Grow cannabis indoors
So you’ve noticed it’s not a great time to grow outside, or growing a massive pot plant on your balcony is illegal. Fine, we can grow cannabis indoors, and we’ll be rewarded with year-round cultivation and faster grows.
First off, If you want the 101 class on indoor gardening, check out our intro to indoor growing series. You need a few things, but the most difficult to deal with is ventilation. You see, cannabis has a very pronounced smell. I describe it as “overpowering for any indoor area”. So, you need to make a device to vent the smell outside and optionally scrub the smell from the exhaust. Alternatively, you can vent into the room if you have a carbon filter to scrub the smell, but this leads to less CO2 generally, so smaller grow. Your first order of business is to find a place where you put the plant where you can attach a vent to the outdoors, or get some CO2 rich air. For an external vent, I recommend making a vent out of some rigid foam and using epoxy to attach some ducting to it. It’s cheap and you can bang out a vent in an hour.
What you need
OK, now that you have your ventilation worked out, it’s time to assemble your materials. You need:
- A place to grow next to power, and a place to vent
- A grow enclosure. You can use a tent , cabinet, or a cardboard box. Doesn’t matter. Make sure the inside is reflective or bright white, and you can get power in, has a way to take in air and exhaust it. It needs to slightly taller than the size you want to grow your plant. Stick to a 2’x2’x4′ for starting if you’re going to make something. Make sure the bottom is waterproof.
- A light. You should get an HLG 135 for this. If you can’t afford one, the Roleado 300W will work, but they are far less efficient… Granted, they are also 1/3 the price.
- A light timer.
- Your ventilation: Fan, ducting, exhaust, and optional carbon filter. A fan speed controller is also nice, but not 100% needed. Kits are available to make this easier.
- Thermometer and humidity sensor
- A small fan
- Potting mix
- 3-Gallon fabric pot, and something to go under it to catch runoff
First, we’ll transplant your seedling into its pot:
- Fill your pot 2/3 of the way with potting soil.
- Gently take your seedling out of the cup, massage the roots to break up the ball a bit, and put it in the pot.
- slowly fill in potting mix around the plant until it comes up to above the line where it was previously covered with potting mix.
- Water generously
Now you setup your grow environment:
- Setup your tent, modify your cabinet, or cut the right holes in your cardboard box for power and ventilation.
- Put your plant in it.
- Adjust your fan to get a light sway on your plant. No fan will lead to slower growth, and a weak plant.
- Adjust your light about 18″ above the plant. Set your timer to keep the light on for 18 hours a day.
- Setup ventilation. Don’t forget to have an inlet opening, and setup any filter you can on it.
Vegetative Growth Care
Once your environment is good, you’ll grow your plant to about 1/2 the final size you want it. This first phase is called vegetative growth and it represent the phase where you plant tries to grow large so it has places to put flowers. This should take 3-4 weeks in a 2x2x4 tent, but could be a week if your space is small.
You need to do the following to care for your plant:
- Check your plant daily. Look for discolorations, pests, and soil dryness. Check for dryness by touching the soil an inch below the top. If it’s moist, you’re good, otherwise add water.
- Make sure the ventilation and lights are working.
- Keep the temperature below 80, and the humidity below 80%.
- Raise the light to keep it about 18″ above the plant’s top-most part.
Once it’s about 1/3 the size you want it to be, time to flip for flower. Set your light timer for a 12-hour on-time. The maintenance schedule will change slightly:
- Check your plant daily. Look for discolorations, pests, and soil dryness. Check for dryness by touching the soil an inch below the top. If it’s moist, you’re good, otherwise water.
- Make sure the ventilation and lights are working.
- Keep the temp below 80, and the humidity around 50%. Anything over 70% is a high risk for mold.
- Start feeding nutrients once a week according to your fertilizer’s instructions
- Keep the light at 12″ above the canopy.
- Watch out for the plant turning deep green, which means over fertilization. General paleness indicates under-fertilization. Spots, necrosis, black patches indicate soil pH problems.
- Your plant will be ready to harvest in about 12-16 weeks.
As you can see, the big benefit of growing indoors is that you get product quicker, although it will be a much smaller yield that outdoors (Smaller plants, right?). However, you can get 3 crops year round, and that makes up for it. You’ve still got a lot of moving parts to watch, so stay up on it. If you want, you could put remote cameras on your (legal) grow to keep an eye on things, and just admire your hard work.
- Your plant might need support as it gets larger. It’s much easier to plan for this early rather than rigging up a hack later in life. Get some horticultural netting and attach to the grow area right above your small plant. This is called the ScrOG net (Screen Of Green) and as the plant grow through the openings, it will be supported.
- Bottom watering in the catch pan of the plant works great, and prevents you from over watering.
- Keep a humidity and temp probe in the grow chamber. Do your best to prevent mold and keep temperatures in the 60°F-80°F range.
When should you harvest
Trichomes are the little “hairs” on the plant, and they are the best indication of how ready the plant is. Check the ones coming off the buds (not the sugar leaves). If you have an inspection microscope, you can take a peek at them on the buds to see if it’s time. You should harvest when most of the trichs have turned from clear to milky and before too many turn amber.
There are two schools of thought on this. You can either take the plant down, dry it, and then trim it, or pre-trim and dry. Both work acceptably. I’ve found that pre-trimming is best if humidity is high during drying. In either case, I would highly recommend a quick trim of fan leaves before you hang your plant to dry. The fan leaves and stems are not very useful after harvest and can be discarded or composted.
Chop your plant down in the largest portions your drying system will accept. You are going to want to hang the branches in a dark place with airflow and about 50% humidity. Alternatively, you can use hanging nets designed for drying to do this part. In this case, Cut the plant into handful-sized pieces to dry and spread them out on the net.
After 4-days to a week, they will be dry and you can then begin the final trim. Get yourself a good movie or some tunes, rubber gloves, comfortable scissors, and relax while you cut off every sugar leaf to the best of your ability. This is easy, but time consuming. Make sure to trim over a bin to catch it. Those leaves are covered in trichomes and therefore THC. You can make extracts from that pretty easily. Also, all the residue on your gloves and scissors is basically hash, so… feel free to dip it all in grain alcohol to extract it and do what you will with it.
The last part is to cure your crop. Now that you trimmed everything, break them in to smaller pieces and put them in sealed jars. You want smaller jars so that if a jar gets mold or goes bad, you don’t lose the whole crop.
You will let them sit in these jars for about a month. Open them once every few days to release moisture. If you’re in a dry place, you might want to had some humidification packets to the jars. They prevent the buds from getting too dry.
Now you should have a good starting point on your journey. Make sure you look through our articles that might be a good resource for you, like:
If you have any questions, have any suggestions for what you’d like to see in future articles, or want to have us help you in your home grow, contact us and we’ll be happy to help out.