Hello everyone, I need advice. If you would be so kind as to help me, could you tell me, how feasible is it to cultivate an autoflower indoors but with natural light? My plan is in a spare room where there’s a lot of natural light and it’s well-ventilated. I don’t know if I would have much trouble since it’s not direct sun nor is it outdoors, so I’d like to know if anyone has any advice on whether that would be a good idea. Thank you very much.
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Growing indoors by window light is possible but won’t yield much and it’ll be lower quality. The glass filters the light and blocks things like uv. Even with 8 hours direct light coming in a room it won’t be enough. It can be a learning experience. I’d suggest buying a used setup off fb marketplace. It’s illegal in my state and marketplace is flooded with used and new setups. Whatever you do the light is the most important part of the grow next to using good genetics. You can scrape by with a cheap tent, exhaust fan and circulation fans.
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I would say you should get a light to help bc like Blunt said glass filters the light. Not only that but it also cuts down on the amount of light that comes through. A light would make it easier for someone starting out. A window only grow would be slow and the plant would be spindly. Your yield would be very little for the effort put forth. You can pick up a new 150 watt light for about $100. A tent is another thing that helps with growing indoors.
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@Demonrage75 the thing is it’s a well-lit room, with the window always open, and there are some hours of sun in the afternoon, should I still put some supplemental light on it? and if that’s the case, is an LED bulb enough? at what height should I place the light above the plant?
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Let’s be real: you can totally keep the plant alive, but just using indirect natural light indoors probably won’t give you a big, awesome harvest.
Here’s why, what to expect, and how to make it work if you still wanna try.
The Main Problem: Light Intensity vs. Light Time
Autoflowers are cool because they don’t need a dark period to start flowering. They just flower when they’re old enough, which is great. But people often mix up how long they need light with how strong that light needs to be.
Duration: Autoflowers love a lot of light – usually 18 to 24 hours a day is best for a good yield. A window will only give them whatever daylight hours are happening outside.
Intensity: This is the real kicker. Glass windows actually block a ton of the specific light spectrum (and strength) plants need to grow. Indirect light (just the general room light, not direct sun on the leaves) is unfortunately super weak for a cannabis plant.
What happens to a plant in indirect window light?
If an autoflower doesn’t get enough strong light, it’ll probably:
Stretch: The stem will get really tall, thin, and “leggy” as it desperately tries to get closer to the window.
Grow airy buds: Instead of dense, thick buds, the flowers will usually be very light, leafy, and “popcorn-like.”
Yield very little: You might end up with only a few grams of usable stuff after months of taking care of it.
How to Make it Better (If you still wanna try)
If you have an extra seed and just wanna do a fun, low-risk experiment to see what happens, go for it! To give it the best shot, keep these things in mind:
Direct Sun is Best: Move the plant as close to the window as possible. It needs to be directly in the sun’s path for as many hours a day as the room allows. South-facing windows are usually the best in the northern hemisphere because they get the most consistent sun all day.
Add a Small Light: If you notice the plant stretching or looking weak, even a pretty cheap, low-wattage LED grow light hung right above it can totally change things. It fills the gap between the weak indirect window light and what the plant actually needs.
Watch the Temperature: Since you said the room is well-ventilated, that’s a huge plus! Just keep an eye on the area right next to the window glass. It can get surprisingly hot during peak sun or cold at night, which can stress the plant.
It’s a fun project if you go into it without high expectations, but if you’re looking for a successful, big harvest, adding even a small dedicated light source to that spare room will make a huge difference.
Hope this helps 
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Would it be possible to place the plant in front of instead of behind the window? Do you have a windowsill outside the window? This way, the pane would not weaken the sun’s rays.
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@herr_gruen the window is always open; in this room the window has never been closed 
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Then there won’t be a pane there to weaken the sun. But I would still consider the idea of an additional lamp that @Nicklovin420 had in order to get a reasonably decent harvest.
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The lamp idea sounds good, but I have no idea what the lamp should be like, its power, or how to place it. The seed I have is a gift (Auto Mimosa Cocktail XXL) and I don’t want to waste it, but I also can’t afford a grow tent.
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Look up full-spectrum LED lamps online; there are also some with sockets like light bulbs. 60 watts should be more than enough as supplementary light. You might be able to hang these over the plant with a hook screw, and they should be relatively inexpensive.
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Can you grow outside?
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yeah, that’s the question everyone is surely asking, the thing is that on my balcony the plants can be seen from the building across the street, I live in Spain, it’s not illegal to have a plant for personal consumption but it makes me uncomfortable for people to see it (although I’m still considering that possibility) besides, right now the plants I have on my balcony are suffering from a pest of these small flies that get underground, so I don’t know how that could affect the plant. I’m considering many possibilities without having to resort to a grow tent because I can’t afford it.
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These flies are probably fungus gnats, an absolute pest. You can keep them in check with predatory mites and nematodes; if there aren’t too many yet, you can also get rid of them that way. Some neem oil in the water when watering could also help against them, but that is harmful to soil life.
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Definitely sounds like fungus gnats. Any product containing BTI like mosquito dunks will work to eradicate them and not harm the soil life. I use Wdg3000 as it’s the highest concentrated for available to me. There are different products depending on the country.
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mosquitas de la humedad or moscas del sustrato 
Since the lifecycle happens both in the air and in the dirt, you need a two-pronged approach to get rid of them completely.
Let the soil dry out: Fungus gnat larvae need constant moisture to survive. Letting the top 2 inches of soil completely dry out between waterings will naturally kill off a massive portion of the eggs and larvae.
Target the larvae (The Soil): you can water the plant with a mixture of 1 part 3% hydrogen peroxide to 4 parts water. It fizzes up in the soil, killing the larvae on contact without harming the plant, and breaks down into water and oxygen. Alternatively, look for a biological larvicide containing BTI (Bacillus thuringiensis israelensis), a natural soil bacteria that specifically targets gnat larvae.
Target the adults (The Air): Placing yellow sticky traps (trampas cromáticas amarillas) right at the soil level will catch the breeding adults before they can burrow back down to lay more eggs.
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An inch or two of sand on top of the soil will help get rid of them. It keeps them from digging in the soil and breeding. Lost coast plant therapy is good for most pests.
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I found sand useful too in combination with a daily spray of a weak solution of neem oil and dish soap for about a week
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