Plan ahead. Before you can properly plan for your outdoor plants, you must plan the arrangement of your outdoor plants. Take the time to go to your local nursery, bring pictures or sketches of your yard and speak to the staff about what you'd like to accomplish. Then listen to their suggestions. Things that need to be considered are the amount of sunlight each area will receive, soil type and the amount of rain or watering the plant can expect on a regular basis. Also, if this is a plant which will survive in the winter months in your area of the country.
Plant by instructions. Plant each outdoor plant according to the care instructions found on the packaging. While you can probably deviate slightly from the nursery suggestion, your landscaping will appear most vibrant if you give the plants proper room for growth and light.
Be consistent. Many people make a big "to do" about planting and landscaping at the beginning of the season and then slowly their appetite to keep up with the work deteriorates until all of their hard work looks like a giant mess. When you plan your garden or landscaping, be sure that you will have the ample amount of time required to maintain each outdoor plant. Then once your plants are in the ground, set a schedule for watering either by timer or by making a promise yourself to do it. (Maybe even make it a chore for one of your children.) If you do not have the time, hire a gardener. While they can be somewhat pricey, it will still be cheaper than having to redo the entire landscaping.
Research new methods. Another way to care for your outdoor plants is to stay up to date on the latest pesticide sprays and watering techniques the pros are using. Check out gardencomposer.com or gardensalive.com. On these sites you'll be able to learn and emulate the must up to date practices.
Trim them! Most plants need to be trimmed or cut back in order to successfully grow. Don't overlook this task as it too can ruin your outdoor plants. Either pick a day about once a month where you inspect your outdoor plants for trimming or hire a gardener to do it for you. A few hours a month goes a long way to caring for your outdoor plants!