Holly plants are well known and common throughout four continents. Although hundreds of different plants are classified as holly, each shares a few common traits that help identify it as a holly plant. Holly has been used for centuries in various parts of the world for livestock feeding, decoration and landscaping.
More than 600 holly plant species exist between bush and tree varieties. These plants are a landscape favorite because of their high resiliency to disease and pests. Holly plants range in height from 6 inches to 70 feet. Holly plants are most often recognized by their foliage and fruit. Leaves are either spined or spineless. Fruit can range in color from yellow to orange to red to black. These plants can be found in many climates and conditions in the soils of North and South America, Asia and Europe. China has 200 of the 600 native species.
Holly plants come in a range of types divided up into two groups: bush and tree. Of the various types within these two groups, English holly is the most commonly identified holly tree. Meserve hollies (blue holly) is the easiest bush holly to grow.
Holly plants can be evergreen or deciduous. The identifying characteristic is the small spikes or thorns at the end of leaves. The berries produced are toxic to humans and can cause poisoning and diarrhea.
Holly plants are common ornamental plants. Larger plants are used as focal points, while smaller varieties are grouped together as foundations for the garden. Holly is used for hedgerows and privacy screens. Birds use larger varieties for shelter, food and shade. Medieval Europeans used the berries to feed cattle. Holly is used during the Christmas season as wreaths or centerpieces; the varieties most used for this purpose are the American and English holly.
Holly plants need lots of sunlight and will tolerate partial shading before the color begins to fade. Old growth needs to be trimmed off in autumn or winter for thicker new growth in spring. Acidic soil is best and should be well draining. Female and male plants must be planted within 30 feet of each other for pollination.
Holly plants are resilient but do have disease problems. Insects are the most common problem and include mites, scale, aphids and leaf miners. Fungal problems can also occur; the most common ailments include tar spot and cankers. Treatments include insecticidal soaps, sprays or destroying affected branches and foliage. Moving the plant or adjusting the soil will help environmental problems, such as poor soil or poor drainage.