First homemade grow box, plants started drooping

Hi friends!

So I have these "weed in a can" kind of things going on here, but after I bought them I realized I wouldn't be able to provide sufficient light, as my flat is south-faced.
I started researching on homemade grow boxes as I had big cardboard box from my PC case, so I ran to the hardware store, got some supplies and ran home
and started building! It measures 10"x21"x25", so not that much space, but I hope I can grow my plants short enough to fit. I'm using 6500K daylight CFLs for veg and 3500K warm white for flowering if I ever get that far...
I've already run in to a few problems, which I hope someone can help a wee bit with.

1) If I close the door and don't have the huge fan running in the back, it will easy become 36-38° in there. With the door open and the fan running in the back I can get the temp down to around 27-28°. As you can see, I already tried cutting various holes to try and get temp down. Is there anything else I can do to get the temp down a few degrees?

2) After I put my plants inside the started to droop and become kind of wrinkly looking. Before I had them under a 40W LED where they seemed to be having a decent time, with straight leaflets and all. But I don't know if they are now getting too much heat, or what's the deal. I can water them every days, and doing so with 100ml tap water with a few drops of Biobizz Grow. I've only started giving them nutrients 1½ week ago, so don't know if it could be that.
I do not pH up or down. Should I go back to straight water?

Any help and advise is greatly appreciated <3

You state that you can water every day... that is likely your issue, those cans are long in profile, and I would be willing to bet the bottom half is still soaked when it comes to the next watering. roots dont like that, and it can take a few days for issues to start showing issues. Back off on the water, and share some data around your temps, PH and neut feeding if you can - helps build a better picture of whats happening.

Woops, I meant I can water them every 2 days. I do some thourough logging and weighing them as well and can see that they have drunk all the water I've given them.
I dont have the pH value of the water I'm giving them sadly, but I've been told that using Biobizz Grow (1ml per 1 litre) in day-old tapwater should bring thepH down to approx 6.5.

I still have my suspicions on over-watering, they just look soaked. You are right about BioBizz bringing down the PH a touch, but its just something you should never really leave to a guess. The basic test strips are cheap and give you a great idea of whats happening. If you cant get a test kit, try to get some spring water (bottled) where you can check the PH (on the label) - 6.5 is a nice safe bet. Make sure to give em a flush every so often too, as feeding on each and every water is usually overkill. Or switch to a foliar for a week, and give the soil a chance to flush

I was suspecting overwatering too. I will get some pH testing kit then and check this as well. Thanks for the help bud!

Without a doubt your overwatering. Let the soil dry out watering every other day is good or even leave a couple of days if temps are low and RH is high.

The temp in teh box is around 28C and humidity a stable 50%, except at night where its between 60-70%. But I will definitely water less, seems indeed like this is the issue! Just figured it might be the heat or the CFL's

Looks like over water & maybe too much heat. Reminds me of my 1st grow box. Made out of a mini fridge.

Do those cans have holes to drain at the bottom?

Yeah there's plenty of holes there, but i dont see any excess water coming out unless I give them more than 100ml of water. I had one of the plants out to test under a LED and it seemed that the leaflets started to straighten out a tiny bit. If heat is a problem, should I raise the CFLs and lose a bit of kelvins? Or reconstruct the box to get more cold air flowing and expose them to a tiny bit of light during the night? The strains are Zkittlez, gorilla and glamour, all autoflowers, grown july 25th, july 30th and august 8th if thats any help

What is the size of those cans volume wise? It looks like they are going to outgrow those pretty quickly, and the lip on those things looks like its going to make popping them back out for transplant a challenge.

I believe they are about 2 litres or so.
I'm a first time grower, so figured these cans would be a nice way to start learning without making further investments in equipment. They are indeed not intended for training etc, and I dont believe it is necessary to transplant before flowering. Small can, little plant, small yield kind of deal there. But should I want to transplant, I can easily cut off the bottom and and do so.
But that whole idea with the little grow box I made is that it can fit 3 small plants.

McStankface said:

I believe they are about 2 litres or so.
I'm a first time grower, so figured these cans would be a nice way to start learning without making further investments in equipment. They are indeed not intended for training etc, and I dont believe it is necessary to transplant before flowering. Small can, little plant, small yield kind of deal there. But should I want to transplant, I can easily cut off the bottom and and do so.
But that whole idea with the little grow box I made is that it can fit 3 small plants.

Click to expand...

You definitely can make it work, just going to be a lot of work, as there is just not going to be any nutrients left in the soil in another few weeks. So you will need to be constantly adding liquid nutes to your watering your entire grow. At that point you might as well do a DWC coco or a hydro grow which would take better advantage of the small pot size, and be easier to dial in your nutrients. Using soil as your medium makes that a little trickier.

I have definitely seen some really cool microgrows so I know its possible, just a lot of work doing it all by hand and in soil. To be clear I grow in living organic soil, and definitely prefer that over hydro or bottled nutes. I just am not sure how you could do that in a tiny grow.

ilovereggae said:

You definitely can make it work, just going to be a lot of work, as there is just not going to be any nutrients left in the soil in another few weeks. So you will need to be constantly adding liquid nutes to your watering your entire grow.

Click to expand...

I am prepared for this as I figured water only wouldnt be sufficient all the way through, so got Biobizz Grow, Top Max and Bloom at hand and will following the schedule made by Biobizz.

ilovereggae said:

you might as well do a DWC coco or a hydro grow which would take better advantage of the small pot size, and be easier to dial in your nutrients. Using soil as your medium makes that a little trickier.

Click to expand...

This I am definitely considering for my next micro grow project, I just need to educate myself on this before venturing into more advanced growing methods haha.

Quick update, I didnt water the plants for 3 days, and so yesterday I only gave them approx 50ml of water with no nutes. Also made the drain holes in the bottom slightly wider for easier flushing.
It was definitely overwatering. Side by side comparison


Also made the drain holes in the bottom slightly wider for easier flushing.
Thanks for the help and advise!

McStankface said:

Quick update, I didnt water the plants for 3 days, and so yesterday I only gave them approx 50ml of water with no nutes. Also made the drain holes in the bottom slightly wider for easier flushing.
It was definitely overwatering. Side by side comparison

View attachment 4663036View attachment 4663037
Also made the drain holes in the bottom slightly wider for easier flushing.
Thanks for the help and advise!

Click to expand...

Yeah that's looking a lot better

McStankface said:

I am prepared for this as I figured water only wouldnt be sufficient all the way through, so got Biobizz Grow, Top Max and Bloom at hand and will following the schedule made by Biobizz.



This I am definitely considering for my next micro grow project, I just need to educate myself on this before venturing into more advanced growing methods haha.

Click to expand...

Hey Bro, when you start the Biobizz nutes try starting out with half strength feeds and then move up strength depending on how your plants react. I've used Biobizz nutes for many years and even though they're Organic they can still burn a plant. I've got a Green Gelato in an 11l pot in soil, half way through Flowering and even half strength is a bit much for her. Hope this helps. Cheers

IndoBlazing76 said:

Hey Bro, when you start the Biobizz nutes try starting out with half strength feeds and then move up strength depending on how your plants react. I've used Biobizz nutes for many years and even though they're Organic they can still burn a plant. I've got a Green Gelato in an 11l pot in soil, half way through Flowering and even half strength is a bit much for her. Hope this helps. Cheers

Click to expand...

Duly noted! Thanks for the advice man

South facing windows are bad? You must be in the southern hemisphere?

Plan for success. I think you're going to run out of space so .. while they're small, start looking for a larger box.
Probably 1 square foot per plant and if they grow to around 18" like most regular autos do, you need room for the pot 10"? the plant 18" and your fixtures which currently look to take up another 8-10" so I would look for min 40" tall.
If any of those strains are super autos, they can get twice as tall.

Also, and this is just an idea, if you were able to get the socket and plastic base of the bulb itself outside the box, you might reduce your heat a bit because there is a small transformer inside the plastic base of the cfl bulb that generates some heat. It might only make a 1 or 2 degree difference but every degree counts.

For reference, I've attached a picture of my cheese autos in late flower inside a 20"x30" space. And I should tell you that they were attacked by root aphids, underfed and stunted so they should have been bushier. The tallest was just over 18" when we chopped her.

South facing windows means I wont ever get direct sunlight, hence why I've resorted to the grow box there
I think its very likely I will run out of space, but thats why im trying to control the height with hanging the bulbs next to the plants rather than above them. I do think its a good idea to install the sockets outside the box, it would solve some heating issues for sure. But then I dont think the plants will get enough light. Or will it have an impact having them to hang 15" If they grow to around 18" then for sure I would have to have the sockets outside the box anyway as I have 19" from the medium to the ceiling. But I could do some modifications and add an extra 5" to the height there