You simply can't go to the garden store and randomly choose plants as there are many things to consider such as light conditions, soil conditions and surrounding plants.
A well planned garden will have plants that thrive and compliment each other but a randomly chosen garden will look haphazard and may even be bad for the health of your plants.
Before you purchase your plants evaluate your garden for how much sun and shade it gets and in what areas.
Consider whether the soil is well drained or has standing water and whether it is sheltered or windy.
Then when you go to the garden store, buy only plants that will thrive in your garden; shade-loving plants for the shady areas, sun-lovers for those sunny spots, swamp plants for areas with poor drainage anddrought-resistant plants for those areas that don't stay wet enough.
Another thing that many gardeners fail to consider is the PH of the soil.
Is your soil acidic or alkaline? Most plants prefer soil that is a bit on the acidic side, but there are some that need alkaline soil to grow.
You ca change the PH level of your soil, but it's just easier to buy plants that like the PH of the soil you already have.
Another thing to consider is how and where to plant your plants.
Do you want a lot of greenery or a splashy show of colors?Narrow down your choices of plants to just a few and buy many of each kind.
If you plant 'one of everything' your garden may seem rather spotty.
Planting in groups is much more aesthetically pleasing as well as harmonious.
One thing you might try is to draw out your garden on a piece of paper.
This doesn't have to be a masterpiece painting just a simple sketch.
Get some colored pencils or even crayons and add the colors of the flowers you want to plant.
Are the colors pleasing together?If so you have a plan, if not it's back to the drawing board.
Before planting, you can put the plants around the garden bed in their pots to see how they will look.
This will allow you to move them around and rearrange until you get the look just right.
Grouping of plants in odd numbers look best so try putting groups of 3 or 5 of the same plant together.
Combine colors and textures to add interest and always put the taller plants in the back and shorter ones in the front.
If your garden can be viewed from all sides as opposed to being up against a fence or house then put the taller plants in the center.
One final consideration is the blooming season.
Many plants only bloom for a short period of time so if you want continual color all season you will have to grow plants that flower during the different periods of the season.
Plant flowers with different bloom times next to each other and you will always have a flower blooming in that spot in the garden.
Also, don't forget the foliage.
Many flower plants have silver, grey or purplish foliage that is just as attractive as the flower.
This means that they are still attractive well past the blooming season!