There is a saying ' right plant, right place' and it is one that gardeners know to be true. If you place a plant - be it a flowering ornamental or vegetable, in the wrong place, it will not thrive.
Although we grow them for our own use, plants have evolved to make the most of a huge range of environmental niches, each with differences. So, a plant which suits high rocky scrub will not do well in damp, peaty soil and one which has developed ways to combat a lack of water will not grow where the soil is full of the stuff.
So, to grow an easy flower garden first assess your soil for pH and type and then make some notes on the microclimate of the area you want to grow the plant in. It is shaded, sunny, sheltered, windy, damp, dry and so on?
Then you need to decide if you want your flower garden to last a year, 2 years or several years or to be a mix with some allowance for changes but some permanent members of the planting group. Make some quick sketches of the lay outs with approximate heights. Do you want the area to be flowery all year round or do you want it to look spectacular in spring, summer or for a special event? For quick colour and interest, annuals are best and they come in a huge range of colours, sizes and shapes. You can sow them directly into the ground if they are hardy annuals, or start them indoors first if they are not. Biennials will flower earlier but you will not get flowers the first year. Perennials come up year after year but they are semi-permanent members of the garden so you need to chose with care and thought.
Then, use directories to see which plants suit the site and fulfil your needs in terms of size and flowering time. You will probably come up with a list of many potential plants. Reduce the size of the list by selecting for colour and foliar interest . Also, check the care of the chosen ones and, if you want an easy flower garden, remve those which require a lot of maintenance like staking, dead heading and so on. Then, make sure you can get them in your area or by mail order and prepare the soil.
Dig, firm and rake so the new plants or seeds have good contact with the soil. Water the plants or seeds in and be patient. Growing an easy flower garden takes time, if only for the seeds to germinate or the plants to really take off.
The right plant in the right place will grow well and fulfil its function. If you choose carefully, do the preparation and plant your plants correctly, you will have an easy flower garden to enjoy for along time to come.