here in montana our beds 2x12s 3 beds are 4ft x8ft and 1is 3ft x 27ft all with hoops. the 4 hoops are spaced equally on the 8 ft beds and the same on long about 2.5 ft apart. we use 3/4 in. sch 40 pvc with 3/4in crosses on the tops and and 1/2 up the sides I find about 27 in tall is about right. I slide 1/2 pvc through the crosses and dead end in 3/4 tees . now I cover with 6 mil clear plastic tried 4 mil but won't last long in the wind. I use clips on the plastic down. after the plastic is on use 1x2 strips to anchor the plastic to the 2x12s screw them down for easy removal . the hoops are pushed all the way to bottom on the inside of the bed and anchored. this way you have a place to anchor the plastic sheeting with the 1x2s to the top of 2x12s. be careful don't try to cut the hoops when in place they become springy and mabe loose some teeth.make the 1st one mark for tees and crosses remove and use as a pattern for the others. we use drip watering systems now. on some of the houses later when it gets hot here we remove the plastic and replace with a fine mesh like bridal veil cloth that we get at walmart that is 300 mi away. sure keeps the butterflies and others out. our soil here is heavy clay so I mix sand ,mulch and potting soil.