A few years back we collected Columbine seeds in a zip lock bag and tossed them about the backyard Philadelphia rowhouse garden, the crevices of the concrete alleyway and about the local urban landscape.
Having observed Columbine for sometime we have noticed that it likes to grow in rocky areas. Out of cracks. In Marianna Florida, we saw it growing out of a limestone outcrop, signaling its affinity with alkaline environments. Its spindly stems and compact leaves suggests a degree of drought tolerance as well. All of these things indicate that Aquilegia canadensis is well suited for urban environments.
This is perfect for our situation where we are trying to create a hummingbird friendly environment that is not dependent on feeders. The plants are now growing and thriving in the alley and have adapted well to the concrete crevasses and nooks. The Columbine also provides beauty to the landscape. Complementing the Hummingbird friendly Columbine in our block is the Coral honeysuckle Lonicera sempervirens (major wheeler) and the straight species Campsis radicans, the trumpet vine.
Lastly, it is notable how majestically the red flowers contrast with the grey concrete blocks of West Philly!
There was some decent variation of the species on site, here is a pink variety. We also saw some pale  blue specimens.
Here you can see the Lesser Celandine taking over. If local residents and volunteers could adopt a small, doable section and hand pulled these, maybe it could help mitigate the problem.
Here is a pale blue variety! 
