A number that is calculated to summarise a group of numbers. The most commonly used average is the mean, the sum of the numbers divided by however many numbers there are in the group. The median is the middle value in a group of numbers ranked in order of size.
Perennials: cutting back. Perennials are not demanding plants, but trimming them after flowering finishes in autumn helps improve their appearance and flowering. However, you can leave some stems over winter to provide homes and food for wildlife, and then trim back in spring.utting back herbaceous perennials during autumn restores order and tidiness to the garden. However, this removes potential winter interest, in the form of height and structure, plus food and habitat sources for wildlife.
5. Plant a tall, upright plant in the center of the urn to create a main focal point for the container garden. Try a spiky ornamental grass, such as purple fountain grass (Pennisetum setaceum Rubrum), which grows as a perennial in U.S. Department of Agriculture plant hardiness zones 9 and 10.ransplant any perennials to your garden at the end of the growing season and discard any expired annuals. You can put the urns in storage until the following spring, or display material such as willow branches in the urns for winter interest.