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.
Perennials, or plants and flowers that come back year after year, are found in virtually every yard. Perennial flowers work in multiple situations: in whole garden beds, in combination with annuals and bulbs, as accent to shrubs and trees, and in containers and windowboxes.his easy-to-grow perennial produces colorful globes of blue or white trumpet-shape flowers in summer and fall. Its evergreen strappy leaves add texture to beds, borders, and containers. Agapanthus blooms best in a spot where it gets full sun and has moist, well-drained soil.