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.
Can You Cut Lilies Down After They Bloom? Spring flowering tulips (Tulipa spp.) produce cup-shaped upright blooms on tall stalks surrounded by blade-like leaves. Most varieties grow well in U.S. Department of Agriculture plant hardiness zones 3 through 8 or 9, returning each year with a fresh round of flowers when provided with proper spring care. Although the flowers are short-lived, the foliage persists for several weeks and requires proper cutting back for the bulbs to remain perennial.