New grower problems

[potbelly]

Hello everyone...

 

I have just started to grow from seed. Germinated and planted fine and for first 3-4 days all looked good.

 

Now the leaves are starting to yellow. Not sure how to describe it, but they seem less green than before and they are starting to yellow. One of them (in blue pot) shows noticeable burn marks.

 

They have been growing for about a week. Ph is 6.0 and I am growing in COCO with bit of perlite thrown in.

 

I am using Canna COCO A&B mixed at rate of 1.25ml/L for the moment. I water once a day until I get about 30% run off (which doesn't take much) The lighting is HPS 400w which is about 50cm away from the plants. Grow tent is 1.2x1.2x2m and temp in there ranges from 28deg to 33deg on hot days. I run 18hr on, 6 hr off. Water is left around for couple of days before using.

 

Any help would be greatly appreciated.

[Home_Grown]

Firstly, back off the nutes and give plain water for a couple of days.

 

Secondly, raise the light, 50cm is too close for such young plants. I'd say maybe 90cm would be good if you have the height to play with.

 

Thirdly, How often are you watering? Yellowing leaves can indicate either too much nutrients or watering too much.

 

I let my pots fully dry out before watering.

[ijustdontcare]

go with what home_grown said hit the nail on the head..

[potbelly]

I water every day. Enough to saturate the pot completely. I read somewhere that you can't over water in coco and that it is better to water more often. I'll back off and see what happens.

 

I have about 1m to play with, so I'll move the lights immediately.

 

Thanks for the quick reply!

[Home_Grown]

I water every day. Enough to saturate the pot completely. I read somewhere that you can't over water in coco and that it is better to water more often. I'll back off and see what happens.

 

I have about 1m to play with, so I'll move the lights immediately.

 

Thanks for the quick reply!

 

 

Well now you know that you can over water with coco/perlite. Watering every day to the point of saturation with young seedlings will drown them.

 

Water every 2nd or 3rd day - use your judgement, stick your finger down in the pots and if it feels nice and moist don't water or buy a moisture metre.

 

In my tent, i had a 600w HPS and I had my light way over a metre away from my seedlings, I gradually lower it down as they get bigger and to avoid stretching.

 

Keep us updated, they should bounce back in no time ;-)

[SukonmiSkunk]

leaves yellowing is in no way related to TOO much nutrient... its a sure sign of not enough nutrient..

 

theres a few things that inhibit the plants nutrient uptake.. just not enough.. PH causing nutrient lock out.. or salt build up in the soil...

as these plants are so small.. id be ruling out salt build up in the soil..

 

How are you measuring the PH... also how long does it take for the soil to dry out?

 

if youve got a PPM tester and a Ph tester.. what you need to do.. is measure just plain water with both.. and pour through.. collect all the run off in a bucket or something.. and test it again.. this will give you an accurate measurement on what the plants are receiving... this will effectively give the plants a flush too.. which needs to be done every 3-5 waterings..

 

if your PH is with in a range of 5.8-6.5.. then you can rule that out.. then the only other thing that it could be.. is NOT enough nutrient... which i think is the case...

 

these plants would be well old enough to be getting between half and full strength nutrient solution.. id say somewhere around 1200PPM...

 

also.. if your nutrient is left for a few days before watering.. then you need to aerate it.. or at least test it again before you use it.. you can get a cheap aerator from an aquarium place for around 20$..

[Home_Grown]

leaves yellowing is in no way related to TOO much nutrient... its a sure sign of not enough nutrient..

 

theres a few things that inhibit the plants nutrient uptake.. just not enough.. PH causing nutrient lock out.. or salt build up in the soil...

as these plants are so small.. id be ruling out salt build up in the soil..

 

How are you measuring the PH... also how long does it take for the soil to dry out?

 

if youve got a PPM tester and a Ph tester.. what you need to do.. is measure just plain water with both.. and pour through.. collect all the run off in a bucket or something.. and test it again.. this will give you an accurate measurement on what the plants are receiving... this will effectively give the plants a flush too.. which needs to be done every 3-5 waterings..

 

if your PH is with in a range of 5.8-6.5.. then you can rule that out.. then the only other thing that it could be.. is NOT enough nutrient... which i think is the case...

 

these plants would be well old enough to be getting between half and full strength nutrient solution.. id say somewhere around 1200PPM...

 

also.. if your nutrient is left for a few days before watering.. then you need to aerate it.. or at least test it again before you use it.. you can get a cheap aerator from an aquarium place for around 20$..

 

What SukonmiSkunk says is certainly true and you should rule out each point.

 

However, I believe that your problems are from over watering, not lack of nutrients as you are on almost full strength nutrients. Lock out could be an issue but I doubt it - coco and perlite is a pretty good buffer and if your between 5.2 and 6.2 pH you should be fine (http://www.canna.com.au/dhtml/products_coco_ab.php?lang=enx)

 

peace

[potbelly]

I use a digital PH meter (one from dick smiths). Dont have a EC meter.

 

I don't really let it dry out. I water every day so Im sure it's pretty much always moist. The plants are only about a week old. I am not sure if using full strength Coc A&B solution is a good idea.

[Home_Grown]

I also don't think full strength nutrients is a good idea at only 1 week old.

 

Half the strength and cut back on watering, betchya that fixes it.

 

Make sure your pH pen is calibrated correctly and as SS suggested it might also be wise to invest in an EC meter aswell.

 

Hope all goes well.

[SukonmiSkunk]

its why i asked how long the pots take to dry out..

 

if the pots are constantly sitting in water.. then what that does is starves the roots of oxygen.. i should have mentioned this aswell.. lack of oxygen inhibits root growth and the ability for them to take up nutrient.. also fucks with the PH.. so then you will get a combination of issues.. starting with over watering.. so yeah HG is right on it..

but its not down to too much nutes.. its because the plant cant take up nutrients.. they go yellow like this..

 

too much nutrient the leaves will still be green.. but the tips of the fingers will be brown/necrotic.. burnt..

 

so yeah.. cut back on the amount of water youre giving it.. it might also pay to get some cannazime.. it stimulates root growth..

 

also get a PPM tester.. as testing the run off is the only way to see whats going on in the pot...