Bottom leaves browning?

Grown in only coco and perlite? Are you using any fertilizer? Have you got a suitable light?

 

Never FEED YOUR SEEDLINGS UNTILL THEY HAVE 5 OR MORE TRUE SETS OF LEAVES.

When growing hydroponic marijuana the pH of the nutrient solution should be between 5.5 and 6.8. In most
cases optimal pH is about 5.8 to 6.3 but this may vary slightly depending on the particular marijuana
strain and the growing conditions you provide.

Some growers report good results with pH as low as 5.0. You can experiment to see what works best for
your particular plants but always keep the pH between 5.0 and 7.0.

Measure the pH right after you add the nutrient solution to the reservoir (mix well first) because the
nutrients will change the pH level of the water. Check the pH level about once a week.





"Adjusting pH of Hydroponic Setup"


pH-up and pH-down solutions are used to adjust the pH level of hydroponic nutrient solution and hydroponic
media when the pH is out of range. pH-up (also called pH increase) is used to raise the pH level and pH-down
(also called pH decrease) is used to reduce the pH level. A pH-up or pH-down solution for hydroponic or
aquarium use is recommended.

For hydroponic applications, nitric, phosphoric or citric acids (even vinegar) can be used to lower pH,
while potassium hydroxide can be used to raise pH. If you understand what you are doing, you can use them
instead of buying pH-up and pH-down solutions (contributed by james and jorge).

However, if you aren't sure of the correct amount of acid or base that is needed to adjust the pH to
optimum values, it is best to buy a solution specifically made to raise or lower the pH and carefully
follow the manufacturers instructions.

Unless directed to do so by the manufacturer, don't try to adjust your pH by more than 0.2 per day.
Make drastic changes over a number of days. If your pH is 7.0 and you would like it at 6.5, try
lowering it by 0.1 a day for 5 days (or do it even more gradually). Overcompensating can spell disaster
for your garden.

 

If your using a medium devoid of almost any nutrients like coco coir and perlite I'd start at 1/8 strength after the first few days.

 

You're not growing in soil - coco is drain to waste hydroponics - the pH should be around 6.0 not 7.0. Don't listen to the above poster, coco is inert and like all hydroponics, food should be available from the beginning. I would not wait until the 5th set of leaves like he suggested. I feed every day to run off from sprout and twice a day to run off when in flower - never plain water.

I'm no expert at diagnosing plant problems but it appears to be pH related.
Good luck.

May I suggest you educate yourself on the correct way to grow in coco? Go to www.cocoforcannabis.com for the straight scoop.

 

The problem with mixing soil and coco is that they both require a different pH for efficient nutrient uptake. You might consider using just coco and perlite when you transplant. A 70/30 coco/perlite mix is best.
Good luck.