Ilex

( EYE - lecks )

At-A-Glance Information

Commonly called Holly, Ilex is a diverse genus filled with species of evergreen and deciduous shrubs and trees that need full sun to partial shade and regular water to perform well in the garden. They will attract birds to the landscape with their bright berries. Nearly all Ilex plants are either male or female, and both must be present for female plants to fruit. There are male-female grafted plants available that are becoming more common to avoid this fruiting setback. Use Holly in the landscape as a groundcover, privacy screen or dense hedge, intruder-deterrent barrier, or simply as a specimen in mixed beds or shrubberies. Take care when planting this shrub in the yard, as plant parts are toxic to humans and pets if ingested.

Ilex Species and Varietals

The genus Ilex is the only living member of the plant family Aquifoliaceae and includes three subgenera and over 570 species. Holly growing zones vary by species; for more information see the descriptions below. To find your zone, click here: Zone Map.

Ilex aquifolium (English Holly, Common Holly, European Holly)
This evergreen shrub or tree grows in USDA hardiness zones 6-9 or Sunset growing zones 4-9, 14-24 and H1. This native of Southern and Central Europe and Great Britain is a slow-grower to 40 feet tall and 25 feet wide. There are many varieties that vary in leaves and fruits. This species and its cultivars are resistant to Oak Root Fungus. This species is considered highly invasive in California and the Pacific Northwest (United States). Varieties are outlined below:

'Gold Coast'
Gets to 6-8 feet tall, male variety. Has variegated, gold-edged leaves.

'Ferox'
(Hedgehog, Porcupine Holly)
Male with sterile pollen. Leaves are twisted and covered in spines.

'San Gabriel'
Has seedless berries, without pollination.

'Argentea Marginata'
Has silver-edged variegated leaves.

'Ferox Argentea'
With silver-edged variegated leaves.

'Aurea Marginata'
Gold-edged variegated leaves.

'Pinto'
Has variegated, gold-centered leaves.

'Britebush'
Gold-centered variegated leaves.

'Big Bull'
Male variety with large, nearly smooth-edged leaves.

Ilex cornuta (Chinese Holly)
Evergreen shrub or tree that grows best in USDA hardiness zones 7a-9b or Sunset growing zones 3-24. For this species to set fruit, it needs a long warm season. Needs protection from the sun in desert climates. Native to China and Korea, this shrub or tree can grow to 10 feet or taller and just as wide. Long-lasting berries are notably large. Those that set fruit can do so without a male present. This species is considered invasive in the southeastern and Mid-Atlantic regions of the United States. Check out the species cultivars below:

'Burfordii'
(Burford Holly)
Gets 15 feet tall and 10 feet wide. Almost spineless leaves; useful as an espalier.

'Carissa'
Dwarf variety, gets to 3-4 feet tall and 4-6 feet wide. Small leaves, good for containers. Berry-less.

'Dwarf Burford'
('Burfordii Nana')
Compact - 6 feet tall and wide. Light green, spineless leaves.

'Needlepoint'
10 feet tall and 12 feet wide. Has twisted leaves with bright red berries.

Ilex crenata (Japanese Holly)
This evergreen shrub or tree grows in zones 4-9 and 14-24. Native to Russia, Japan, and Korea. Has a dense, erect habit and mimics Buxus in looks. Gets 4-10 feet tall and wide, and has black berries. Great for hedges, especially useful for this purpose in cold-weather regions where other hedge plants cannot be used. This species also contains some varieties that are great for topiary. Japanese Holly is considered invasive in the Mid-Atlantic and northeastern regions of the United States. See commonly grown varieties below.

'Compacta'
Rounded shrub that reaches 6 feet tall and wide, with a dense habit.

'Convexa'
Another compact shrub, 4-6 feet tall and wide. Great for hedges.

'Drops of Gold'
3 feet tall, 6 feet wide. Has yellow outer leaves and green inner leaves.

'Helleri'
1 foot tall and 2 feet wide for many years after it starts growing, but can reach twice that size in about 30 years.

'Sky Pencil'
This variety has a columnar growth habit, and reaches about 6 feet tall and just 10 inches wide.

Ilex x meserveae (Blue Holly, Meserve Holly)
Evergreen, to 10 feet tall and wide. Prefers USDA hardiness zones 5-9 or Sunset growing zones 3-9 and 14-17. Most plants in this group are sterile hybrids between Ilex aquifolium and a more cold-tolerant species native to Japan. It represents the hardiest of Hollies. Stems are purple and spiny leaves are glossy and blue-green. Varieties are outlined below.

'Blue Boy'
Male variety.

'Blue Girl'
Red-fruiting female variety.

'Blue Prince'
Male variety.

'Blue Princess'
Female variety with red fruits.

'Golden Girl'
Golden berries; female plant.

'Castle Wall'
Columnar variety. 8 feet tall, 4 feet wide. Shiny, dark green leaves and red berries.

Ilex glabra (Inkberry, Gallberry, Bitter Gallberry, Appalachian Tea)
This evergreen shrub grows best in USDA hardiness zones 5-9 or Sunset growing zones 2b-24. Native to eastern North America, this plant produces spineless dark green leaves and black berries. Varieties include 'Compacta' (dwarf variety, female, 4 feet tall and wide, good hedge), 'Nordic' (dwarf variety, male, 4 feet tall and wide, good hedge), and 'Shamrock' (5 feet tall and wide, black berries).

Ilex vomitoria (Yaupon, Yaupon Holly, Cassena, Cassina, Evergreen Cassena, Indian Black Drink)
Evergreen shrub or tree that grows best in USDA hardiness zones 7-9 or Sunset growing zones 3-9, 11-24, H1 and H2. A native of the Southeastern United States, this species can take alkaline soils better than other hollies. Gets 15-20 feet tall and 10-15 feet wide. Does well with shearing, and can take on a columnar shape well; great for topiary specimens. Scarlet berries are produced after flowers fade. Cultivars are listed and described below:

'Nana' (Dwarf Yupon)
3-5 feet tall and wide. Refined and attractive; great for sheared hedge. Fruit is often hidden in leaves.

'Pendula'
Weeping habit, Male and female forms are available.

'Stokes' (Stoke's Dwarf)
3-4 feet tall and wide, Dark green leaves; male species.

Caring for Ilex

Take care when planting this shrub in the yard, as plant parts are toxic to humans and pets if ingested. Plant Ilex, or Holly, in early spring a space in the landscape that receives full sun to partial shade; ideally, they appreciate between 6 and 8 hours of sun each day. When Hollies are grown in less light, they will not flower or fruit as well, leaves will become dull, and overall growth will be stunted. Full sun exposure is especially important for cultivars with variegated foliage. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 4.5 and 6.5 (acidic to slightly acidic). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention.

Water new plantings regularly as they establish a strong root system in their new home. At maturity, these plants perform well in consistently moist soils, though they will develop root rot issues in waterlogged conditions. As a general rule of thumb, water whenever the top inch of soil feels dry to the touch. Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season, and remove flower inflorescences or berries on species which are known to be invasive in the area. These shrubs are very long-lived perennials, able to survive in the landscape for between 50 years and a few centuries.

Caring for Ilex in Containers
Holly shrubs are wonderful in the ground, but can also be grown in containers. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Ilex plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Ilex can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:

Propagating Ilex by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In winter, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch (making your cut just below a node). Because the shrub is in its dormant phase, it should have no leaves on it (unless it is an evergreen variety, in which case remove all but the top two leaves). Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (or the spring afterwards if it is not growing quickly enough), when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Ilex by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seeds are contained inside the red (or black) fruits on the plant and will need to be removed to be planted. Either rub the seeds on a fine mesh grate or cut them open and remove the seeds, and then rinse them and set them out to dry. Once dry, the seeds can be stored in a cool, dry dark place until you are ready to work with them.
Ilex seeds need to be treated before being sown. Mix together horticultural sand (50%) and peat moss (50%). Then in a separate container, mix seeds and the mixture at a ratio of 1:2 or 1:3, respectively. In a third container, place some stones (enough to cover the bottom of the container) and place the seed mixture on top. Then, fill in with more mixture until it is at the same level as the stones (it should be about 2 inches more of the mixture). Place the pot in a dry, cool, shaded area outdoors for 18 months. This allows enough time for the hard coating on the seeds to break down and allow moisture and nutrients to reach the embryo.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination can take as many as 2-3 years from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Holly seeds are contained inside of the fruit produced by the shrub. Both male and female shrubs need to be present in most species to produce viable seeds.

Ilex seeds.

Problems and Pests

Certain species of Ilex are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Ilex, or Holly, shrubs can be susceptible to developing issues with the following pests and diseases in the landscape: