. To make sure all my plants got an equal amount of light, I turned the trays 180 degrees every day. I especially liked the ease of raising the shop light one link at a time as the plants grew. You can maximize your light by using a room with white walls or surrounding your grow table with movable reflecting foil-covered cardboard or hanging sheets of Mylar—mirrors don’t work well for reflecting light.

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Germinating Cannabis

Mature cannabis seeds are dark brown, sometimes with swirly patterns or stripes. Discard immature pale or greenish-colored seeds. I’ve never started seeds in soil, preferring the Japanese method of “proving” seeds first; there’s no sense planting dud seeds. I germinated my seeds in a moistened, loosely rolled up paper towel on a plate in indirect light on the kitchen counter where I could keep an eye on progress. Keep the paper towel moist, but not lying in a puddle of water or the seeds will rot.

Some seeds germinate in a couple of days, while some take up to a week, depending on their temperature. It’s helpful to know that the seeds will produce male and female plants. Back in the Dark Ages, I always started 16 cups of seeds in hope of ending up with four females. That’s no longer a problem if you can buy feminized seeds, which are guaranteed to be females. I planted two sprouted seeds about one inch apart per cup because frequently one seedling will be bigger and stronger than the other. Go with the bigger one and pinch off the smaller one at the soil level.

The beauty of starting seedlings in the opaque cups is that you can see the root growth. Poke some drainage holes around the cup bases. It’s quicker to do the drain holes with the cups in a stack. As you finish each cup, slip it in the other end of the stack or you’ll waste crumpled up cups. Mix the potting soil with enough sand to give the fluffy soil more body. Add water gradually, mixing well to moisten.

Fill the cups with the soil mix and tap each cup a couple of times on the table to eliminate air pockets. Add more soil if needed, tap it down again to leave a half-inch space between the top of the soil and the rim of the cup. Repeat until all the cups are filled. Set up your grow table and lights. Ready? The table is all set. The lights are on. The cups are shoulder to shoulder in rows, waiting to fulfill their roles.

Transplanting Cannabis Seedlings

My tools of choice for planting were a small wooden matchstick and a wooden toothpick. I made two small holes with the clean end of the match about one quarter inch deep and a half inch apart and not too close to the side of the cup. I picked out two sprouted seeds at a time from the paper towel, careful not to touch the sprout, and dropped them into the match holes and used the tip of a toothpick to scuff soil into the holes, then lightly tamped the spots with one finger. Keep the remaining sprouted seeds covered so they don’t dry out. Repeat until all the cups are planted.

Put as many cups that fit into shallow flats or trays and then drape a long piece of kitchen plastic wrap over everything, tucking the ends under the trays to create a mini greenhouse. When this step is finished, the plants get to sunbathe under the lights for the next six weeks or so of the seedling phase.

In a few days, two primary leaves will appear and you can do your happy dance. Soon the next pair of leaves will appear and the first ones will drop off. If condensation forms under the plastic wrap, uncover the seedlings to release the excess moisture and then replace with fresh wrap. During the seedling phase, keep the soil moist but not wet and only water from the bottom from so the roots stretch down long and strong.

Water with a spray bottle until the first leaves appear, and then water from the bottom; the soil around the stem needs to stay dry to avoid stem rot. Fill pitchers or buckets with tap water and let sit uncovered until room temperature and the chlorine has evaporated into the air. Hard water is fine, but don’t use artificially softened water because it contains too much salt and other harmful additives.

I’m an organic gardener. While I don’t object to a little bloom booster to convince some reluctant annuals to step it up, I want everything that goes in my body to be as natural as possible. Plants need nitrogen to grow. When I had access to a mountain of free rotted horse manure, I fertilized with manure tea.

Throw a shovelful of manure in a bucket, fill with water, let it sit a couple of days and water with the tea. It worked fine for me. There are “hot” manures and “cold” manures. Hot manures have the highest nitrogen, but have to be aged. Cold cow manure has lower nitrogen but can be used hot out of the barn. Rabbit manure is cold, but some growers call it nitrogen on steroids. If slogging around in barnyards doesn’t appeal to you, you could use fish or seaweed emulsions or any of the other excellent natural fertilizers available at your local hydroponics supplier.

Check your soil pH regularly. Plants grown in soil like a pH about 7. If your soil drops below 6, add a light sprinkling of ground limestone before watering. If the soil is above 8—too alkaline—sprinkle around a concoction of cottonseed meal, lemon peels and ground coffee.

For repotting, discontinue the plastic wrap when the third set of leaves appear. When you see that the roots have reached the bottom of the cups, it’s time to repot the little darlings into the eight-ounce cups. In my experience, the plants do better stepping up to the bigger cup instead of going directly into three-quart pots. Repotting can be tricky, so take your time here. The plants shock easily with too much jostling or rough handling. Get the larger cups ready, poke the drain holes and fill with enough soil mix so the seedlings will be at the same depth as in the first cups. Before removing from the smaller cups, lightly water them so everything stays together.

Tip the cup upside down in your open hand with the seedling stem between your fingers. Gently squeeze the sides of the cup with your other hand and the seedling will drop out in one piece. Don’t pull it out by the stem! Place the seedling in its new home, filling around it with more soil, and make sure it isn’t deeper or shallower than in the smaller cup. This is important. Compress the soil lightly for any air pockets.

Entering the Vegetative Stage

During the vegetative phase, leave the lights on 24/7 and as close to the leaves as possible without touching. If the lights are too high, the stems will grow weak and spindly. You want the plants to remain compact. When your plants really take off, they may grow an inch a day. Keep a sharp eye on the distance between the tops of the plants and the lights. Fluorescents are cool and won’t burn the leaves, but keep adjusting your lights upwards to stay ahead of the growth.

Rotate your plants so they all get enough light. When plants are starting to bud, rough handling or a sudden change in temperature or light will drive them into shock. When you see your plants are beginning to outgrow the cups, it’s time to pot up again, this time to three-quart containers commonly found at nurseries. Always wash used pots in hot soapy water before reusing.


Toward the end of the vegetative and budding phase, you’ll be able to sex your plants. Males have two pollen-filled sacs that are easy to see and females have a pair of white V-shaped hairs. One male plant is enough to pollinate all your females so they produce seeds. I didn’t grow for seeds, so I quickly yanked all the male plants. Male plants are low in THC, are harsh-tasting and give many people a massive headache. Unpollinated females produce more flowers, buds and THC.

For even more plants, remove the unproductive lower stems and leaves on your plants, and then make two or three shallow downward slices on the main stem with a clean blade and insert a graft slip dipped in root stimulant in each cut. Put a small piece of tape around the cuts. The grafts can be other varieties, not just the same as the host plant. Soon you’ll have new growth from all your grafts, giving you maximum yields.

Starting cannabis seeds indoors
In this case, you need to make sure that the outside daylight hours are long enough to allow for the vegetative phase of your plants.

How To Start Your Cannabis Plants Indoors And Move Them Outdoors

There can be situations where it makes sense that you start plants indoors but want to move them outdoors, such as for flowering or that they can continue growing outside to their full potential. Moving plants outdoors is doable, but you need to know about the caveats. Learn important facts for starting your plants indoors and moving them outdoors!

You can definitely start marijuana plants indoors and move them outdoors at a later time. Doing so can make sense when you want to start your plants in a safe and controlled environment first and then, for example for flowering, would like them outside so they can enjoy the power of the sun for optimal yield. Moving plants outdoors can also be an option if you were to run out of growing space but want to grow your plants to their full potential outdoors.

However, moving cannabis plants outdoors, such as when the plants are in the growing (vegetative) phase and you want to flower them or in case you want them to keep growing outside comes with caveats that you need to know about. Let us talk about what you need to know about safely moving your plants outside.


Unless you are growing autoflowering strains which don’t care about daylight hours and light schedules, the big caveat with moving your marijuana plants outdoors has to do with the natural daylight hours. Unlike indoors where you have control over your lighting duration, you don’t have this control outdoors. Since non-autoflowering strains are depending on light cycles to determine whether to grow or whether to flower, the natural outdoor daylight must be taken into consideration.

There are possible scenarios where you would want to move your plants outside and each scenario would need that you know about how the natural light outdoors could possibly influence your grow.


Let’s for the sake of easiness assume a typical indoor growing environment where you grow under artificial light on a 18/6 light schedule, such as in a grow tent or green house with your light on a timer.

For vegging, your plants can in theory stay under the 18/6 light schedule indefinitely. As long as the light cycle doesn’t change, your plants will grow and nothing shall really keep them from happily doing so.

In this case, a typical scenario where you might want to move your vegging plants outdoors for flowering could be once the plants reached a certain height, say when they reached 50 cm or so.

The caveat here is that you want to put the plants outside so they start to flower and would do so uninterrupted until harvest time which would typically take around 7-8 weeks. For your plants to flower, you want the daylight hours short enough so the plants won’t go into what’s called “re-vegging” which would negatively influence your plant’s growth and yield.

Now, from June 21st on, the daylight duration outdoors will steadily decrease until the Winter solstice on December 21st. Available daylight hours will again slowly increase after December with the maximum of daylight hours again available around June 21st.

You have several options for flowering cannabis outdoors after you grew them indoors:

  • You move our plants outdoors in late summer or early fall where the daylight hours are already short enough to initiate flowering right away.
  • You move your plants outdoors early in spring. Even if at this time daylight is already gradually increasing again, it will still be short enough for your plants to flower without the risk of re-vegging. (The right timing here is important! Put them out too late in spring and your plants would re-veg before harvest!)

When you put your plants outdoors for flowering, for example in spring, you want to avoid that your plants flower first but then stop doing so and go into a re-vegetative phase. (Because the daylight duration may become too long as spring progresses). When your plants go into re-vegging, it would negatively affect your yield!

For this reason you want to put our plants for flowering outdoors early enough in the year so they can finish flowering and are ready to harvest about mid-May. This would be the critical date otherwise they re-veg which you want to avoid.You wait until the end of June to move your plants outdoors. At the end of June, your plants will still spend some weeks growing but then begin to flower as summer comes to an end and autumn with its shorter days comes along.


  • If you want to continue to “veg” your plants outdoors, there are similar caveats as described above except that now you want to move your plants outdoors so they continue growing without premature flowering.

In this case, you need to make sure that the outside daylight hours are long enough to allow for the vegetative phase of your plants.

  • Many growers who move vegging plants outside wait until the end of June to do so. At the end of June, shortly after the spring equinox, available daylight hours outdoors are the year’s longest which means there is no risk for premature flowering when you move plants from a 18/6 light schedule.

Know that should you move your vegging plants outside at another date, say in early spring or later in fall, they would start to flower, rather than continue growing.

  • Yet another option for putting your plants outside can be if you adjust your indoor lighting schedule to prepare them for the move to the outdoors. This means you would start growing indoors but follow the natural outdoor photoperiod. Let’s say there are currently 14 hours of natural light per day, then you would adjust your indoor light schedule accordingly and also set it to 14 hours. You would gradually adjust your indoor light duration every few days for a few minutes to keep the two light cycles (indoors and outdoors) in sync. This would then allow you to put your plants outside without the negative effects of a sudden difference in light duration.

There can be many reasons why you would want to start cannabis plants indoors and move them outdoors at a later time. You could for example start seedlings indoors so that they are sound and safe and protected from the cold in fall and winter. In the spring, your plants may be ready and eager to go outside so they can soak-in the sun and grow to their max potential. If you know about the natural light cycles and how they can influence the growth of your plants, you can move them outdoors without any negative surprises!