I have a well, when the water is not running the pump pressure is at 55psi but when I run the water to water the garden out side the pressure drops to 20 psi and hardly any water comes out the hose ( there are no kinks in the hose and no filters atached to the out side water suply

Check the air valve on top of the bladder tank. If air comes out turn the pump off and open a cold water valve to bleed off the pressure. Now recharge the tank to 2PSI UNDER the cut in point on the control box, If water squirts out of the air valve replace the tank, Good luck, Tom