Increase pressure in hose line

We have a well on our property that pumps at a low of 37 psi to a high of 48 psi. The yield is 8 gpm. I have no problems currently with pressure and get lots of water out of my two 5/8" dia. hoses, each 100 feet long. I do want to run a line underground for about 85 feet from my rear sillcock to my shed where I will install another sillcock and another 100 foot hose to water my rear gardens and flowers. This means I will actually be pulling water to a point 185 feet from the sillcock on the rear of the house through two hoses.
I am in North Carolina and there is no problem with running underground lines using heavy duty Swan hoses just 6 inches below the surface as it is done around here all the time with no freezing problems.
My question is this: Should I reduce the diameter of the underground line to 1/2" or the new 100 ft hose to 1/2"...or both so my pressure will not drop?
Any help will be appreciated.

It doesn't work that way. Reducing the diameter of the pipe will reduce your pressure! The smaller the pipe, the higher the resistance to the flow of water, hence less water and less pressure at the other end. I would increase your pipe size to 1 inch to help reduce the pressure drop.

-rick

Thanks for the reply! I guess I was thinking that the reduced diameter would increase the pressure. I will look into getting 85 feet of 1" I.D. pvc tubing for my underground line and then 3/4" hose for the final 100 feet.