Winter has arrived and it’s time for indoor grows to shine! Temperatures drop and it’s much easier to keep up the right parameters in your grow, both heat-wise and in regards to humidity. It’s time to germinate your seeds and harvest that grow in three months’ time – learn the secrets to indoor growing with this article.
The first thing you need to give some serious thought to is the strain that you’re planning on growing – you want to find a strain that has the characteristics you want and that adapts to the space you have available to grow in. You can go check out the hundreds of strains we have available on our webpage, all of which have complete descriptions made by us from our point of view. How much your plants yield generally has a lot to do with the potency of the light you’re using – a 250w light will under no terms produce more than 150g, and a 400w light will find it hard to produce over 300g from your plants – with 600w bulbs you can get 500g per square meter of light.
You’ll need to know exactly the space you have available and your budget; it doesn’t matter how many plants you grow, the yield will always depend on the kind of light you’re using – if you plant 10 cannabis plants under a 250w light, you’re not going to get 50g from each one. You’ll end up with 15g plants, and those 15g will be spread over horribly tall, long plants, and the bud will practically be like smoking straw. You need to adapt to what you have – if you have a 250w light, don’t try and plant more than 4 seeds; if you have a 400w light don’t plant any more than 6, and if you have a 600w light don’t plant any more than 12. This, of course, applies specifically to growing from seeds. Sometimes if you plant too many plants you’ll end up losing a lot of yield as well as quality – it’s always much better to plant less and get more yield and more quality.
To know exactly how powerful the light you need is, you need to take into account various factors such as the space you have available, the amount of cannabis you want to produce and if you want to have enough to last you until the next grow – which is also another factor, because you’ll want to produce more if you’re only going to grow twice a year. You need to measure the space you have and based on that, pick your bulb.
- 250w: 80x80x160cm
- 400w: 100x100x200cm
- 600w: 100x100x200cm with a cooltube and 120x120x2m with a normal reflector and a decent extractor.
- From 120x120x200cm onwards you can place one 600w light per square meter of grow – if you place a 2mx1m tray you’ll need two 600w bulbs to get the best yield possible; if you were to use any less, you’d get a lot less yield and the quality will be quite bad.
If you don’t have available space to put up an extraction system and reflective sheeting on the wall or a place you can easily close, you can get a grow tent where it will be much easier to control the parameters in your grow so that your plants grow properly. You can calculate what kind of extractor you need in our article all about air extraction.
Now you’ll need to find the right substrate depending on the humidity in your grow, the kind of seed you’re planting (autoflowering or feminized) and the amount of fertilizers you’re planning on using. Some substrates already come with growth nutrients and flowering nutrients, and others are considered “light”, and then there’s substrates that retain a lot of water and substrates that don’t retain much. You’ll need to pick the right substrate depending on your grow conditions – don’t just buy because the price is right. If you’re not sure which to pick you can use one with a medium water retention such as Top Crop’s substrate. After your first grow it will be much easier to know if you need one that has higher water retention or lower as long as you’re growing in the same place.
When your grow area is ready, whether you have a grow tent or not, you need to germinate your seeds to begin the actual grow. You can use our seed germination system, as it’s practically fool proof. Once they’re all germinated you can start putting them in flowerpots. You need to put them in small flowerpots, full of the substrate that you plan to use – make sure it’s been previously watered. When putting the seed in, make sure the root is facing downwards. Now you can place them in your grow tent or room. I tend to give them 24h of light in this first stage with the lights up high, and once they pop out you can switch them to 18h light with a timer.
After a few days you’ll notice that they’re stretching upwards, and sometimes they get stuck growing and don’t go any further – this is a sign that you need to transplant to the next pot. If they’re autoflowering plants you can plant them straight into a 7L or 11L pot. If they’re seasonal plants then you need to start them off in 3L pots and then transplant to 7L at this point. We’ll explain this in more detail later.
For the vegetation phase of seasonal plants, you’ll need to have them at 18h of light a day, and if they’re autoflowering you can set them to 20h for their entire life cycle. You need to try and make sure that the maximum temperature at the top of your plants with the lights on is 25º and 20º when they’re off. The best way to organize this is to have the lights off during the hottest hours of the day and have them on through the coldest hours of the night, so that the outdoor temperatures can help regulate the indoor temperatures.
The fertilizers you give your plants need to be rich in nitrogen, and they’re generally called something “grow” such as Bio Grow, Solotek Grow, A+B Grow… these fertilizers are perfect if you want some strong, green plants with strong and resistant stems and trunks that will be able to put up with some hefty buds.
Once it’s been about 20-25 days, it’ll be time to flip your plants over to flowering lighting, but switching the timings to 12h on and 12h off. By reducing the amount of light your plants get you’ll induce the flowering process that generally happens when days get shorter in the summer, and in about 10 days you’ll start seeing little pistils on the flowers. When you flip them to flowering times, you’ll need to transplant them to their final flowerpot, and around 7-11L is generally enough for indoor grows. If you’re growing organically, then now is the time that you’ll want to add some bat guano to the substrate for the fattening period, which will be absorbed within about a month. If you’re growing using chemical or mineral products then you can use a flowering stimulant alongside your growth fertilizer to grow as many flowers as possible which you’ll later fattening using other products.
Once your plants begin showing their sex through flowers underneath the lower leaves then they’ll begin flowering soon. This is when you’re going to need to switch the vegetation nutrients for flowering nutrients and keep using a flower stimulant until you see that buds have formed on the tops of the branches and all along the central stem – when this happens you need to stop using the stimulant and start using sugars to fatten those buds.
Sugars will give the buds density and much more resin while they’re still growing – this ensures that your buds won’t end up soft or too airy. It’s also so that when your buds begin the fattening phase they have sugars to fill those fat buds with, making for harder, heavier and more resinous flowers than if you were to not use sugars.
After about 35-40 days since flipping the lights, the fattening phase will begin. This is when your plants start asking for a bit more than what a normal fertilizer can give them – they need an extra dose of phosphorus and potassium. You can give them something with a high PK, like Bloombastic, Monster Bloom, Blossom Builder or any other products like these alongside your normal flowering fertilizer. If you’re using organic nutrients then now is when your plants should begin absorbing the bat guano that you used a month ago which will give it a high, natural PK boost and all you have to do is keep using your fertilizer nutrients. Make sure you have control of the dosage as you could run the risk of over fertilizing your plants. After about three weeks the buds on your plants will have changed quite a lot, they’ll be thicker, harder and the little white pistils will stop appearing and turn brown, which is a sign that your plant is maturing and that you should flush the roots and harvest soon.
When it comes to flushing the roots you don’t really need to do much; I simply water them with plain water for the last 10 days before harvesting until the leaves begin to get yellow, which is a sign that there’s no nutrients or salts left in the soil or the plant itself. There are products such as Flawless Finish, Final Flush or Canna Flush which can help you shorten the flush time by getting rid of the nutrients left in the soil and the plant.
Once the plant begins losing color, you’re going to want to harvest it. Let the soil dry out completely before cutting it down, as if your plant still has a lot of water in it, you run the risk of rot when attempting to dry it. If you’re in a humid climate you’ll need to remove all of the leaves, large and small, and place the stems upside down in a place where it’s not too cold with some airflow – if it’s really humid they can take 20 days to dry completely, and if you can you should remove any stems and place the buds on a drying rack or at least hang them branch by branch rather than the whole plant at once. If you live in a hot, dry climate then you’ll need to hang the whole plant, leaves and branches and everything so that it doesn’t dry up much too quickly or the chlorophyll in the buds won’t evaporate properly; the chlorophyll is what gives buds that green, grass smelling like aroma.
Once they’re dry all you have to do is cure them, which will improve the quality of the buds quite a lot, as well as the high that you’ll get from them. If you want to read up on drying and curing cannabis, have a look at our article on the subject.
Once the curing process is done, all that’s left is to enjoy the weed and prepare your next grow, getting better and better each time! Welcome to the world of indoor cannabis growing!
Author: Javier Chinesta
Translation: Ciara Murphy