Hello, first post and first indoor project :)

Hello there, I'm just a dude who got tired of spending crazy money on shitty weed, and decided to make a small box to grow my own plants.

The box will be about 20x28 inch and 60 inch high, and I hope to be able to grow 3-5 plants in there.

I have calculated that for that area I would need approx 12000 lumen light, and such small lights are unfortunately not available, the 250W HPS lamps I found are 19000+ lumen, so I decided to go with mini fluorescent lamps, those with the integrated electronic ballast.

I decided to use 8x18W 1200 lumen lamps on the top (total of 9600 lumen) and 4 more in each corner of the box, totaling at 14400 lumen, I think it will be better for the lower side branches if there is light also coming from the side, instead just from the top.

So overall - 216W, 14400 Lumen, about 60$ total cost, no ballast/starters needed

For the growing pots and medium I decided to go for about 7 liter pots, according to the info I got I calculated 7 liter pots will result in about 40 inch high plants. For the medium I have chosen keramzit (I am not sure about the word in English so I post a pic also)

I have chosen this media mainly because it is reusable many times. Since there is no plant food in this medium, I will be adding fertilizers to the water.

And here come my questions.

I've decided to make a simple watering system, that will keep about 1/3 inch of water at the bottom of each pot all the time. I don't know if this is such a good idea, but I think this way the plant will get as much water as it needs, anytime it needs it. My main concerts are 2:

1 - will the plants have problems being kept in moist medium all the time, cause I read plants should be watered every 2 or 3 days
2 - as the medium has no food in it, will that material be able to absorb and transport the food I put in the water, if water is supplied to the bottom, and I rely on the medium to transport water and food up to the very top

For feeding the plants I have chosen the dutch formula fertilizers plus the additional minerals and root stimulator stuff. Will this be enough for the plants or they will need more/different food?

The pots (actually mineral water bottles, chosen for having a small top, thus evaporating less water) will have many holes to assist getting fresh air to the roots.

For cooling and air circulation I've decided to go with 2x5.5inch fans at the bottom, that put air in a small space beneath the base of the plants, the base itself will have some holes and the cool air will come from beneath the plants and go up in the whole volume of the box, leaving no places without ventilation and equally decreasing temperature. There will be another fan at the top that will exhaust the hot air from the box outside.

There will be a clock/thermo regulator device that keeps temperature in reasonable levels - during the light cycle it will start the cooling fans as soon as the temperature reaches about 30 degree and stop when temperature goes down to 26-28. I have read that temperature should be lower during the dark cycle in order to simulate the colder night, so during the dark hours temperature will be kept around 24 degree.

During the winter it is possible that ambient temperatures will be lower, and I might install a second thermostat and a small heater (cheap hairdryer) in order to keep temperatures falling under 21 degree. The whole box will be thermally isolated from the outside, but still there might be some cold passing through the fans. Regular air goes up when hot and down when cold, so there shouldn't be much cold air entering the box when the intake fans are not running.

In general, I wanted to make the box to require as less care as possible, thats why I decided to go for that watering solution, it will keep much water, and I will only need to add some a few days or so. Light and temperature will be controlled by automatic timers.

So, I would like to know what do you guys think of my idea, if there are weak points and room for improvements. I will also attach a rough drawing of what the box will be like:



Hope I get some useful info and ideas before I start building it this weekend

Driver --

I see a few issues with your setup:

1) You will probably never need a small heater to warm the space up - period. I thought that as well when I first started growing, but in the entire time I've never once worried about temps getting too cool. The problem you're going to have is cooling not heating.

2) The medium you've chosen to grow with -- keramzit -- its called Hydrotron here in the states. Yes it is reusable but must be sterilized between uses. This is a huge pain. For a small operation like yours, it would be manageable.

3) You will have to change the water out once a week. You can add plain water to the system for a while, but it will become more and more difficult to maintain the correct PH with the correct mix of nutrients in the solution. This is because the plants will be pulling nutrients out as they need them. So, pretty soon, you start to have key deficiencies in the makeup of the nutrient solution. Topping off doesn't help because you begin to have salt and mineral buildup in the solution anyway. And, changing the solution helps to keep algae growth to a minimum.

4) Your box is dependent on everything working perfectly all the time. This isn't going to happen. Perhaps you should consider a simpler setup -- like little pots with dirt in them. Have you grown flowers in a window box before? Or did you grow a little plant in elementary school? Start simply and learn learn learn before you take the big step and jump into hydroponics.

10x for your response

the problem is the room I plan to put the box in is not too well heated, and winter is coming. During winter temp in that room is about 15 degree, and sometimes, when I am away from home it drops to 6-7 degree

the time I have to switch to 12/12 light cycle will be somewhere in the end of January - the coldest times, and temperature could easily become as low as 5-7 degree, and 12 hours without lights and an outside temperature of 5-7 degree will most probably kill the plants

I have grown some pot previously, in soil on my balcony, and inside near a big window, and my concern is that the pots become bug farms, as nowhere near the plants bugs can find better conditions, they go to the plants, where it is warm and moist. Last year I got thousand of bugs, and some tiny white worms in my soil. I suspect the soil I buy from the local shop already has the bugs eggs in it.

I had to rethink lightning yesterday and I came with a higher lumen output solution.
I decided to go like this:



On the top I will put 8x23 watt 1500 lumen lights, that I will use until entering the flowering phase, and the I will add 4 additional 22 inch 24w 2000 lumen lights in the four corners of the box. That will give me 12000 lumen on the top, and 8000 more lumen for the lower side branches, total of 20000 lumen. I could also go for a single 250W 20k lumen HPS light, but it will output more heat, and light distribution wont be that good IMO.
I plan to put inside as many small plants as possible, in order to get 4 females, I planned the box for 4 plants. Last year I got 4 females out of 14 plants, so I wont rely on good luck, and plant more seeds, if I get more than 4 females, I can chose only the best 4 plants, and get rid of the rest, or give to some friend to take care of.

I have also given up on the watering system, and will water the plats manually. I guess I won't have longer than 4 day holidays during the winter, so I will be around to water.