Growing a selection - 2 of 7 struggling with lower leaves browning. Help please!

Hello everyone!

My first ever post after being a lurker for a few years now, felt too much of a beginner to post before but I feel ready now with a little more expericence under the belt. Oh and I could really do with some help from some more knowledgable growers.

I've finished 4 grows now and altough I've had some smokable bud, things haven't ever turned out quite how I'd liked (I'm still learning). I'm determined this grow to get it right.

I've got 7 different plants growing at the moment and all are looking healthy so far, except for two plants.
Both have discoloured on their lower leaves, turning a grey-brown colour. I've looked around extensively and think it's a magnesium deficiency? I've been giving them plenty of feeding, so I'm concerened it may be over-feeding and locking out magnesium.

I've listed some info below and will post pics up too, if anyone has any opinions it would be greatly welcomed

Growing Medium: Plant Magic Soil+ with granules, currently in 1.5l pots
Seed Genetics: Royal Queen Seeds: White Widow & DNA Genetics: Chocolope
Plant Age: Plants are around 3 weeks old in photos since sprouting
Lights: Indoor under a 600W MH cooled hood light around 55cm (21") away from tips of plants
Feed Schedule: Watering with tap water (PH ~8.0) mixed with Plant Magic: Old Timer nutrients when first few inches of soil are dry and pots feel lighter. I'm also giving a light foliar spray of plain water once every few days.
Nutrients: Plant Magic Old Timer - Grow, Catalyst, Bio Silicon, Root Stimulant at a little over half the recommended dosage. Last fed 27th December
Temperature: 78F during the day, 64F at night. Humidity around 55%.

Humidity is occasionally dropping when the humidifier I'm using runs dry and I'm not around to refill.

Yep, Its a deficiency. Could be magnesium but probably calcium. More than likely a less than ideal pH range. Get it above 6 and make sure it stays there. I'd flush them and check the pH of your runoff, if its lower than 6 that will tell you if it was pH related problem. Also I'd get away from using tap water unless you got some good tap water... less than 150ppm. Get an air pump/stone and bubble your water for a day, or at least let it set for a day or two, to get all the chlorine out of it before you mix nutrients or even just watering. This will give you much more accurate pH readings when you first mix your nutrients. Also, just for a nice little treat for your ladies, add some magnesium sulfate (epsom salts) to you nut. solution for a nice bump in mag AND sulfur, they love sulfur.

Hey man

Nice to see a new, committed grower that actually uses proper grammar. Kind of a rarity around here haha.

Don't have much advice for ya, except to WAIT FOR MORE ADVICE. The above post seems like bad advice, since i'd guess your medium is to blame in some way. Adding more nutes/water is probably not the thing to do. I run hydro so i'm not certain what's goin on there exactly.

Also i'm pretty sure i see thrips on your leaf. Look those up.. Buy some neem oil and start spraying every few days.

Good luck!

SnaFuu said:

Hey man

Nice to see a new, committed grower that actually uses proper grammar. Kind of a rarity around here haha.

Don't have much advice for ya, except to WAIT FOR MORE ADVICE. The above post seems like bad advice, since i'd guess your medium is to blame in some way. Adding more nutes/water is probably not the thing to do. I run hydro so i'm not certain what's goin on there exactly.

Also i'm pretty sure i see thrips on your leaf. Look those up.. Buy some neem oil and start spraying every few days.

Good luck!

Click to expand...

I hope you would notice little bugs flying around and the little larva on the leaves if it was thrips. Its either a mag, cal or sulfur deficiency just showing up. Those leaves will continue to grow but they will get worse, to the point of turning almost completely brown and drying/shrivling up. But you spray all the neem oil you want on there and see how that helps... tell me I give bad advice.