Answer: Sometimes gardeners are able to start an orange tree using a seed taken from an orange. Plant it in a pot filled with seed starter mix, keep the soil slightly damp and set it in a warm spot out of direct sun until it germinates.
However, the resulting tree will never do well in a container. The seed grown trees are large sized and soon become stunted in a container situation. Also, the fruit is different from and usually not as good as the orange the seed came from. This is because the commercial orange trees are hybrids.
If you would like to grow a citrus tree in Chicago, you will need to grow it as a container plant so it can be brought indoors in the winter. I would suggest you grow a variety that is grafted onto a dwarfing root stock (usually Flying Dragon) and suited to container growing such as the Calamondin orange.
Here is more information about container citrus and caring for them that you may find interesting. You may need to cut and paste the complete url into your browser to make it work correctly.
Good luck with your project!
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