Grow light position

how high should i hang my light over my seedlings?
its purple kush autoflower
my light is a spiderfarmer 1000 and ive been leaving it on the brightest


This should help you some.

Best of Luck to you!


someone told me to keep the light going 24hrs the whole time because they are autoflowers…thanks for the info, i was keeping it 12 inches over them


You can run them 24hrs, but 18hrs would be just as effective.
I’ve got a couple of autos in a tent and I’ve been on 18hrs since the beginning with no issues at all. And what I think is pretty good growth!


wow…what strain is that? how long did it take to get that big? so jealous…
they are beautiful…wish i had more room to grow…cuz i bought a bunch of auto’s…i got sour diesel, the super auto pack, purple kush and 5 feminized gold leaf…what size tent is that? 2x4?


i had to go scan through my journal to find it - They popped the ground on the 21st of November. So a little over 2 months at this point.
They’re autos - they grow fast! LOL!
I don’t even think the short one is a foot tall, but she is developing some thick old buds on her! LOL!

They’re Northern Lights. The dark green in the back left corner is a Super Skunk clone.
It’s a small Spider farmer tent, like 27"x27". In fact I’m under Spider farmer Lights, but a little bit more than you! LOL! That tent is way over powered! LOL!

It’s a long story, but I started with a SF 2x4 kit. And bought this one as a drying tent.
Then I ended up pretty much gutting the 2x4 and upgrading everything in there and suddenly I found myself light rich. I had already bought a SF-1000 to fill the footprint of the 2x4 since the SF-2000 didn’t quite get the far corners.
I ended up getting another SF-1000 in the small tent because the empty space bothered me. LOL!


I had it up to 60% and it burned the hell out of the tall girl. It’s around 50% now and she seems ok.


i had bought 2 more lights, i hung one them so far, it might be hard to see but i bought a ceiling track and used i big black tablecloth i got from work and put grommets in it and then taped some vivosun reflective panda film to it…u still got me beat on lighting…lol.
did you use any fertilizer?


would love to see ur yield when ur done harvesting


yeah, I’ve been using Jacks 321 since the beginning and some assorted microbe blends. FishSh!t, Recharge and Mammoth P… Ph it to 6.5 - add the microbes and away we go! LOL!
What are you planning to use?
If you haven’t invested yet you’ll find a lot of love for Jacks around here, though people use all kinds of things. Fox Farm is another popular choice but somewhat more finicky to use than Jacks.
Lot of organic and semi-organic growers here too.
We can surely find someone to help with about any choice you make if you need help.

edit: I’m anxious to see yields too. This is my first year growing and my first auto run ever.


Here’s my journal if you care to breeze through sometime. It starts last August and I’m the last phase of it now before I start a new grow and journal.
It covers my outdoor grow, my first tent grow and clone grow from one of those original girls, and my current auto grow. You can see why I’m starting a new journal for the next grow. LOL!

Lighting has come a long way. It’s not the same with LEDs as it was with the old high intensity discharge lights. As has plant science. Since it’s becoming more and more accepted a lot more research has been done and there was a lot to discover.
While extra lights are great for filling in shadows and corners that are lacking there is such a thing as to much light.
A lot of people are using DLI to gauge how much light power they actually need to use to grow without over doing it.
I could achieve the same DLI with just the 2000 and running it at higher levels, but I’d have some areas that wouldn’t quite get the level because of the footprint of the light , and the plant itself would create more shadows on itself!
With more lights I eliminate the shadows and even out the light “canopy” and get the same DLI with only maybe 10-15w more than one light at full blast. The goal is to fill every square inch of usable light with plant! Best use of all the resources you have.

Here’s a link to the DLI info and discussion.
It’s really not as hard as it sounds and as usual - there’s a free app for it! LOL!
I’m glad to help you with that or anything else I can! Just put a @ in front of the user name, like @4NK8, and it’ll send a notification, and I am set to watch the thread here.

Happy Growing Everyone!!!


sweet thanks for all the info…
im using these

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Welcome to the forum, it’s a great place as you can tell. Everyone above spot on, if can download photone App it’s free help u with DLI. I have Spiderfarm sfd-1000 light think I kept it around 20 inches to start seedlings.
Also I use fox farms nutes same as u, make sure you get some cal mag, and epsom salt. Also a good ph pen, and tds meter.
Lighting for autos, everyone has there own preference, when young like yours weeks 1-3 maybe or first month strait 24 hrs, then back off to 20/4 or 18/6. My theory is all things need time to rest even plants. Especially when u get to flowering stage, when its dark your tricomes produce more resin and then hopefully better buds. That my 2 cents please keep us posted and best of luck


For sure turn the light intensity down or you’re gonna burn them up.


thanks yal, im starting to cut the light off 4hrs a day, should i ease the light up gradually or just go to the same power everytime? when should i start LST? and how do i do it with fabric pots? i put a lil fan in with them…im a noob with growing, i tried years ago when it wasnt legal in my state and either my parents would find it and kill it or some douche would steal it out of my yard…lol
just used the app, my par was at 350…is that good?


You may want to pick up a timer for your light if you’re not currently using one.
Fans and exhaust pretty much good to run all the time, but the light works best on a timer.

Most people will set the DLI or whatever they’re using to judge intensity and just leave the knob alone. When the light comes on it goes to that setting and you’re good to go.
Some people ease off or up but I just set it and forget it. Most just do that too.
I figure the future of LED lighting is heading the way of apps and built in programs simulating “real” world conditions etc, but it’s not really that important. Even when reducing light hours to trigger blooming in a photo-period seed it’s gonna take the plant a week or longer to adjust to the new direction in growing whether you do it gradually or flip it in one fell stroke.

Most people will top or FIM around the 4th-6th node. Depends really on how much plant you want to train.
After the top or FIM it’ll take a few days for the plant to start sending vigorous growth to the side shoots. When they get big enough to train have at it! Generally with autos you don’t have a whole lot of time for crazy training but you can continue to nudge and shift things here and there as needed.
With autos it’s best to restrict from stressing the plant too much. They usually start moving into flower 4-6 weeks after starting to veg.
For training it’s kinda whatever works for you. There are clips and things you can buy.
I go as cheap as possible and got small binder clips from Walnutz and some solid core copper wire from Lowes. I can remember what gauge, but it’s rubber coated and easy enough to mold and bend but stiff enough to generally hold the plant down.
You can kinda see it here.

That’s Arya - my Northern Lights girl that’s hiding in the corner. :laughing:

Some people will poke a hole through the fabric, but I plan on washing and reusing the bags so I’m trying to keep them pretty much intact.

I had the same experience with neighbors and “friends” in a couple of cases I’m sure.

I more or less go by DLI and I have to check the charts every time I want to adjust the light! LOL!
TBH, I couldn’t tell you what my DLI is in that small tent.
I’m kinda blasting them a little. :rofl:

edit: Both of these girls got FIMmed at the 5th node…I think… :laughing:


I totally did not do the whole DLI thing either. I set it & forget, as well. To me, the plants getting light, & the intensity is enough for me on my dimmer to my liking.

People get way to scientific sometimes. Just sit back & watch, read your plant, it’ll tell you what’s going on. Now I don’t know cannabis very well, but I deal with plants on a daily for work. It can’t be that extremely different. Listen to @Tylersays. Dude knows what he’s talking about. :metal:t2::sunglasses::seedling:



Hey, I like that metal grid you have over your spill tray.

Where’d you get that? Or did you just make something?


sweet , i have wire and those clips on hand, thanks for all the help…i actually got a timer when i bought my spiderfarmer kit…i havent set it up cuz im off work until april…so ive been able to micro manage myself…im just impatient as a father waiting for his kid to be born…lol
i think i made the mistake of planting my first two in those 5 gallon fabric pots
as soon as they germinated and i didnt want to over water them so ive been using that spray bottle to water them around there stems into the soil about 5 times a day


They’re round bakers racks from Amazon.
They have them in about every price range. I might have paid like 8-1`0 on them. But depending on size it varies. I think these are 10"
Just search round bakers rack or round cake rack.
I’d link but there are so many choices you can narrow it down to what works best for you that way.

@4NK8 - I use everything! Bread ties, zip ties, whatever will work best but the wire is pretty easy to work with.
With autos some people do a Solo cup first then the forever home, others go straight to the final.
When watering you want to water in a ring a little bit out from the stem/dirt intersection. Too much moisture in that area can rot the stem in no time. Watering out some encourages the roots to grow out and seek the water. A spray bottle is best for the first week or so probably. .
As small as those girls are it couldn’t hurt to dome them with the bottom off a 2 liter or some plastic something. It’ll raise the humidity around the plant and help it intake water until the roots get a little more established. If you use a smaller bottle it will kinda give you a guide for you water ring also.
You can just mist the inside of the dome 2 or 3 times a day for a few days to a week and as you start to see them getting bigger leaves and shooting up a new set just ditch the dome. At that point she’s getting her footing pretty good.
Try to avoid water droplets on the leaves, it can magnify the light and burn the tender tissue and you don’t want to stress her if it isn’t necessary.
I should have mentioned the dome last night. I apologize.

Sometimes the hardest part of growing is knowing when to get out of her way!
Seedling stage is the worst! All the action atm is below the surface where you can’t see it. Once those roots get where she wants she’ll show you some love and take off growing!

Keep on strokin’! You GOT this!!

Happy Growing Everyone!!!


That close at 100% is to much freind.
I’d go maybe a little closer then the picture says and midway to whatever setting it says and snall adjustments from there if needed either way…