I'm using a super soil mix that I mixed myself off of a recipe from someone on Youtube. It was aged at least three months before use. I'm adjusting my water to Ph of 6 and growing a few different autoflower hybrids. I collected the small bit of runoff from the grow bags after watering today and tested that runoff water that percolated through the super soil. It's testing at 8 Ph. I'm assuming then that my soil is probably too alkaline. The plants are healthy looking but a bit slow growing. That's partly because the lights I have to use right now are a bit underpowered. They're full spectrum LED T5 type grow lights but the PPFD for them is only registering around 400 and I can't get them any closer to the canopy because it will be too hot. Is there anything I should do or can do to lower the Ph of the soil? I hesitate to start adjusting my water to 5, 4, etc since that would see too acidic to me and the plants are going to take up the water probably before a slow uptake through the watered soil. Or, do I just leave the grow as it is and keep doing what I'm doing?
They're at about 5 weeks from seed planted directly on the bags and I've been training with LST from early on.
Far, far too healthy to be growing in a mix with a pH of 8. I’ve found those cheap Rapidtest pH kits to be highly accurate - just need to let ‘em sit for a day before comparing to the color chart. If you planted autos directly into a super soil mix and not a starter mix, you are going to blow my mind. I find auto seedlings to hate a hot mix like that. RD
Almost forgot I use the exact same light except only half are LED and half are the old school T5 bulbs. I was able to get them awfully close without much issue. Worst that happened was the main cola foxtailed a bit. @Organic sinse has a great thread in the stickies for Autos. He can help you dial it in far far better than I.
Mind blown in 3..2...1. Correct. No starter mix. Germinated the seeds and then planted the sprouts directly in the super soil. Do you think they're tracking as they should be for 5 weeks? If I hadn't LST'd them then I'd guess they'd probably be not quite a foot tall now. The buds seem to be airy to me, but I'm still ignorant in these areas. I wondered if that was the lights being less than optimal.
The problem I have right now is keeping the temp at canopy level in check. If I put the lights any closer then the canopy temp would probably be over 85. Humidity is running between 75%-80%. Any lower on the Rh and the temp will go even higher. Fungus gnat problem from the very beginning that I'm keeping in check with sticky papers and every watering I'm using Bt granules. If I didn't there'd be a fungus gnat explosion. Next grow I think I'm going to add about 2" of washed sand to the top of every grow bag. I don't like using diatomaceous earth because it's a pain.
I see you left it to sit for 3 months or more. This was a wise and probably crucial decision. I’m curious what OS has to say on this. It’s kinda funny we talk about how new growers seem to do better with autos than experienced photo grower’s can do. RD
I would get some mulch down on the soil surface. This will help with gnats and bring down the RH more in line with what you want. (Less evaporation). Are you running your light 24/0. If not that would be the best way to add more ppfd. I wouldnt worry about airy buds at just 5 weeks. I actually think things look really good. If you want some cheap/free mulch ideas just holler. A downward look/pic at the plant soil surface would help. Cheers Os
Good on op for letting the soil sit and cycle that long. I can never pull that off. I wonder if it really mellows the soil out. Im also surprised they did so well being direct planted in super soil without some seed starter. Cheers Os
Back up your idea by using $5.00 pool strips from a local drugstore, many ph readers are crap made in china even for the expensive ones using a chemical strip will ease your mind good luck
I'm using a Ph liquid for testing. It's a yellow colored liquid. 3 drops in 50ml of water for the testing.
Thanks for the info. For lighting I'm doing 18 on and 6 off. Good idea to boost that up. I'm going to try that. Thanks to everyone who has offered comments or advice. It's reassuring me that things are hopefully on track. I watered early this morning and mixed the Bt granules with the water. I put out some new pest strips and checked them this evening and haven't seen any fungus gnats.
If you can cut out sheets of cardboard to cover the soil surface it will stop gnats, and bring down the RH. You just lift up the cardboard to water. In can be multiple pieces and doesn’t have to be pretty. Best easy free mulch solution. Cheers Os
fungus gnats.? lay un cooked french fries on the surface, check them in the morning remove the grubs, they are more active under a blue moon like recent, next one is in 2026 lol or get a yellow card smear cooking oil and hang above good luck