hi i have a big Problem with my plant is 3 weeks old now but it not look good

On the Leaves i have brown edges and after the new leaves come
out the biger leaves thay dry out , antil thay get dead

New leaves come withYellow leaf edges and thay later after new leaves come out thay dry out

my seeds sprot out from Rockwool Cubes and after a week i see
roods come out from the sade of the Rockwool Cube and
i put the Rockwool Cube in the soil

my p/h of soil is 7
my p/h of the water is- 6.5
the temperature is- 25 to 27 in the day
in the night -20
Time of the lamps- 24 after 1week 18/6

help me pls
thanks from be for
reuben Reviewed by reuben on . i need help 3 weeks old plant hi i have a big Problem with my plant is 3 weeks old now but it not look good On the Leaves i have brown edges and after the new leaves come out the biger leaves thay dry out , antil thay get dead New leaves come withYellow leaf edges and thay later after new leaves come out thay dry out my seeds sprot out from Rockwool Cubes and after a week i see roods come out from the sade of the Rockwool Cube and i put the Rockwool Cube in the soil Rating: 5