First things first. Is your pot in the shade or in the sun? Obviously this is important. You can't put shade plants in the sun. Everyone should know that. But equally as important is you can't put full sun plants in the shade! Although I will admit that in central and southern Utah, sun can be brutal. And some plants that normally wouldn't take shade, will take a little in Utah.
Next, decide your color scheme. The guy I work for says that Mother Nature just throws out seeds and pays no regard to where they land. Obviously fields of wild flowers are beautiful. But here in the "Pot Head" world, things are a bit different. Pick your colors wisely. Last year I planted pink in all of my pots. Partly because my daughter was with me while I planted them, and she is a pink freak! I have never been a real pink girl. By July, I was already finding reasons not to go out and water my pots.
Once we have chosen shade/sun and colors, we are ready for action!
Fill your pot with "new" potting soil. Most nurseries, and even Wal-Mart will have something to purchase. I choose to support my local nursery. Fill your pot full to the top with dirt, then water it in. This is an important step. When you put water in the pot, the dirt sinks! Make sure that you water your pot well enough that water starts to drain from the bottom drainage holes. (You MUST have drainage holes unless you want an aquarium full of dead plants.) Finish filling and watering down until your dirt line is about an 1 1/2 to 2 inches from the top.
Shopping list for a regular 18 to 24-inch pot: (this will work for Hanging baskets as well)
1 ivy geranium
osteospurmum, coleus, angelonia or licorice vine
The above all work for Sun or Shade. But if in dense shade you could use a Tuberous Begonia in place of the Geranium, keeping the Ivy Geranium. Depending on color choices and shade vs. sun options I choose 4 to 6 of the following plants. On dialogue these plants are represented by a Purple Dot. This is your "color"
Some sort of Trailing Petunia, Supertunia or Wave (sun & shade, Not dense shade)
Verbena (sun or shade)
Trailing Lobelia (sun as long as it isn't full sun, and shade)
Euphorbia (Diamond Frost) (sun or shade)
Homestead (sun & is also a perennial)
Fan Flower (sun)
Fusia (only shade & hates wind)
Million Bells (shade)
Lantana (part sun or shade)
Some Proven winner vines that I love but either have no flower or insignificant flowering
Sweet Potato Vines. Limey for Sun Black for Shade (I love these, wouldn't have a pot without)
English Ivy (shade)
Boston Ivy (both Ivy's come in variegated versions) (shade)
Then I add at least one 3 pack of vines (these ironically are mostly house plants)
These are your "Vines" represented on the dialogue as a light green/yellow dot.
Green Charlie (Sun)
Red Charlie (sun)
Yellow Charlie (sun)
Mary Jean Ivy (shade)
Archangel (my favorite) (sun or shade)
Wandering Jew (full sun)
Green Jew (sun or shade)
Bridal Vale (shade)
Creeping Jenny (sun or shade)
If you use the above recommendations, your pots could turn out like these below. We use the same plants and basic standard chart. Also if you feel like you have a big empty spot, fill it in with a simple vine or another color.
Now for taking care of the pots. If you put this much work into them, you might as well take good care of them. Here are some basic guidelines.
Keep evenly moist. Often in Utah that is daily watering. Pots in the sun will need more water than pots in the shade.
I apply a balanced fertilizer (10-10-10-)at least every two weeks. Fertilizer that completely dissolves in water is the easiest. (miracle grow, but I am not advertising) You can also use a time release fertilizer, but check the package for how often to use. Fertilizing is necessary because the nutrients are flushed through the soil through the constant watering.
Your plant probably receives light more from one direction that the other, turn your pot frequently to avoid lopsided growth.
If you remove dead blossoms your plant will continue growing and giving more blossoms. If the dead flower remains, the plant is putting most of its energy into seeds rather than new blooms and foliage.
Some plants become "leggy" or get huge as the season progresses. You can trim back using sharp scissors or pruners. Cut the stem just above a leaf. You plant will be happier, and produce better foliage.
There are so many variations on pots. You need to find the plants that work for you. If you do or don't use this advise, I hope that it gets you excited to create a beautiful pot for you porch.