brown spots on leaves

this is my first grow and from wot iv read its a nutrient disorder causing the brown spots, my seedlings are about 2 weeks old and ive just started using a half strength nutrient sulution. so yer... just wanted to kno if i should increase or decrease the nutrients.

thats a caicium def .r u controling the ph u can get this with a high ph which locks out some trace elements post and let me no .how bad is it .....................

If you are growing in soil, your soil (depending on which soil you use) should have enough nutes in it for the first 4-6 wks, so you are quite possibly feeding too early, which has caused nute lock-out.
Have the cotyledon leaves(small round leaves) gone brown and dried up??That is a good sign its time to start with a mild nute solution..If the Cotyledons still look green and healthy,flush the pot with PH'd water,then just use water for a wk or two..
You can probably aim to start feeding a diluted nute solution when your plants are around the 4th or 5th node, or as soon as the Coty's die off.
1/2 strength nutes on 2wk old seedlings is a lil excessive to start off...Some strains dont like high nute levels,esp if there is still a bunch of nutes let in your soil...Try 1/6 or 1/4 of the recommended dosage for a wk or 2 then slowly ramp it up to around 1/2 to 3/4 dose.

If you have a PH meter, check the PH of the run-off water from the pots next time you water...Soil is usually a good buffer for PH, and as such doesnt tend to create too many PH problems, unless you are using Chemical nutes, like miracle grow or similar...Organic nutes barely affect my soil PH, and usually fluctuate around 6.5-6.8,
Organic nutes are also a lil more forgiving i you get over zealous with the nute regime...basically its a lil harder to over-nute with organics, unless you get really 'nute-happy'.

Are you misting the plants with a spray bottle?
That can create small brown burn marks all over your leaves if you mist while the lights are on, especially if youre growing under high power lighting...The droplets of water act like a magnifying glass and scorch the leaf membranes...

Pics would be good, for a better diagnosis...also what strain, growing medium , nutes etc.??

thanks alot for your reply and sorry about the lack of information. i am growing in a 50 - 50 perlite / vermiculite mix on a non return drip system. they are growing under a 1000 hps light, i am using DUTCH MASTER nutrients a 3 part mix for veg state and a 4 part mix for flowering..... i cant tell u much about it only wots on th label.... (a) 9 grams of hydroponic nutrient (b) 6 grams of calcium nitrate and (c) 3 grams of potassium nitrate in 10 lts of water for full strenght.

approx ppm = 1200 in pure water
1600 in tap water ( i am using rain water as i live in a remote area)

the cotyledon leaves are still green but are just starting to dis colour, 60% of my 8 plants are just starting to get 4th node. i test my ph on a daily basis and keep it around 6.5 (from memory)

so from what you have told me its pretty obvious i was pounding my plants with nutrients, so to get this straight wen my plants are on 4 - 5th node i should feed them a very mild nutrient solution n work my way up, and also flush my medium.

and if you dont mind i got another couple of ques...

iv noticed my per / verm mix holds a shit load of water and doesnt need watering for up to 2 days, does per / verm hold nutrients in it for that period of time or should i water them on more frequently

and also... when my seeds germinater i put them straight into mediums under 1000 watta and not under fluro's for a couple of weeks, is this a problem?

cheers, leigh ps: i am working on pics

if they are only 2 weeks old I wouldnt feed too much if at all. I waited 1 month to feed.

for germinating i use a floura fixture (they are like $10) because the 1000watt is gunna most likely be too harsh on such small plants. but if you keep it at a good distance then they should be okay. Just put it up quite a bit higher than when you would for a more mature plant. and then check the temp above the top of the plant and make sure its not too hot!

yeah cheers for that superhighme

Yeah i was experiancing similar problems with my young plants, from feeding too much to soon. i just went with PH'd water at 6.5 w/superthrive for a few waters and it seemed to get way better. now I am just giving them 1/4 strength nutes and will increase gradually. (Soil Foxfarm ocean)

Yer Thats Exacly Wot Im Gunna Do, Dont Think There Is To Much Else I Can Do. Thanks For Your Post, Cheers

wgld said:

and if you dont mind i got another couple of ques...

iv noticed my per / verm mix holds a shit load of water and doesnt need watering for up to 2 days, does per / verm hold nutrients in it for that period of time or should i water them on more frequently

and also... when my seeds germinater i put them straight into mediums under 1000 watta and not under fluro's for a couple of weeks, is this a problem?

cheers, leigh ps: i am working on pics

Click to expand...

With soiless mixtures, I believe it is ideal to water a couple times a day actually...if you have a drip system of course...otherwise watering everyday would be next best, however if you have them in big containers and it holds moisture well you can get away with watering every otherday or even every couple days...I do cause Im lazy. It shouldnt be a problem putting them under the 1000 watt right after they germ as long as you keep it very far away and dont let them get burned...

thanks for the advise guys, the more the better. im learning as i go.... the hard way by the looks of things