Hi all, I need a little help and advice from those versed in using light measurement to grow autos. My problem is basically, very short, squat plants and zero stretch at flower. I veg with light at 18" above canopy and when flowers appear, I drop light down 1 inch a day till it reaches about 11/ to 12"". I was assuming that as my plants werent growing in height, that my light was too weak and so moved it closer. Now Im beginning to think that maybe my lights are to powerful in my little tent 60x60x140 tent (only 170W) and / or Im bringing them too close to fast. I havent had any light burn, well not up to 10" away but I havent dared go closer. Does anybody have a DLI chart or a PPFD chart for autoflowers to give me something to aim for, or give me any pointers would be much appreciated.

I've been doing a fair bit of reading on lighting for cannabis, as I was concerned my plants were not getting sufficient light. There are a lot of resources out there, but most are dealing with photoperiod plants, very few cater to autoflowering varieties, which are not flipped but stay on 18/6, 20/4 or even 24/0 throughout. Also most information assumes a tent like setup of at least 4 sq. feet, with lights hung between 18 and 36 inches away from the canopy. I'm growing in a small cabinet, the floor area is approximately 3 sq. feet (0.28 sq. metres), and the distance from the top of the pots to the lights is only around 22 inches (55 to 56cm approx.). As a result I'm finding it tricky to estimate what the optimum PPFD for my plants should be. I've been using an Android app to take measurements, but depending upon which LED profile preset I use, I get different results. So I'm still not clear if I have the right light intensity for my small space. If anyone with more knowledge could advise, that would really help. Some data below. --- Autoflower plants, currently entering week 3 of flower. 20/4 light schedule. Main lights: 2 x 60w LED panels, "blurple" (percentage is 74/26 red/blue) with smaller numbers of white, orange, UV and IR LEDs also. PPFD readings at the canopy are 570 umol/s/m2 using the red/blue preset, 286 umol/s/m2 using red/blue/white preset. Lux reading is 5600 approx. at the canopy. Side lights: 2 x 18w daylight 6500K LED wall panels, with 36 white LEDs each. PPFD readings at the nearest plant are around 56 umol/s/m2 using Low CRI LED 6500K preset. They are rated at 1500 lumens each, and the lux readings are roughly in line with this close to the lights. Total wattage at the wall is 156w, which gives a an estimate of 52w per sq. foot, or 557w per square metre. As I'm using side lighting there might be some variation there. ---