Answer: Unfortunately, you may have made a little mistake with the caladiums and hostas. These two plants require shade to partial shade and would do well on the north or east exposure or in dappled light under trees. They will not tolerate full hot sun. Cannas on the other hand love sunshine and heat. If you have already planted them, you can transplant them to better locations.
The hostas are winter hardy and will live for many years, the cannas and caladiums however will need to be dug up each fall and stored for the winter if you want to keep them from year to year. If you are not ready to make a shady planting area, the hostas and caladiums can be grown in containers for the summer and look very nice that way. Fall is a great time to plant and the hostas should really be planted in the ground before winter because their roots may not survive the cold in an exposed container.
Annuals from seed would be the least expensive way to start your sunny flower bed: you could try marigolds, zinnias, sunflowers, tithonia, cosmos, amd morning glories. If you would like to get started with perennials, inexpensive small plants of purple coneflower, black-eyed Susan and daylily (hemerocallis) would probably grow and mature quickly enough to bloom for you this year and then return reliably from year to year. As a rule perennials bloom only for a few weeks but they do come back each year and in time can be easily divided or otherwise propagated to make more plants if you have a large area to fill.
Your flowers will do best if the soil has been prepared with ample amounts of organic matter such as compost and then any additional amendments (for example fertilizer) added as indicated by the results of soil tests.
Mulch is very helpful in keeping down weeds and conserving moisture and will feed the soil when it breaks down, too. A layer several inches thick should be maintained year round. Place it over the root area and close to, but not touching, the stems of your plants.
Flowers generally bloom best with adequate water. Depending on the season, you may need to supplement natural rainfall. Watering can be important in keeping the soil evenly moist (but not sopping wet) during dry spells. When you water, water deeply to encourage deep rooted plants. A deep watering less often is preferred over a daily sprinkling. In a flower garden or shrub bed, water is applied most efficiently at the roots rather than by sprinkler. Use your finger to dig down a bit and check the soil and see if and when you need to water.
Your county extension should be able to help you with the soil tests and interpreting the results. You will want to know about your soil in planning your lawn care and other landscaping tasks as well.
Since you are new to gardening you may want to look at a book or two. The Dummies series includes a number of excellent books on gardening, full of practical advice that is easy to follow and will help you get great results. They are in most bookstores and many libraries carry them as well.
Enjoy your flowers!
Q&A Library Searching Tips