How do I get a bird of paradise to bloom?

~have you checked to see whether it is pot bound~what size pot is it in?Have you changed the compost in this time?
I bought a large one from Burncoose two years ago and put it in my greenhouse kept at 10 degrees over the winter and only watered now and then until it got warmer and it flowered with 4 huge flowers May /June last year~it is in in a fairly large pot and the leaves are about 5 feet high.
Is any of this helpful?
If you are an RHS member you can write to them for advice enclosing details plus photos etc so they can make a diagnosis and help you.
I have seen them growing in gardens in Capetown with lots of flowers but the temperatures there are up to 40 Degrees Celcius! Maybe it hasn't been warm enough outside?

Strelitzia like being rootbound so I don't think that will be the problem having not been repotted for so long.

You could try and stop feeding it for a while as they thrive in poor soils. I also read that they need cool night temperatures to flower also.

This is taken from PlantzAfrica website
How to grow Strelitzia reginae

Strelitzia reginaeStrelitzia reginae is an easy plant to grow in the garden. Plants do well in full sun to semi-shade, love a rich loamy soil and plenty of water throughout the year. They respond well to regular feeding with a slow release fertilizer and compost. They are however very tolerant plants and will thrive in most soils and can survive with very little water once established. The plants are also wind resistant and grow well in coastal gardens. Strelitzias are sensitive to cold and would need a sheltered position in areas with frost as the flowers and leaves are often damaged by frost. In very cold climates it is better to grow them in pots that could be moved indoors when freezing temperatures are expected.
Propagation is by seed or division. The plants are slow growing and large clumps that are split or moved will take about two years to re-establish and flower again. From seed, plants given ideal conditions will flower within 3 years. To get a mature flowering plant from seed takes about three to five years. For best results sow fresh seed in spring. Before sowing, remove the bright orange tuft of hairs attached to the seed (aril of each seed) and soak in a aqueous solution of ethrel at a concentration of 2000 ppm active constituent, for 48 hours. In practical terms this entails making up 6ml ethrel (39.5% active ingredient) to a litre of water. Sow in seedtrays filled with a well-drained soil medium at a depth of 1,5 times the size of the seed. A constant temperature of 25 C is most suitable for germination as low temperatures retard germination. Germination takes four to eight weeks. Seedlings should be a good size before transplanted (two to three leaves) into a well drained medium. Young strelitzia plants must be grown in shade, for the leaves tend to burn in direct sunlight. Regular repotting allows the young plant to develop rapidly. Restricting the root development retards growth.

Growing Strelitzia
Taken from www.squidoo.com

How to keep and grow strelitzia or bird-of-paradise plants

Growing Strelitzia plants indoors
The photo above is one of my indoor bird-of-paradise plants. This is now ready to harvest more seed again. Over the last number of years I have managed to harvest seed from my plants and grow more from this seed. In this lens I will attempt to give a few pointers to doing this successfully. I am living in Ireland, and our climate is northern temperate, which in short means we get frost and cold in winter and temperatures from -4 degrees centigrade in winter to the low 20's in summer. The Strelitzia are a tropical plant and don't grow naturally in these conditions.
Tips for growing strelitzia and other exotic plants in a temperate climate
Overwintering:
Stop feeding the plants to allow them to become dormant.
One of the main points with the exotic plants is to avoid frost.
Do not overwater in the dormant season/winter. Wet soil is cold soil.
Keep in a well lit area and/or use daylight lamps to ensure enough photosynthesis takes place.
Springtime:
Feed the plant well once growth starts again. Feed regularly throughout the growing season but do not over-feed otherwise your plants will just grow foliage and no flowers.

My own plants came from seed grown in the airing cupboard. From seed to first bloom took four years. My plants are now 12-14 years. Larger plants will happily survive to -6C provided compost is dry between November and March.

Two possibilities in my view
1) You may have a 'flowering runt' that will never flower. It happens.
2) But more likely IMO your compost could be stagnant. Tip your plant out. It may just be all root and no soil in which case a larger pot and fresh compost could well see it flower this summer.

Don't put your plant in partial shade as you explain. Leaving it outside, even during the summer, will provide what it thinks are chilling draughts. Your plant is tropical and our northern latitudes can never provide enough light/heat. They like to bask in hot sun in a high humidity atmosphere. Best in a conservatory/greenhouse.

Mine is in an unheated greenhouse over winter and I have found that it makes its flower spike at the end of the summer before, then it waits until about May, when the spike starts to extend and then flowers. I put it outside over the summer. Repot it, feed it with tomato food from Spring onwards and keep your finger crossed. Mine was raised from seed and flowered after 5 years or so. Persevere, as you feel so proud when it does flower! (You could also cheat in the meantime and buy some fake flower spikes and stick them in the pot too!!)

~just realised you are not in the UK and that we have no idea what temperature range applies in Minnesota!
However there is a lot of good advice from all of us here so I hope some of it is useful!