Soil too dry

My grow room is a metre square with 1x 400w hps light. The temperature is mid 30s. The soil dries out very quickly and turns to dust within a day. Is there anything I could do to stop this or do I just have to water more frequently?

cool your room m8
below 30
lift yer light also just till u get some shade from folage
check for moisture a couple of cms below surface/or weight of pot. could be just the loose on the top thats bone dry

when you water it add more water...

make sure u get about 20% run off and also the smaller the pot the faster it dryes out so in other words...get a bigger pot.also wind from your fan is going to contribute to transpiration aswell as heat.