You can use diapers to maintain the humidity in soil. There are two methods first is simple as i saw on sandpaper and silly putty. Just put a diaper on the bottom of pot, very simple.
For the second method you will need to fill the diaper with water and get the hydro gel out.
Mix equal parts of potting soil with equal parts of hydro-gel, mix the two together until they are properly mixed.
When completely mixed you will have an airy, super absorbent, super growing potting soil. Pot your plants with your new soil and your plants could go twice as long between watering because of the super absorbent water crystals in the soil.
And don’t worry the hydro gel is non toxic, biodegradable and environmentally friendly!
Awesome tips.