My plants have tip burn how do I fix it?

If you do not have a flushing/leaching solution you can use ph balanced water. You want to balance your ph for your soil/hydroponic growing medium (soil 6-6.5, Promix 6-6.5, rockwool 5-5.5 ect.). Leaching/flushing solutions help remove built up nutrients in the water.

Tip burn on a Coleus leaf