Why are my seedlings growing so slow?

Hey dudes what's good this is my 3rd grow but this is my first time grow with a 600w led light I'm on day 19 my seedlings haven't grown like expected? In comparison to other growers on day 19? I'm behind in terms of growth?!

My temps are usually between 16c -23c
Humidity about %61

It's very cool most the time also the stems have turned purple on the seedlings my led light has been kept on 25% seeing as they are seedlings However I'm starting to think is this the reason why they are growing so slow?? Could it be time to switch up the led to 50%? ...

Day 19

I can't help with the light question but the cold temperature will definitely slow growth.
You might consider starting in smaller pots next time.......I start in solo cups.

MickFoster said:

I can't help with the light question but the cold temperature will definitely slow growth.
You might consider starting in smaller pots next time.......I start in solo cups.

Click to expand...

Ok cool thanks so start them in smaller pots until? ..... Then I plant them in bigger pots

Looks like you’re growing in coco?

16-23c is chilly, especially for LED. 20-27c would be better

Lack of light would be stretched stems

itsaliveterps said:

Hey dudes what's good this is my 3rd grow but this is my first time grow with a 600w led light I'm on day 19 my seedlings haven't grown like expected? In comparison to other growers on day 19? I'm behind in terms of growth?!

My temps are usually between 16c -23c
Humidity about %61

Click to expand...

The more info you provide, the easier it is to troubleshoot.

Per @MickFoster, the temps for your grow are fairly low. 27° to 30°C will increase growth.

Also, the combination of temperature and RH (and wind speed/fans) are the factors that drive how much water a plant gives off. The temp + RH can be combined into one number referred to as "VPD" or vapor pressure deficit. The key point is that, when it's cool and moist, there's less transpiration from plants. Per the graphic, the VPD for your grow is 0.8. That's good for very young plants but it's lower than ideal for a 19 day old plant. It's not "way out of whack" but it is about 25% low and that means that the grow isn't getting as much water, and therefore nutrients, as it should. This isn't a major issue, but raising the temperature and/or lowering RH will help.

itsaliveterps said:

It's very cool most the time also the stems have turned purple on the seedlings my led light has been kept on 25% seeing as they are seedlings However I'm starting to think is this the reason why they are growing so slow?? Could it be time to switch up the led to 50%? ...

Click to expand...

Perhaps.
What make and model light are you using and how far above the canopy is the light ("hang height")?

More information about the grow would be very helpful including pictures of the plants and the grow tent, temperature, RH, wind speed (fans), nutrients, nutrient schedule, grow medium, etc. etc.

Nutty sKunK said:

Looks like you’re growing in coco?

16-23c is chilly, especially for LED. 20-27c would be better

Lack of light would be stretched stems

Click to expand...

Yes I'm growing in coco? What are you implying?

Yes I would agree 16c -23c is chilly especially with my intake on? And extraction on? At the very minimum.. wondering if it should even be on? Lol

Best I can do is switch on the heating for an hour or so but it's been quite chilly here

Delps8 said:

The more info you provide, the easier it is to troubleshoot.

Per @MickFoster, the temps for your grow are fairly low. 27° to 30°C will increase growth.

Also, the combination of temperature and RH (and wind speed/fans) are the factors that drive how much water a plant gives off. The temp + RH can be combined into one number referred to as "VPD" or vapor pressure deficit. The key point is that, when it's cool and moist, there's less transpiration from plants. Per the graphic, the VPD for your grow is 0.8. That's good for very young plants but it's lower than ideal for a 19 day old plant. It's not "way out of whack" but it is about 25% low and that means that the grow isn't getting as much water, and therefore nutrients, as it should. This isn't a major issue, but raising the temperature and/or lowering RH will help.


View attachment 5459217



Perhaps.
What make and model light are you using and how far above the canopy is the light ("hang height")?

More information about the grow would be very helpful including pictures of the plants and the grow tent, temperature, RH, wind speed (fans), nutrients, nutrient schedule, grow medium, etc. etc.

Click to expand...

Alright I'm using a 600w omega infinity led light

light hanging distance is about. 14-16 inch

Rh is about 61%

Currently no circulation fan however using intake fan with a speed controller which is set at the very minimum & I'm also using a digital spyder controller extractor fan which is set on level 1 (minimum) basically because it's chilly

I'm still in the process of learning how things work it's my 3rd grow also known as trial an error lol so take it easy on me haha

itsaliveterps said:

Ok cool thanks so start them in smaller pots until? ..... Then I plant them in bigger pots

Click to expand...

I transplant from the solo cups to 2 gallon pots at 2 weeks from sprout.
Don't go by time though......go by size.
15 days from sprout......... the day after transplant.

The way I see it, you need to get the temps up.

The options are,

a heater.

Or

Running fan on 1minute every 5, you'd have to experiment to see what works best as far as timing.

Or

turning the light up but raising it far away, so your increasing wattage without increasing intensity.

MickFoster said:

I transplant from the solo cups to 2 gallon pots at 2 weeks from sprout.
Don't go by time though......go by size.
15 days from sprout the day after transplant.
View attachment 5459235

Click to expand...

Wow thats a picture of just 2 weeks I thought seeing roots poking out the bottom of a small pot would be an indication to transfer thanks for the advice

itsaliveterps said:

Alright I'm using a 600w omega infinity led light

light hanging distance is about. 14-16 inch

Rh is about 61%

Currently no circulation fan however using intake fan with a speed controller which is set at the very minimum & I'm also using a digital spyder controller extractor fan which is set on level 1 (minimum) basically because it's chilly

Click to expand...

The manufacturer of your light doesn't provide a crucial piece of information about your light called the "PPFD map" so I can't give a solid answer on light. A good source of info is the manufacturer so you might want to check their website.

Based on the values for the FC 4800 here, it looks like your light is a few inches high.

coreywebster said:

The way I see it, you need to get the temps up.

The options are,

a heater.

Or

Running fan on 1minute every 5, you'd have to experiment to see what works best as far as timing.

Or

turning the light up but raising it far away, so your increasing wattage without increasing intensity.

Click to expand...

So yesterday I increased the led light intensity from 25% to 50% seems to be working I think lol

Also not sure wat u mean on how to run a intake fan? every 1minute every 5minute? I think u mean right :/? Lol

Delps8 said:

The manufacturer of your light doesn't provide a crucial piece of information about your light called the "PPFD map" so I can't give a solid answer on light. A good source of info is the manufacturer so you might want to check their website.

Based on the values for the FC 4800 here, it looks like your light is a few inches high.

Click to expand...

Oh no so I should lower it a few inches downwards :/?

itsaliveterps said:

I'm still in the process of learning how things work it's my 3rd grow also known as trial an error lol so take it easy on me haha

Click to expand...

No! Beatings will continue until moral improves!
Hehe we were all new at one point. Best thing you did was show up here. Lots of help available.
Something that might help you is reading some grow journals that map out a method of success. Find a grower who is using your style of growing like coco, soil, airpots or whatever and follow the grow. Look at options for seedlings as this is not cut and dried there are lots of methods. Some use cups and some place directly in final pots. Heck we do not even agree on how to germinate a seed but this proves there are many paths to growing success.
Finally there are many ways to grow pot but even with all the ways there are still rules you will need to follow in your enviroment to grow GOOD pot. Here are some lanes
You will need to control your temp from 30c to 21c over the life of the grow.
You will need to control your humidity from 75% to 40% through the grow and when you need the lowest humidity is when your plants will be producing the most transperation.
You will need to test light strength and modify this through the entire grow or learn very quickly how to read plants for light
You will need tools to properly dose nutrients. These tools measure PH and EC-ppm and do not cost 29.95 for both tools in a nice green box. They cost a hundred bucks each when you buy them with the chemicals to maintain the tools. This is not an option. Those cheap tools will flat out ruin your day.
You will need a method to ventilate your grow area through the grow.

If you are unable to do any of the above you can still grow pot but you will not enjoy the end results. You will be frustrated ( I was ) and have to repurchase things you already have that do not work. I have 500$ in hydro parts that are now a waste and use organics as it matches my experience growing food.

Delps8 said:

The manufacturer of your light doesn't provide a crucial piece of information about your light called the "PPFD map" so I can't give a solid answer on light. A good source of info is the manufacturer so you might want to check their website.

Based on the values for the FC 4800 here, it looks like your light is a few inches high.

Click to expand...

I think it 1890 ppf

itsaliveterps said:

So yesterday I increased the led light intensity from 25% to 50% seems to be working I think lol

Also not sure wat u mean on how to run a intake fan? every 1minute every 5minute? I think u mean right :/? Lol

Click to expand...

Personally I wouldn't want more light intensity, but I'd want the heat that comes with turning it up.
Least at the size they're at.

And yeah, that's what I mean with regard to timing, but you'd need smart timer to do it.

itsaliveterps said:

Yes I'm growing in coco? What are you implying?

Yes I would agree 16c -23c is chilly especially with my intake on? And extraction on? At the very minimum.. wondering if it should even be on? Lol

Best I can do is switch on the heating for an hour or so but it's been quite chilly here

Click to expand...

You don’t need to start in a final container that size. Pot up. Each watering brings fresh oxygen/nutes and a growth spurt.

When they are that young they don’t even need extraction. Simply opening the tent once or twice a day is enough