Not sure why plants are growing very slowly

[kronicking]

Hi, I am growing some autoflowers and I was wondering if anybody might know why my plants seem to be growing very slowly. They popped their head above soil approx. 11 days ago. They are only on the 3rd set of leaves and are extremely tiny maybe 3.5 inches tall. I have 2 fastbuds 6 shooter growing 1 looks like it is better genetics as it is growing faster and bigger. 1 is some free cheese seed which is seriously small and not just started growing out its second set of leaves. I watered my plants and they all started drooping as if over watered. This was about 10 hours ago and they still are drooping but maybe a little less. The sunshine mix #4 was bone dry up too my whole pinky going in and there was some moisture under that not much but I am sure if i got farther it would be moist. I see lot of people saying to water till runoff about 20% but I maybe got 5% runoff (only watered that much this time usually water a circle around plant not getting entire soil wet an no runoff because it doesn't seem to dry) and my plants started drooping like crazy. The pot seems to dry up to the pinky in about 4-5 days (without getting runoff and only watering circle around plant) but the bottom soil doesn't seem to dry up using sunshine mix #4 with a ambient temperature usually around 77F, Soil temp approx 1/3 down is 70F low RH around 30% (can't raise humidity even with humidifier due to climate) using 5 gallon smart pots, powersun 630 watt CMH approx 32 inches from canopy moved up because leaves were cupping but maybe because of low RH I am not sure how close to have the powersun 630 watt CMH. I don't understand how you are supposed to water the whole 5 gallon pot and get 20% runoff with a small plant like people have been telling me without it drowning it.

 

[kronicking]

I thought I should add that in my last watering when I watered and got runoff I decided to check the ph and it was at 6.9 for the plants that were growing slowest and 6.5 for the ones that were a little faster and I decided to try and pour some 5.5 ph to get it lower I am not sure if that would cause these affects. Also the ppm of the runoff was 700-900 on all the plants.

 

[Listersmeghead]

I thought I should add that in my last watering when I watered and got runoff I decided to check the ph and it was at 6.9 for the plants that were growing slowest and 6.5 for the ones that were a little faster and I decided to try and pour some 5.5 ph to get it lower I am not sure if that would cause these affects. Also the ppm of the runoff was 700-900 on all the plants.

Hi kronicking,
The 5 gallon pots are quite large for small plants, when growing autos it's recomended to go straight to large pots,but it's still a little much to water the whole pot when the plant is little.
In the first 3-4 weeks it's best to water to the radius of the leaves around the plant,leaving the outer portion of the pot/soil dry.
At the moment you may be over watering them,the top of the soil may be dry but may be still to damp underneath to promote good root growth.
My autos only get 2 w aterings in the first 3 weeks.
Have a search on this site for "watering autos" some great info on here.
That light is very powerfull for a young plant, distance is not a bad thing until they're bigger. Your light may be drying out the top of the soil making you believe that need more water.

 

[Listersmeghead]

Oh by the way 3rd set of leaves day 11 is quite normal,autos start slow for the first 3 weeks then explode.So sounds like you're doing ok, just watch the over watering.

 

[kronicking]

Awesome! Thank you very much for the reply. Good to hear this is a normal rate of growth. I was starting to wonder because I was looking at a couple journals of this strain and a few seemed like they were bigger but I am sure they are using coco or something and are way more experienced. Also the journals aren't very clear on what day 1 is if that is when it popped its head out or if that is the start of germination from seed. I had a feeling I was overwatering the whole time but I keep reading online people saying to give the pot a good presoak and water every 4-5 days etc. I will try to water less next time around and give them a good drying this time. I am curious if anyone knows of good distances at different stages of growth for the powersun 630 watt CMH? Or if there is a way by looking at the plants to see if they are in a good light range. I can't seem to find any info online about these lights.

 

[Listersmeghead]

A 600w cmh is a very powerfull light, I use that (hps) for full flowering. For starting seeds indoors i personally use t5 lights 120w worth, this is good for the first 3 weeks. So you can see how powerful your light is.
You've moved them up to a good height already, correctly, so you seem to have the good intuition. Keep an eye on them, you might have to back it off a little more.
By the sounds of it, you've got it under control, just need some confidence on the watering, don't worry about ph of run off, if the correct ph going in, all good.
Have a search for watering autos, put your mind at rest.

 

[kronicking]

Maybe I should consider removing a 315 watt bulb to lower the wattage. Might help a bit I believe but maybe next grow as I don't want to stress out the plants. I will also maybe look at getting a more suitable veg light and just using the CMH as a flower light. I read it might be powerful but it was all I had atm and I was antsy to start my first grow so I thought I will go for it and see what happens. Also next watering I will give them the correct ph and hopefully they will be happier. Thank you very much for the info, you really put my mind at ease.

 

[Listersmeghead]

No worries
Yeah, the 315 would of been better to start you off. Like you say I don't know if it would stress the plant if you took the bulb out now,but just keep it at a good distance, that may have been drying out your top soil quicker. Sometimes to much light can make the plant droop.

 

[kronicking]

Thanks everyone for you opinion. It seems to be helping keeping the light at a better distance. I am stilll having a problem I believe with watering though because I am not too sure about what I am reading. I see people to say let the top 2-3 inches dry before watering but my mix is still moist at the bottom (sunshine mix #4) and is staying moist even in the smart pots and low humidity (30%). So I was thinking about mixing sunshine mix 4 with approx 30% perlite next grow but I am having a problem with some of the info I am reading. They say not to let any capillaries dry out because they will die and I am allowing a large chunk on the top of the mix dry because it is maintaining moisture even after i think 10 days and seems like the pot won't completely dry top to bottom for 3 weeks. I do have a heating mat under it so it is not getting air from the bottom but need the mat or soil temperature drops to 66.2F So I was wondering if it a good idea to try and water a little bit every once in a while just to make sure the top doesn't dry out too much causing a root to die?

 

[Nunyabiz]

Sounds like you need some more aeration in the soil, like 30% or so.
About 25% pumice and 5% biochar is good.
And water the plant not the pot.

 

[kronicking]

Thanks for the info. I had a feeling I watered way to much at the beginning because I saw tons of people saying to water the pot till runoff which seems like a big mistake (i think the wetting agent in the sunshine mix #4 is not helping). Next time I am going to water a lot less and around the seed/seedling instead of the whole pot and more often although I read the purpose of watering the whole pot was so that the roots will search for water and create a bigger root ball. I assume just making sure to water a bigger and bigger circle slowly is probably the solution. I am curious what the advatage to using pumice and biochar compares to perlite?

 

[Grassmaster]

If it's too cold the plants will go dormant. Needs to be ideally 78 degrees F. 315 's are great for vegging plants in the winter. But 2 lights may be a bit much. Take one of the bulbs out if possible until the plants are older.

 

[kronicking]

thanks for the info. I was thinking about taking 1 of the lights out but it is an autoflower on about 16 days so I am not too sure if it is too late for that? The temperature is not cold at all in the tent and actually I seem to be having a problem keeping it at my desirable temperature which would be 77F. The tent seems to go up to about 82.4F if I leave it all night without opening it even if I set my fan to keep it cooler. The root temperature stay around 74.3F but have had them drop because I took out the heat mats to see if I could get the temp good without them (heat mats aren't on by the way I guess the black color is creating heat from the lights) but without them on the bottom the temperature drops to 66.2F.