Gardening Proper spacing of holes in PVC pipe for automated watering

Group:There is some confusion regarding how far apart the holes should be in the 3/4" Schedule 200 PVC pipe that is used in automating the watering of soil-beds and Grow-Boxes. Perhaps an early book contributed to that confusion, but Dr. Mittleider's best and latest thinking on the subject follows:Pipes should be drilled with 3 holes every 4" for the entire length of the soil-bed or Grow-Box. The holes should be made with a #57 or #58 drill bit. These are very small - much smaller than a 1/16" bit - and are usually purchased at a hobby shop. Sometimes the Ace Hardware stores have them.If anyone knows of a source that is country-wide, please let us know.the three holes should be drilled at 45 degree angles. This means that for the 3 holes you will have a center hole and holes on both sides at 45 degree angles - thus covering 90 degrees, or 1/4 of the circumference of the pipe.Many pipes have been drilled over the years with smaller angles than this - even as low as 30 degrees.We believe that even distribution of the water to the root zones of plants on both sides of a soil-bed - and especially in a Grow-Box, which uses the light artificial soil mixture - is best accomplished with the 45 degree angle holes.The figuring of the angle is done very easily: On one end of a pipe mark points on opposite sides of the pipe right in the middle. Turn the pipe and bisect it again in the other direction. You then have 4 marks on the end of the pipe that each are 90 degrees from the next mark. Choose any two adjacent marks, then make a mark in the center between them. Those three marks are the starting points for lines to be drawn the length of the pipe to identify where holes are to be drilled.To make those lines cut a piece of 2" X 4" 6" long. Cut a square piece out of the center of one long side of the 6" 2 X 4 exactly the size of your 3/4" PVC pipe. Find a good pencil, then drill a hole the size of the pencil from the opposite side of the 2 X 4 into the center of the square. Place your PVC pipe on a level smooth surface; insert the pencil into the hole; place the 2 X 4 over your pipe; hold the pipe from moving, and draw the pencil & 2 X 4 along the length of the pipe so that the pencil makes a line exactly where one of the 3 marks are inscribed on the end of the pipe.Next, place a tape measure along the length of the pipe, next to the 3 lines, and make a line across the three lines at 4" intervals along the length of the pipe.Drill your holes where those lines intersect, which should be at 45 degree angles, every 4" along the length of the pipe.Jim Kennard