Last year I purchased three from the same online retailer: Asao, Ivan Olssen and Fujimusume. I might add that none looked particularly strong upon receipt. I planted each in it's own suspended deck box with trellis facing due east in good potting soil. I planted mazus in the bed to "cool" their feet. They are watered daily in the summer here in NM and receive 6-8 hours of sun. One box is shaded earlier than another as it is sequentially closer to the house. Fujimusume is planted with the least sun and Asao with the most. Asao grew and bloomed but I managed to kill the others. This spring I replaced the others, from the same company, and again was not especially impressed with my purchase. Both grew a few inches and then just died. Asao is now 7 ft tall and blooming rather well albeit the lower leaves have black edges. Should I try another retailer, I have one in mind? Should I try stronger varieties? I need a good light blue and near white. Do you think I'm overwatering? Not enough sun? Insufficient nutrients? Any thoughts would be most appreciated!
Young clematis...Are some tougher or is there a trick?
My one cent...I live one zone south of you. To be successful with clematis you do need to know what each variety 'requires' to thrive in your zone. I live on the prairie, no wind break, experienced a 50% success rate with in-ground plantings. Now 2 years into growing clematis in 10-20 gallon pots and experiencing an 85% success rate.
You might be overwatering. Clems like evenly moist soil, but not wet feet. I can now say with confidence that they are tolerant of drought conditions, as we've only had 3 inches of rain in 3 months. They are certainly not looking as good as usual, but not dying The size of their containers might also be a factor. Clems will grow large and deep root balls that need room to spread. I add compost to the hole that they are planted in and use compost in pots to grow out babies, although I think a good potting soil would suffice. HF Young is a vigorous grower that borders between light blue and lavender. John Huxtable has been a terrific white for me and seems the least bothered by drought conditions. Three mail order vendors that I have had much success with are Silver Star Vinery, Brushwood and Garden Crossing. They may cost more initially, but if replacement is not needed, the cost is leveled. One other quirk of clems to keep in mind is that they will lead you to believe they are dead, but they're just hiding for some unknown reason. I had one not show itself for years, then one day there it was. Hope I could help and good luck on your clem venture!