Hi Yodio, I'm also a newbie gardener and I can't really answer your questions about how well they will grow, but I have a picture of the green wire fencing that I've attached to a trellis up against my garage that I thought you might be interested to see. This is my first year with clematis. My garage is a pale cream color, and the trellis with the wire fencing is not really as noticable as you'd think (not an eye sore), and like you, I was afraid it was going to stand out like a sore thumb but it really doesn't because the wire is so thin, and from a distance (I've viewed from my neighbors yard) you can hardly tell it's there. This is also a north facing wall, and I've planted the clematis behind my shrub and ferns. I've swapped the garbage can with the yard waste bin to allow more light to get back there, but they've grown well so far (I have minuet and alba luxurians - I've cut them down again to promote root growth, but they both made it 3/4 up the trellis already without direct sunlight). I still need to add a downspout extension so my clems don't get overwatered, but only time will tell if they will bloom in this area (no direct sunlight). If you look at the fenceline in the background, I also have clematis planted there (this pic is a couple of months old), and those get mostly indirect sunlight, but they will get direct sunlight once they grow to the top of the fenceline, and some of those have already produced blooms. I'll let the experts answer the questions regarding lighting and planting as they'll know better than I.

I have 5 ES + 1 PG growing inside of 12-15' radius from the trunk of the black walnut tree for 3 years and everything seems to be fine. To make matter even more complicated I also planted last year a very young climbing hydrangea seedling to grow on that trunk. However, I didn't dug even an inch deep in a soil. Tree was planted on a slight hill and I just gradualy added 4-6-8-10" of the soil to create depth for the planting and planted relatively small plants with root systems that could fit in those 6-8-10" depth. I have no clue what will happen next, will WT poison the hydrangeas eventualy or its roots will stay where they are, but so far everything look absolutely perfect.

I don't know a lot about Hydrangeas either, but a few things. The standard (mophead /lacecap or macrophyllas) hydrangeas you get in a pot bloom on old wood. With dry cold winters you need to protect that wood or it will die back and you will get a foliage but no blooms. That is what happened to me the past several years and the plants don't grow much since they just get back what was killed over the winter. To protect them I guess you could cover the plant with mulch in the late fall. Also, the standard potted hydrangea is an acid loving plant so they are iffy if you plant them in akaline soil. I love them so much I tried to ammend, but they have just kind of survived, not thrived. The color changes I understand are achieved with variations in the acid PH, but they still need acid not akaline soil to thrive (which we don't have). The other varieties like Oakleaf or PeeGee hydrangea fair better in dry (air) and akaline conditions. They also bloom on new wood which is nice because they are determined to bloom every year regardless of protection. I remember my Grandma had beautiful macrophyllas in her Cheyenne Wyoming yard. Either the soil is more acidic there, or she had a great secret.

You want to be very careful amending planting holes in a clay soil. Adding 'better' soil will just result in a bucket of very moist/wet soil with slow drainage. This can easily lead to root rots. You either want to amend the entire planting bed/area or just dig a very wide but shallow planting hole in the clay, site the plant high (slightly above grade) and back fill with ONLY the soil removed. Any amendments can be used over the existing soil as mulch and to mound up to the base of the rootball. And almost any kind of plant (excepting those that require very fast drainage) can be grown in a clay soil if you follow this method. The only hydrangeas I would consider planting in full sun are Hydrangea paniculata cultivars - all others need some afternoon shade.