Grow Weed Starting From Seed
“Don’t judge each day by the harvest you reap but by the seeds that you plant.”
Growing your own cannabis plant starting from seed is a remarkable journey. Understanding the biology of the plant is one thing, but comprehending how a little miracle bean can turn into a gigantic tree producing flowers that can affect your body and mind is nothing short of an evolutionary miracle. Or rather a co-evolutionary story of plant and human.
Start Growing Weed From Seed
Our favorite thing about growing your own weed starting from a seed , rather than a clone, is that you get to see the full life cycle and enjoy a plant that is unique, just like you. An entirely new genetic makeup will enter the world for the first time, and if you’re lucky, something remarkable might be born.
Raising a cannabis seedling , however, requires some patience, gentle hands, and a smidgen of luck. Thankfully pot seeds are remarkably vigorous because they are what’s called endosperm seeds , which means they have almost pre-formed cotyledon leaves before you even add water. Below is a brief guide on the techniques we have found yield the most success when starting seeds and raising your seedling to a healthy plant ready for transplanting. And, don’t forget, a Pot for Pot’s Complete Grow Kits take the guesswork out so you always wind up with a splendid harvest!
1) Germinating Your Cannabis Seed
To accelerate germination, soak your seed in a small container with lukewarm water and place it in a dark and warm place (like a kitchen cabinet) for 12-24 hours, but no longer. By drenching the seed, it absorbs the water thoroughly, activating the germination process on a physical and chemical level. Doing this helps to loosen the shell as it becomes a little softer making it easier for the embryo to crack it open. When your seed sinks to the bottom, it is ready to be planted, and sometimes the seed will pop out a small taproot. A seed can still be planted though if it does not sink or put out a taproot. When a seed pops a taproot (often called a tail), it becomes more vulnerable and it is better to plant it before this root emerges.
2) Planting Your Weed Seed
We see best results with seedling pellets that are made of a mix of compressed peat moss and coco husk. To expand, soak it in water for 10 to 15 minutes. Using warmer, lukewarm water, instead of cold water, will speed up the time the pellet takes to fully expand. Once your seedling pellet has absorbed enough water and has expanded to its maximum size, gently squeeze to remove excess water. The growing medium should be like a damp sponge that would not leave streaks on the table. Dig a small hole about 1/4 inch deep for your seed. Use a spoon to lift the seed out of its bath. If it has popped out a taproot be careful not to damage it. Gently place the seed into the hole and lightly cover it with dirt from the pellet. Now that you have started the germination process, your seedling will come above ground within two weeks. The older the seed, the longer it takes for it to germinate.
Want an easy-to-use starter kit for Cannabis seedlings? Check out our Seedling Starter Kit, perfect for nurturing your germinated seeds into viable, healthy plants.
3) Weed Seedling Sprouts
Perhaps the most exciting stage, your plant baby will come above ground in 1-2 weeks, with the average popping up in 5 to 7 days after planting. As your seedling comes above the soil, its shell might take a few days to fall off. It’s best to leave it alone, nature has the job covered. If it does not come above ground after about two weeks, the chance of success is dramatically reduced, and it’s best to try again. Even the best seeds have an 85% germination rate. When your seedling comes above ground, it is going to want to see a direct light source.
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4) Lighting for Your Cannabis Seedling
Marijuana seedlings require a medium amount of light — enough to get energy to grow, but not too much light that to get burned. Leaving your seedling in direct sunlight will cause the leaves to curl, while too little light will cause the seedling to stretch. If growing outside, seedlings want to see a direct light source to stop them stretching. If inside, a sunny windowsill with more than half a day of sunlight works wonders. Otherwise, 24 to 30 inches from a grow light is an excellent supplement. Your seedling should not stretch more than 6 inches at most.
5) Watering Your Cannabis Seedling
For cannabis plants young and old, it’s best to use bottled, distilled, or filtered water as these are without chlorine. If using tap water, let it sit for 48 to 96 hours before watering to dissipate any chlorine. Chlorine can also be eliminated by boiling for 20 minutes. Under normal conditions, after soaking your seedling pellet, it should contain all the moisture your plant needs before it comes above ground. As it grows, it will only need about a shot glass worth of water at most per week to keep the medium damp. Seedlings don’t drink a lot of water, which makes sense given their size. Your plant will do better in a growing medium which is damp but not soaking wet. Overwatering is just as deadly as drying out!
Damping off happens when the seedling is in too moist of an environment. The young plant’s immune system is not strong enough to ward off a fungus that results in the plant rotting from the bottom of the stem. When this happens, the plant will bend over and die if not treated. To help fight the infection, lightly spray a 0.5% solution of hydrogen peroxide around the affected area. However, the best option is to avoid this by not exposing your seedling to too much moisture.
6) First Cannabis Seedling Leaves & Hardening Off
The first set of leaves to come above ground are called the cotyledons . These little leaves are packed with energy and will grow to about 1/4 in in size before eventually falling off. Your second leaves to emerge will be single blades and will be serrated, looking like regular pot leaves.
They will become several inches in length. During their growth your first actual set of leaves will appear. These are typically three blades. Around this time is when your plant is “hardening off”. You will notice that the stem will start to develop a thicker skin and harden off. As the leaves of the plant get bigger, they can gradually handle more sunlight, so move it into more direct light– the more light the better!
7) Transplanting Cannabis Seedlings
About 10 days after germination, when the baby cannabis plant has hardened off, roots will start emerging from the bottom of your seedling pellet and the plant is ready to be transplanted into a bigger pot. Be very careful not to damage the roots during this stage. Any stress will slow its growth.
Dig a small hole in your bigger pot for the seedling, sprinkle some rooting booster in the bottom of the hole then carefully plant the whole seedling pellet holding your weed baby.
Now bury so the base of its stalk is level with the topsoil. Give it a watering to set the roots in the ground, then hold off watering until you pick up the pot and it feels light in weight.
Are you ready to transplant your seedlings? Shop our best selection of Cannabis starter growing kits from small to large pots.
8. Separating the Girls from the Boys
At about 4-6 weeks into your plant’s growth , you’ll be able to determine the sex of the plant. You’ll want to separate and dispose of any male plants. This is an important step for growing marijuana because the female plants are more potent and valuable. You also don’t want male plants to compromise the growth of your female plants.
Why Do You Only Want Female Weed Plants?
Only female marijuana plants produce THC buds that are high in potency. You want to make sure your Cannabis plants are all female. If you have a male plant, it can fertilize the other female plants, and they will work to produce seeds instead of flowers and nugs.
It’s essential as a grower to know the difference between a female and a male plant so that you can remove the male plants before they contaminate your crop . Unfortunately, you have a 50/50 chance of getting a male plant when growing a plant from a seed from a nug.
There is a massive market for seeds that will only grow into female plants. But even these seeds are not a 100% guarantee you’re going to get a female plant. To ensure a good crop, you’ll want to germinate and plant many marijuana seeds and then separate the females from the males when the plants begin to show their sexuality.
How to Tell if a Weed Seed is Male or Female
As your plant matures sexually, it will develop between its nodes. Nodes are the area of the plant where the branches connect to the plant’s stalk. The distinguishing characteristics that will help you identify your plant’s gender:
- Male Plants : Small pollen sacs will cluster in the nodes.
- Female Plants : Stigmas will develop in the nodes. The stigmas can catch the pollen of male plants. Stigmas have hair-like veins that will extend from the sacs in the nodes.
- Hermaphrodite Plants : These plants have both the stigmas and pollen sacs in their nodes. These are female plants that develop both sex organs when exposed to a lot of stress.
Once you can identify the sex of your plants, you’ll want to remove the male or hermaphrodite plants because they can negatively affect the harvest of your female plants. That’s why it is crucial to germinate and grow several cannabis plants to this stage to ensure you get at least one healthy female plant.
9) Grow Weed Plant, Grow!
Suddenly, before your very eyes, the plant will transform. She will grow in height and branch out, putting off leaves and a network of branches. It is your job as the grower to meet her needs so that she can reach her full potential. With a good grow kit, this means as much light as possible and lightly watering only when she is thirsty.
This is considered your marijuana plant’s vegetive stage. The goal in this stage is to keep her healthy and allow the plant to grow as big and strong as possible so that she can hold many, many flowers.
Our complete grow kits include everything you need to go from seed to your very own supply of high grade medical cannabis.
How and when to transplant cannabis plants
Transplanting is the process of “re-homing” a cannabis plant, or moving a plant into a bigger pot with more soil as it grows bigger.
Growers typically start off the cannabis growing process by planting many seeds in small pots because they don’t know if all of them will sprout—or germinate—and they don’t know if all of them will be female.
Only female cannabis plants produce buds, so if you start growing from regular seeds, you will have to sex them out and discard the males.
Why is transplanting marijuana plants important?
Transplanting gives a marijuana plant’s root system more space to spread out, allowing the plant to grow healthy and strong and to flourish.
When roots become cramped and can’t spread out they can get tangled and become “rootbound”—this will effective choke the plant, leading to a stunted, sickly plant, and can even kill it. A healthy root system will lead to a healthy weed plant.
A plant’s container will determine how much the roots can stretch out, and therefore how big your plant will get. A container that’s too small will stunt it.
You don’t want to plant a seed in a giant pot because you could potentially waste soil if the seed doesn’t make it. Also, if growing weed outdoors, it’s hard to plan out a garden and where to put your seeds in the ground if some seeds don’t make it.
Most weed growers start seeds in small 4-inch or 1-gallon pots when germinating.
For the seeds that do make it, they will need bigger homes after several weeks of growing and will need to be transplanted either into a bigger pot or directly into the ground.
When planting into the ground, make sure not to crowd your plants so their roots don’t run into each other.
The symptoms of a rootbound plant include:
- Flimsy new growth
- Stunted flower production
- Stem discoloration (reddening)
- Nutrient sensitivity
A rootbound plant may also appear under-watered. If a plant requires watering more than once a day, it may need to get transplanted.
When to transplant marijuana
Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube .
Most marijuana plants go through 1-2 transplants during their life but could have more. As an example, transplanting can happen from:
- First container (1-gallon) to second container (2-gallon): 4-8 weeks after seed germination
- Second container (2-gallon) to third container (5-gallon): transplant 8-12 weeks later, or 2 weeks before flowering
Some growers may only transplant once: using the example above, from a 1-gallon to a 5-gallon container, skipping the 2-gallon. And depending on how big you want your weed plants to get, you may transplant into bigger pots than what’s listed above.
The same goes for transplanting outside, in the ground—you can go straight from the first pot into the ground, but it depends on when you transplant and your local climate and weather.
Here are some indicators that your cannabis is ready for a new container.
Number of leaves
Young plants sowed in small containers are usually ready to be transplanted after they’ve sprouted 4-5 sets of leaves, but keep in mind this may vary from strain to strain.
Check the drainage holes at the bottom of the container—a plant should have a healthy and visibly white root system. If roots are growing out of the holes, it’s time to transplant.
Any discoloration or darkening may indicate the plant has become rootbound and a transplant should take place immediately.
End of vegetative stage
A weed plant should be in its final pot or in the ground with plenty of room for its roots before it enters the flowering stage. During flowering, a plant will increase in both size and volume, as the plant itself continues to grow and as buds develop. It will require a substantial amount of space for root development.
How much space does a marijuana plant need?
|Plant height (inches)||Pot size|
|0-6″||4-inch (16 oz.)|
When transplanting cannabis, give the plant at least double the space of its previous container. This reduces the number of times you need to transplant and minimizes the risk of transplant shock, which may occur when a plant experiences extreme stress from root disturbance.
For example, you could go from a 1-gallon to a 2-gallon to a 5-gallon, or from a 2-gallon to a 5-gallon to a 10-gallon.
Medium-sized indoor cannabis plants tend to be fine in 5-gallon containers as a finishing pot. Large outdoor plants may require much bigger containers to reach their behemoth potential, sometimes up to 10- or 20-gallon pots.
When in doubt, always opt for slightly more space than needed. A plant tends to require 2 gallons of soil for every 12 inches of growth it achieves during the vegetative stage. Knowing the potential height of the strain you’re growing is helpful.
Why not start in the largest pot for your marijuana plant?
Growers typically transplant weed plants 1-3 times, moving plants to bigger pots gradually as they get bigger.
If a plant is put in too big of a pot, the roots won’t stretch out that much and won’t soak up as much water. This can cause water to sit in the pot for a long time, waterlogging the plant and leading to root rot.
You can transplant into the largest pot for your weed plant to avoid multiple transplants, but be careful not to water all of the soil—only water around the stalk of the plant where the young roots are.
How to transplant marijuana
Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube .
The process of transplanting weed does not come without risk. Transplant shock can be incredibly detrimental to the growth and development of a cannabis plant, and can even kill it. However, through proper execution, the process of transplanting will benefit the plant and lead to stronger root development and healthier flower production.
First transplant of a cannabis plant
Young cannabis plants should start in a 4-inch or 1-gallon pot. This starting pot should be adequate for a few weeks before transplanting is needed.
Again, the first transplanting should occur after the seedling has sprouted its 4th or 5th set of leaves. To transplant:
- Wash your hands and/or wear gloves to prevent contamination of the delicate roots, and keep the surroundings as sanitary as possible.
- Give the plant a light sprinkling of water to help minimize shock; don’t drench it, as the soil will be difficult to work with.
- Fill the receiving pot with soil, allowing enough space for the new plant.
- Avoid overpacking the soil during and after transplanting—this can compromise drainage and damage the root system.
- Do not disturb or damage the roots when transplanting; the first transplanting poses the greatest risk for shock, which can occur from root damage and agitation.
- Avoid intense light when transplanting; this will help prevent transplant shock as well.
- Fully water in the plant once it’s in its new home.
Additional transplanting of cannabis plants
You may need to transplant your weed plant a second or third time to maximize its growing potential. Always monitor plants for symptoms of distress or overcrowded roots.
To do so, follow the steps above, and make sure the new container is at least twice as big as the old one, if not bigger.
The finishing container is the final home of a plant until it’s harvested. This will be the largest container for a plant, and you always want to transplant into this pot 1-2 weeks before the flowering stage—you don’t want to disturb a plant while it’s flowering.
Keep in mind that large plants may require stakes or other support to avoid structural damage after transplanting.