Hi there eflana. I answered on your other post... did you get it? Here it is... http://forums2.gardenweb.com/discussions/4552902/irrigation-vs-clay-soil?n=2

Did you get a chance to talk to the master gardeners in MI?

Hi, we do irrigation for a living. Our favorite drip system is drip line tube. The pipe that we use has emitters are spaced 1 ft apart and are pressure compensated, have backflow protection and are non clogging. The tubing is 1/2" and brown in color. The original manufacture was Netafim, an Israeli company, but the pipe that we are now using is sold by Rainbird . To protect against freezing and for line flushing, we install ball valves at the point in the drip lines that is a far a possible from the input source. We install a Netafim filter on the water source if we are using well water.

Eflana, check out this site: http://www.irrigationtutorials.com/

Freeze damage is an issue, but has nothing to do with clay.

Potential clogging is an issue, but has nothing to do with clay.

Where the clay is an issue is how fast you apply the water (gal/hour setting) and how close you apply the water.

An issue I don't think I've seen addresses anywhere, is that if growing HTs in a cold climate involves a LOT of replacing roses. Which means a lot of digging that can potentially damage irrigation tubing. So people who take these things seriously around here tend to end up with a fair amount of PVC piping. It is shovel proof, and can be fairly easily lifted in the fall to drain out.

The less free draining is the soil, the slower water must be applied, further from the plant, with fewer emitters and more volume per session but less often. The reverse is true for sandy soils. Hope this helps.