A few years I've left some canna tubers in the ground over the winter in zone 6 (typically varieties I wasn't very interested in saving). I think I got a good number to resprout and grow just one time (the bed was in an open location). It doesn't surprise me that people have success in a southern exposure up against the house or similar protected location in zone 6 (I've done well with Amorphophallus konjac and Nandina in such a spot). It'd also help to have exceptional drainage, and a covering of mulch would be a good idea too. I wouldn't depend on even this setting in the case of rare/expensive varieties though.

Just enjoying my morning coffee and it has finally stopped raining and the sun is out, here in Barrie. Some good morning reading here I find our Canadian Tire stores locally do not carry as much selection of plants as they used to They did use to have lots of those little potted perenial plants and then mark them down even 75% off But this year and last there are not really any interesting perenicals in the smaller pots I think you are quite correct about the plant department of Canadian Tire That mostly the staff taking care of it do not know much about plants and that having a garden centre for them is really not a money maker, at least not the plants but just something that all the stores have. Maybe in some stores there is better care, but I expect plants themselves are not that much of a money maker for Canadian Tire.

Joy, I planted my ES about 3 years ago. They were in 2 gallon pots when I bought them. I am in Zone 5 too and they seem to die back a bit every winter. Anyway, 2 years ago, they grew a bit and bloomed well. Last year, the plants exploded and grew like crazy! However, there were very few blooms (probably all got damaged by the late frost). This year, we had late frost and late snowstorm again. They killed off many tender leaves, but miraculously, the flower buds did well and now the plants are full of buds! In answer to your question, they did get big! The tallest one is about 4-5 foot tall now! So, they do get big, even in our climate. I guess you do need to be more patient... I did not apply much fertilizer except for Holly Tone last year. However, during the first couple of years, I really wanted to develop a strong root system so I watered them deeply almost every day. It did seem to help. Good luck!

Bobo has become my favorite hydrangeas for the last 2 years. I have 2 planted in a full sun location in the fall of 2013, as 2 quarts (~ 1 ft tall) small plants ordered online since local stores did not carry them yet. Both gave nice and long blooms in 2014, and have been doing great ever since. The size is much more compact (~ 3'x3') so this is a big plus for my small chicago area lot. In spring time, I only sprinkle a little bit (1 tbs per palnt) of Miracle-Gro® Shake 'N Feed® All Purpose Continuous Release Plant Food. There are several kinds, I use the one with NPK 10-10-10. I don't typically use fertilizer but rely mostly on mulching well. I agree with NHBabs that these H. paniculatas need to have more sun for best performance. Mine is planted in the same full sun bed with cone flowers, Phlox and black eye Susan. I almost never water them so Bobo endures the summer heat and drought just as well as cone flowers, etc. I did notice that my neighbor's little Lime blooms much less as they are in a partial shade locations than my limelights (full sun). I understand the fun sun in zone 5 (chicago) may be different from other areas.