Answer: Evergreen shrubs and trees fall into two categories; needled and broadleaf. Since you prefer something that flowers, we'll concentrate on broadleaf evergreens. In a 5-8 gallon container, you'll have best success with a shrub rather than a tree. How about Viburnum rhytidophyllum. It produces white flowers in the spring which turn to scarlet fruit in late summer. A second suggestion is Escallonia, with glossy green foliage and spikes of pink flowers in late summer. You might also be interested in Myrtus communis which produces fragrant and fluffy creamy white flowers in the summer. A final suggestion is Philadelphus (mock orange). It's deciduous, but the sweetly-scented flowers are long-lasting and the shrub itself is quite attractive, even when not in bloom.
Hope the above suggestions help you choose just the right plant!
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