Adding fert to soil mixture

Hi,

Ive got some Bahia Blackhead (KC Brains) germinating, and I'm using 50/50 compost and sharp sand mix as a potting medium (drains really well).

I always seem to get some defficiencies after 1-3 weeks of growth, starting with the bottom leaves going pale and then brown and crispy, and then the tips of the upper leaves go brown and crispy too and growth slows down alot.

Is it worth mixing some small amount of ChemPak no.2 (npk 25:15:15) into my soil mixture, as when I try and liquid fertilise I always end up buring them and everything gets worse.. (1-2spatulas per 5 litres)

I'm growing under 400W MH, but soon to have a 400W HPS alongside aswell.

any advice on diagnosing my inherent problem, and fertilising tips - most appreciated.

Have you ever done a soil pH test on your mix? I'm wondering if you may be too acidic. As for burning your plants with too-heavy fert, what are you using for a vegetative growth fert? As a starting adjustment, I'd suggest fert at half your usual strength.

Also are you puttings seedlings under your HID lamps? They might not be liking it. Are you seeing negative phototropism (leaves turning away from the light)? Also what are your temps? Seedlings can be really fragile under HIDS. You might try putting them under floro until they get established, then put them under HID. I'm mentioning this because you mentioned growth slowing down...It could just be nutes, but it could be alot of other things as well. Good luck.


Dboy

thnx, ill do a soil ph test and grow the seedlings up for a week under non-HID light,

Im using std tomatoe/veggie grow bag soil - mixed with sharp sand, maybe there is too much organic mater in the grow bag soil (it is pretty black)..?

Oow :)

I found bargain soil pH test meter(pH4-pH8) and soil water meter at B&Q £6.94, no bad. :)

Tomato soil should be fine. Very dark soil sounds good too. Let me know how your pH test comes out. If you decide to pH test your water as well, be sure to meter the runoff water as well as the water going in. In other words, get some of the water that comes out of the bottom of the pot as you water, and test that. Also feel free to post a few pix of the plants as they develop.

There are a lot of smart people on this site who would be happy to help you out. More info will get you very good answers. Good luck, and show your plants you love them:-)

Dboy

pH has come out to be 7, I wasnt expecting it to be outside of a neutral range, anything lower than 5 or higher than 10 you can feel with your fingers as a slimey residue (which is the proteins in your skin being denatured by the pH)..

All is looking good, I just have to be careful with the light intensity for the seedlings, and later very weak feeding.

derstig

brown crispy leaves means too much salt/fertilizer.
Too much fertilizer will also stunt the growth of your plant.

dai*ma :stoned:

Once i got a cigarette from this hippie that smelt kind of funny and it made me very hungry and thirsty too. wowie.

I would use 1/4 srength ferts on young plants, gradually build up

i always thought it was over fertilising, but iv been using tiny amounts, much less than stated on the box.. maybe just over watering aswell.. . . . this next crop should be alot better . .

Yeah it could be multiple issues. Good to experiment with the cheap seeds:-) I know it sucks "wasting" all that time, but you'll learn a ton. By the way, what size containers have you been using?

Dboy