Aurora is definitely a cold zone 5. there is no benefit of 'lake effect' to moderate the temps during the winter--nor any of the 'heat island' that the city of chicago generates. i would hesitate to try butterfly bush(buddleia) or lavender. flowering quince, mock orange, kerria, hardy roses, lilacs, bridal wreath spirea, weiglia
as well as peonies will all do well. need to be careful with rhodadendrons. iris bearded and siberian, rubeckia, coneflowers and milkweeds will be happy. so will daffs
and most hardier bulbs-- species tulips work well, but many of the others could be treated like annuals since they don't seem to keep coming back. some mums will come back every year, but many don't. many annuals will thrive if they like hot summers-- zinnia's, impatients, cosmos,
dahlia's, canna's, cornflowers, morning glories, canna's,
petunias, snapdragons etc.

shop for bedding plants to plant out in late may. but she should be able to plant seeds such as zinnia and cosmos about a week-10 days earlier.

diggerb

Thank you 'diggerb2'. I will definitely schedule my trip to help the kids later than I had thought. Aurora is definitely a cooler zone than I had thought. I definitely will have to re-jigger what I had in mind. A lot of your suggestions would not challenge the newbie gardener too much. I assume daylilies are the usual cast iron producer? Appreciate it so much.
Susz 52

Just seconding diggerb2. I live about half hour from Aurora.
Everything she told you is correct. The most dependable plants, here, as in Canada, are the native species --- " rudbeckia, coneflowers and milkweeds will be happy. so will daffs and most hardier bulbs-- species tulips work well"...
Yes, daylillies are like weeds around here. Consider relatively newer varieties as Stella D'Oro that bloom for most summer unlike the older, common varieties.
I'm partial to Monarda ('bee balm') that I have hundreds of square feet of. It works in partial shade, 100% hardy.
Penstemon, Phlox (garden phlox that blooms end of summer), Red Valerian, Campanula, Centranthus (I have a lot of that too), Coreopsis (for full sun), Astilbe (for shade),Achillea, Eupatorium (very large native), Digitalis (partial shade), Aquilegia (for spring), Shasta Daisies, and Heliopsis.
I live on a few acres and have about 5000 square feet of perennial beds (not counting shrubs, trees, berries, vege garden). Everything I listed, I grow. I don't do annuals so can't help.
Yes, I do a LOT of gardening.

dear retiredtraveler: I too am retired. Thanks for your suggestions. I did need the advice, my zone is quite a bit warmer than Aurora. I had thought it would be colder but did not appreciate how great the difference would be. On the shores of Lake Erie where I live is as far south as you can get in Canada. There are orchards and vineyards and other than real tender perennials I can grow just about anything rated zone 6 to 7. Thank you for your advice. It would be a shame to plant something that would not winter and my newbie kids would think they did something wrong and give up gardening at all. Susz