Look for healthy green leaves. Leaves are the power generators that supply energy for growth. Plants with weak leaves cannot get off to a good start in your garden. Yellow or brown leaves also can indicate disease. Next, look for strong stems.
Healthy plants are branches, with more than one shoot per stem.
Finally, choose plants that are not in bloom. While it's very tempting to choose a plant with flowers on it, flowers require much of the plant's resources. It won't be able to grow as many new roots or send up as many new shoots. Most bedding plants sold now have a plastic tag with a color photograph of the blooming plants. Use this picture to see what the flowers will look like, and buy plants without flowers.