None of the common rose fungicides is truly systemic. A true systemic is transported both upward in the xylem and downward in the phloem. The tebuconazole fungicide in your Bayer Advanced product is upwardly systemic in the xylem only. It cannot travel backward and downward from the leaves on a sprayed stem which means it can't then move upward to a higher stem and enter its leaves. What it amounts to is, if you don't spray a leaf, that leaf isn't protected. The safest and the most effective way to spray a climber is probably with a ladder. Standing below falling spray isn't a good idea.

"Right" pH is a bit of a misnomer -- most plants will tolerate, even thrive, in a relatively wide range of pH and peppers are no exception. A quick Google search turned up the following ranges: 5.5-7.0, 6.0-6.5, 6.5-7.5. Unless you were growing a specifically acid-loving plant (blueberries, potatoes, etc.), a slightly acidic soil (6.3-6.8) is the preferred range for the largest number of plants. I wouldn't bother to do any adjusting to a potting soil. The need for frequent supplemental fertilization for any containerized plant will override any need for fine tuning the pH any further.

Also, keep in mind that even most breathable landscape weed barriers get their pores clogged over a very short time. Because the blocked breathable pores cause conditions that weaken and kill living plants, It is not a good idea to use those products. In my opinion, a better approach would be for you to remove all the weed barrier and in it's place put down 4 or more layers of flattened cardboard (not the corregated type that consits of too much glue, instead use the thiner cardbord type found in shoe boxes and other packaged products. Maybe even poster board often used for science project displays.) Cover the cardboard with 6 to 12 inches depth of good garden soil where ever you plant each groundcover start. Then cover the entire area with a good acidic shreaded mulch at least 4 inches deep. Over time keep filling in the voids with more garden soil around the original groundcover start's soil as they seek to send out runners or roots to spread into a dense coverage. Once the groundcover gets established and is healthy, it should competively crowd out all but the most tenatious weeds. As the mulch settles it should be replenished to aways maintain a 4 inch depth. It is also my opinion, that just like the best way to fight weeds in a lawn is to keep the desired grass as full and healthy as possible, the same is true for desired groundcovers.

Bearded iris not Louisiana iris. That one needs too much water. Your growing situation and soil in Seattle have nothing in common with what I am dealing with. Collecting water in an semi arid area on top of a limestone hill is very different from what it means in a place of cool mist. Water is transitory even in the wettest places here during the wettest times. I can have 16" of rain in 24 hours and no puddle in this area. It will retain some moisture longer, which is a good thing here, but it will then get dry.. It gets moisture easier during little rains which is a plus. Please don't take this personally. I will have to even take responses from the big state of Texas with a note of where the responder is coming from. Gardening in Houston and Dallas, and South Texas is very different from me. But at least we have heat in common and in most places, alkalinity. They never grew well in one area probably due to shade but this area had deeper richer soil naturally due to the oak tree above. The only place that they grew well was by my grey water outlet which got lots of water. It is too shady for them there now. I need to make a new spot.