Well this may be the last message from this OP. I think my grow is finished due to several missteps. All I can do now is learn from the mistakes. What a humbling experience…
It’s been three weeks since planting and this is what the seedlings now look like. Leaf-burned, either under/overwatered and just plain stunted. I’m not going to bother with a picture of every plant but below is representative.
Below are a few more photos of what I would consider to be the 3 “healthiest” seedlings along with a view of the root system of the first plant shown at 3 weeks.
Dog Patch #3
Hashplant 1 #3
OG Kush x Puck bc1 #2
Dog Patch #3 roots
I’ve searched for examples of what seedlings should look like at 3 weeks and none look like these. Maybe these are healthier than the first set of photos but all still have really stunted growth. Multiple sets of leaves present (after the first burned set) but struggling to grow leaves into multiple-fingered examples with true noded branches. Perhaps the last two seedlings above have started such branching, but weakly. Also, the root growth also looks weak compared to healthy seedling examples where the roots are growing out of the drain holes of the solo cups at 3 weeks.
So, how did things get off track? Below is a sort of post-mortem by each growing input with my thoughts. I welcome yours if you have the time.
Light
I was using a 630-watt dimmable LED in a 4x4 tent. I started at 30% output 30 inches away. After 4 days from the seeds going above ground, I noticed some yellowing of the cotyledons so I turned it down to 25%. Then, beginning to worry about slow growth, after 8 days I started increasing the output. I increased output so that by day 14 lights were at 75% output. I also moved the lights closer so they were 24 inches away from the seedlings. I think 75% output at 24 inches burned them. As can be seen above, most of the cotyledons and first sets of leaves were burned, though additional leaf sets continued to develop in a stunted way. However, burned cotyledons and first leaf sets can’t be a good sign for future development. I have tracked down a phone app called Photone that many reviewers say provides accurate PPFD readings compared to spending hundreds for an actual meter.
Environment
In terms of environment, temperatures ranged from 74-75 degrees to 84-85 degrees F and relative humidity ranged from 45%-60% depending on time of day. Ambient conditions exert some influence on these values. I do have the ability to cool and increase RH to a degree but don’t have the ability to “program” temp and RH to exact degrees and maintain them constantly like a Pulse system if tighter ranges are needed. I didn’t use domes in the initial first days fearing damping off.
Growing Medium
I was using Pro-Mix HP, but with no perlite or dolomite lime amendments to it like many do. Never having used a soilless medium, I’m not sure what I might be doing wrong working with it but regardless next time it’s going to be amended with perlite. The Pro-Mix HP seemed very dense and cakey even though it’s supposed to promote drainage more than other Pro-Mix blends. Nowhere close to the “dirt” I’m used to working in the yard.
Watering
I weighed the solo cups filled with the wetted Pro-Mix HP just after planting the seeds (about 325 grams) and then waiting until the cups pretty much dried out and weighed about 160 grams before the next watering. Like a wet-dry cycle approach, which may be totally wrong for seedlings. With this method I watered them for the second time about 6 days after planting the seedlings. They received a third watering this weekend same way. Is this too long to wait? I searched online for videos showiing waterings of seedlings in solo cups and couldn’t find any examples. Each solo cup had several drainage holes but there was never much runoff from any. This is because I was afraid of flooding the cups (overwatering). I used distilled water from a condiment-type squeeze bottle. Never thought it would be so complicated. Simply put, given the growing medium I’m using and the size of container, is there any way to quantify the ideal amount of water seedlings need? Somewhere folks were stating 100mL for seedlings in solo cups. I feel like with perlite added to the Pro-Mix HP I’d have to water more often, but maybe that’s not a bad thing.
To be clear, I never watered the seedlings by misting, fearing leaf burn arising from droplets settling on leaves (almost a magnifying-glass effect). I know this goes against how many folks water at this stage – could never misting them have been a problem? One thing about misting that I’ve never seen addressed is, how long in the seedling’s life until you actually start watering the soil?
Nutrients/ph
I was told no nutes for 2-3 weeks. The seedlings have never received a feeding. I was afraid to stress them with feedings at such an early stage. But at the same time, I read that soilless mediums like Pro-Mix need more nutrients than actual “soil” mediums so that has me thinking maybe they did need nutes. Also, I have Botanicare nutrients. Are these the wrong type of nutes, since Pro-Mix is actually a soilless medium? Should I be giving them hydroponics-type nutes instead? At this point, should I at least try one feeding at 25% strength to see if it helps?
As for pH, I was told Pro-Mix HP would not need any pH amendments. I also didn’t realize Pro-Mix has a hydroponic-like ideal pH range of 5.5-6.2 since it’s soilless. As I said up to this point no nutes, just distilled water. Not a lot going on I’d think to dramatically alter pH, though I know the breakdown of the peat in Pro-Mix will lower pH to some extent. As I stated earlier none of the solo cups would generate much runoff after watering, so measuring pH of the runoff would have been tricky.
So that’s my download…any opinion or tips would be welcome. Just hope I do better next time!