Answer: Achieving a good looking continuous bloom with a bedding effect is difficult with bulbs and perennials because their length of bloom time can vary considerably from year to year depending on the weather and to some extent on the age of the plants. The choice is further complicated by the fact that there are hundreds (maybe thousands!) of plants to pick from and only so much square footage to plant them in. While the bloom period may last a week, the foliage and/or roots and/or dormant bulbs are still in place all year.
For example, snow crocus and iris reticulata are early blooming bulbs, followed by crocus and other minor bulbs, then numerous classes of daffodils, hyacinths, tulips and so on all the way through the summer blooming bulbs and up to fall blooming crocus. Early perennials include hellebores which may bloom in the snow and stretch on to late bloomers such as Japanese anemones and toad lilies which bloom in late fall.
I think the best way to approach your project is to look at some basic books about bulbs and perennials to find some likely candidates and then look at the plants in the garden to see which ones you actually like best, then block out the sequence using your favorites. Finally, fill in any apparent gaps based on the results from year to year. You might also ask local gardeners which plants seem to do the best in your local microclimate.
Two books to get you started might be "Perennials for Dummies" by Marcia Tatroe (ISBN 0-7645-5030-6) and "Flowering Bulbs for Dummies" by Judy Glattstein (ISBN 0-7645-5103-5).
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