Thank you for your question.

Since there are multiple varieties of giant allium (Allium giganteum), we are unable to be sufficiently familiar with them all to the extent that we can identify specific varieties. For this reason, we are unable to answer your question. We suggest that you contact the Minneapolis Parks and Recreation Board. They would be in a better position to provide guidance on your question. See:

https://www.minneapolisparks.org/

Theoretically giant allium is considered a perennial plant. However, whether it does so is highly dependent on soil type, soil fertility, and environmental factors such as temperature, water availability, and general care. They are capable of self-seeding so via this means, allium may appear in the same location year after year. See the following:

https://www.dutchgrown.co.uk/pages/allium-bulbs-questions-answers - :~:text=Do alliums come back every,will return year after year.

https://www.epicgardening.com/allium-annual-or-perennial/

Over time and a few seasons, provided that the bulb survives from season to season, a single bulb will produce smaller off-shoot bulbs. I have seen this with my own allium. I have planted these off-shoot bulbs and in rare instances, a new plant and flower will emerge. However, this can take several years. The reason is quite simple. Bulbs are a site of energy storage. The amount of stored energy depends upon the amount of foliage produced by the allium in the preceding year. It takes several years of growth before the bulb produces enough foliage so that the necessary energy is stored in the bulb.

Good luck. You are dealing with a beautiful plant. Provide it good care and it will reward you with its beauty. Please contact us if you have further, related questions. Thanks for consulting us.