• Topics: Environmental Horticulture | Park Brown, Sydney G | Shrubs and Trees (MG, South Florida ed.) | Shrubs and Trees (MG, North and Central Florida ed.) | Holly

Hollies at a Glance¹

Hollies (Ilex spp.) are reliable, low-maintenance plants for Florida landscapes. Diverse sizes, forms, and textures exist, ranging from large trees to dwarf shrubs (Figures 1 and 2). Some hollies can be used as informal or formal hedges or as foundation plants, while others make beautiful accent or specimen plants. Many are valued for their colorful berries, which provide food for birds and brighten the fall and winter seasons. Several hollies are native to Florida. Table 1 lists some of the more popular hollies sold in Florida.

Figure 1. 

The large, weeping form of Ilex vomitoria 'Pendula'.

Credit:

UF/IFAS

[Click thumbnail to enlarge.]

Figure 2. 

The dwarf, compact form of Ilex cornuta 'Rotunda'.

Credit:

UF/IFAS

[Click thumbnail to enlarge.]

Description

Most hollies, including all those listed in Table 1, are evergreen. A few native hollies lose their leaves in winter but are rarely commercially grown and sold in Florida. Hollies are dioecious plants, meaning male and female flowers are located on separate plants. Female plants produce berries (Figure 3); male plants do not. For this reason, nurserymen often propagate only female plants. Male and female plants produce small white blooms in spring. Bees are the primary pollinators of holly flowers and will carry pollen from male plants as far away as 1.5–2 miles, so it is not necessary to have a male holly in the immediate area.

Figure 3. 

Holly berries attract birds and add color to the winter landscape.

Credit:

UF/IFAS

[Click thumbnail to enlarge.]

General Culture

Hollies generally prefer partial shade, but most grow satisfactorily in full sun. Slightly acidic, well-drained soils are essential for most hollies, although a few, like Dahoon holly (Ilex cassine), are native to moist areas and can be planted on wetter sites.

Planting

Container-grown hollies can be planted at any time of the year with proper post-planting care. The planting hole should be 1 foot (30 cm) wider than the root ball and slightly shallower than the height of the root ball. Once planted the site should be watered thoroughly to settle soil around the roots. A 2–3 inch (5–8 cm) depth layer of organic mulch should be added and maintained to moderate soil temperature, conserve moisture, and help control weeds; however, mulch should not be placed over the root ball. Trees and shrubs that are regularly irrigated through the first growing season after transplanting require from 3 months (USDA Plant Hardiness Zones 9–11) to 6 months (USDA Plant Hardiness Zone 8) to become well established. More detailed planting procedures are provided in Specifications for Planting Trees and Shrubs in the Southeastern US (http://edis.ifas.ufl.edu/ep112).

Watering and Fertilizing

Irrigation is necessary to establish newly planted hollies and to encourage optimal growth. Care should be taken not to waterlog the soil since holly roots require good aeration. Established hollies should be watered as needed during dry periods.

Fertilize newly planted and established hollies in March and September if faster growth is desired or when plants exhibit nutrient deficiencies.

Pruning

Hollies may need occasional light grooming to maintain their form. Major structural pruning may be necessary to maintain a single leader (trunk) on a specimen tree or when training plants for special purposes (Figure 4). Detailed pruning techniques are provided here: http://edis.ifas.ufl.edu/topic_tree_pruning.

Figure 4. 

Hollies can be pruned into special forms.

Credit:

UF/IFAS

[Click thumbnail to enlarge.]

Propagation

Hollies are primarily propagated from tip cuttings in order to produce plants with the same characteristics as the parent plant. Cuttings should be 3–5 inches (7–15 cm) long and treated with a rooting hormone. For optimal rooting, hollies require a humid environment to minimize water loss and tissue desiccation. Growing holly from seed takes longer to produce new plants and results in seedlings that do not have the same characteristics as the mother plant.

Pests

Insects and diseases are not a major problem when hollies are selected, planted, and cared for properly. Poor performance is usually associated with inadequate growing conditions, such as poor soil aeration, drought, improper planting, or lack of fertilization.

Infrequent pests include scale, leaf miner, and spittlebug insects, as well as mites. Many different scale insects feed on hollies by sucking plant juices from leaves and stems. A substance called honeydew is secreted by some scales, and a black, sooty mold fungus grows on the honeydew. Although sooty mold does not harm plants, it is unattractive. Leaf miner larvae feed inside the leaf between the upper and lower surfaces. Blotch or serpentine mines appear on the upper surface of infested leaves. New leaves infested with leaf miners are often stunted and deformed. This pest is seldom severe enough to threaten the health of a holly. Spittlebugs are ¼ inch long, black-brown in color, and oval shaped with two orange bands across their wings. They are most common in north and northwest Florida on Ilex cassine and I. opaca plants. They feed on young leaves and stems by sucking plant juices. Leaves often are killed and dropped from the plant. Spider mites can be found on the underside of holly leaves, especially during hot, dry weather. Infested leaves turn gray or brown and fall from the plant. More information on pest management is available from your local UF/IFAS Extension office (http://solutionsforyourlife.com/map/).

Diseases known to attack hollies include stem gall, twig dieback, and root rot. Stem gall, or witches' broom (Sphaeropsis tumefaciens), is a usually fatal disease of hollies in central and south Florida. Stem galls form on twigs and branches, causing the stems to enlarge and initiate an abnormal number of shoots, producing a broom effect (Figure 5). The disease is spread by infected pruning tools, as well as by wind and rain. See Sphaeropsis Witches’ Broom of Holly (https://www.freshfromflorida.com/content/download/11183/143389/pp176.pdf) for more information.

Figure 5. 

Witches' broom disease (Sphaeropsis tumefaciens).

Credit:

UF/IFAS

[Click thumbnail to enlarge.]

Numerous fungi can cause twig dieback, which starts at twig tips and gradually progresses toward the base. Leaves often wilt and drop from the plant. Root rots are usually associated with over-irrigation or hollies planted in poorly drained, wet soils. Poor soil aeration weakens holly roots, allowing fungi to invade and cause considerable damage. Hollies with diseased roots appear weak, and branches, sections, or the whole plant can die. A particular root rot disease known as mushroom root rot can be diagnosed by scraping the bark of large roots or lower trunk tissue. If the area between the bark and the wood shows a white layer of fungal growth, mushroom root rot is involved. Mushroom fruiting bodies may appear in advanced stages of infection. Dead or dying plants affected by mushroom root rot should be removed with as much of the root system as possible, and the soil should be replaced before replanting anything. Fungicides cannot control stem gall, twig dieback, or root rot once these diseases have become established.

Acknowledgements

The author wishes to thank Joe Sewards, UF/IFAS Extension Putnam County horticulture agent, for reviewing this publication and Mary Derrick, UF/IFAS Extension Santa Rosa County horticulture agent, for her help in developing it.

Tables

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.

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