temperature accuracy?

hi. my plants only grow when the temp is warm i.e above 25 more like 30. the normal air temp is around 20-22 at the moment this cant be right . i have to artificially create heat to germinate and sprout seeds i do this by using a normal lightbulb which works well but drys the soil out and decreases humidity. i cant understand this problem and my plants dont seem to want to grow. im trying lowryder but ive tryed skywalker, white rhino snow white etc, etc.
the only plant ive had grow big i put sand in the soil . but it was a male.

anywhere in the 70's should be good, but you could have a strain that likes warmer temps than high 60's

try using a spiral floroescent instead of a normal lightbulb, way more efficient and i believe they run cooler.

what is your soil mixture