Ilex or holly is a large genus of shrubs with over 550 recognized species. These flowering shrubs can be evergreen or deciduous, depending on the species.
Native to temperate and subtropical regions worldwide, the most diverse range of species are found in the Americas and parts of Asia. Although holly is a flowering plant, it is one with insignificant flowers.
In Europe, the genus is limited to the most common species. Ilex aquifolium is the classic holly and has bright red berries.
The berries, which are technically drupes, appear during the winter and are often seen in Christmas decorations. The red, holly berries are depicted on festive, winter greeting cards.
The word Ilex is Latin and is translated as oak. Holly was originally classified by Carl Linnaeus as a species of oak (probably because the shape of its leaves resemble those of the oak).
Studies from fossils show that species of holly have existed for over 50 million years
|Height||Up to 60 feet (18 m)|
|Width||Up to 20 feet|
|USDA Plant Hardiness Zone||Zones 6 to 8 (certain varieties 5 to 9)|
|Native to||Worldwide, subtropical and temperate regions|
|Plant specific features||Winter berries, evergreen foliage|
How to Plant and Grow a Holly Bush
Where to Plant
Choose your planting site with care – a holly bush can grow up to 60 feet tall if left unpruned. Holly doesn’t like to be transplanted as its roots dislike disturbance, so it is a good idea to find somewhere where it can be left permanently.
Make sure that you dig a hole that is at least twice the size of the root ball of the container. This will give it ample room to spread its roots.
If you are using holly plants to create a hedge, then they need to be well-spaced, and no closer than 10 feet (3.05 m) apart. It is also important if using multiple plants that you select both male and female plants. Whilst both genders will produce the flowers, berries will only form if the flowers are pollinated.
Holly doesn’t have to be planted as a hedge of multiple plants. It is equally good to grow as a single specimen plant for architectural interest.
It can be trimmed and shaped as desired. In common with box or yew, holly is a good subject for topiary. It is slow growing and with its evergreen leaves can be clipped successfully.
When to Plant
The best time to plant a holly bush is after the danger of frost has passed. In the Spring, you can plant a container-raised plant successfully.
Whilst Spring is the preferred time to plant holly, you can also plant in Autumn. Always avoid planting a new shrub during periods of extremes in temperature, such as in the Summer or Winter.
Extreme weather will stress the plant at a time when it needs to focus its energy on developing a strong root network.
Most species need to be around 3 years old before they produce their iconic red berries.
Holly Shrub Care and Maintenance
The good news is that holly bushes are relatively maintenance-free. Without a lot of fuss, they will reward you with their attractive, glossy evergreen foliage and bright red, winter berries for a long time.
Holly prefers soil that is slightly acidic, but it is not too fussy. It’s important to plant in soil that drains well.
Once established, the holly is considered drought-tolerant. It prefers drier conditions. Nevertheless, it is essential that a newly planted holly shrub is watered regularly during the first growing season.
This will help the shrub to develop a strong, robust root network that will enable it to survive periods of drought later on.
The evergreen foliage will be glossier if the holly receives water regularly. Keep the soil moist but not wet. An annual mulch application can also aid in moisture retention of the soil, but make sure that any mulch does not come into direct contact with the stem of the holly.
Choose an ericaceous fertilizer, suitable for evergreen shrubs. An application of a slow-released product can be made once a year in early Spring.
An organic mulch, if used, can also be applied annually. But don’t let the mulch touch the stem or trunk of the shrub, or there is a risk that it will encourage root rot.
Find a planting site that receives full sun for at least part of the day for the best results. The more sunlight, the more berries your holly will produce. However, a holly bush will still thrive if planted in dappled shade.
If you are in a region that receives long periods of strong, afternoon sun, the holly may need some protection to prevent leaf scorching.
Pruning and Repotting
Holly is a plant that doesn’t like to be replanted. Its roots dislike disturbance, so if possible avoid repotting or transplanting the shrub.
Ilex can grow up to 60 feet tall, so you may wish to prune it! As well as in height, a holly bush can also grow very wide. If you need to prune holly, then do so in the winter, during the plant’s dormant season.
If you are growing holly as a subject for topiary, then you need to trim it more often. Trim the growth at least twice a year. This will prevent the new shoots from becoming straggly and spoiling the desired form and shape.
You can grow holly from seed, but the most usual method of propagating this shrub is from cuttings.
Select pieces of the stem from your evergreen holly shrubs that are around 6 inches (15.24 cm) long. Apply hormone rooting powder to accelerate the rooting process.
Take the hardwood cuttings (pieces of stem that have turned woody) from the current season’s growth. The best time to remove the cuttings is during the winter. At this time of the year, the plant will be in its dormant season.
Take the cuttings from the plant by cutting just below the bud, where the leaves meet the stem. The cuttings should ideally be around 6 inches (15.24 cm) long. Remove all the leaves on the pieces of stem, apart from the top two sets.
These leaves should be cut in half. This helps the cutting focus on developing its root growth rather than sending up nutrients and moisture to the top growth.
Ideally, find a place in the garden that you can use to root and grow on your evergreen cuttings. Plant in a sandy medium, that drains well and is not in direct sunlight.
During Autumn and if the winter is dry, the cuttings will need daily watering. Once the ground is naturally damp, you should reduce the watering and probably stop watering until the Spring.
Keep the cuttings in this nursery bed for a full growing season, water regularly, and by the following Spring, they will be ready for planting out into their final growing positions.
Pests and diseases
Provide the Ilex with good growing conditions, and any pest or disease problems should be minimal. Its thick, spiky leaves are not appreciated by deer.
The key to prevent fungal disease is to provide a planting medium that drains well. If the holly bush is left to stand in water, its roots will rot and there is a strong likelihood that the shrub will die.
Poorly draining soil, particularly if combined with warmth, will encourage the growth of fungi that can cause other fungal diseases, such as leaf spots. Reduce the humidity around the base of the plant, by improving airflow.
Any pest issues are unlikely to cause serious damage. You can use an organic pesticide to remove any pest infestation by insects such as spider mites, scale insects, or leaf miners.
Temperature and Humidity
If the holly is subject to excess humidity, the fungal disease can cause concerns. This is a shrub that prefers slightly dry conditions, so be sure to retain a good airflow around the stem and lower parts of the plant. Remove dead wood and other vegetative material promptly.
Other Uses for Holly
With its sharp, prickly evergreen foliage, holly provides birds with important protection from predators. The berries are a significant food source for small mammals and birds during the winter months.
When they first appear, the berries are unpalatable due to their hardness and bitter taste. But, once they have been subjected to several frosts, they soften, and the bitterness mellows.
The berries contain various substances that are toxic. If ingested, they can cause stomach and intestinal damage, and just 20 berries can be fatal to small children. The leaves as well as the berries can also be toxic, but they are less likely to be ingested due to their prickly nature.
The leaves from certain Asian species of holly are used to make a tea-like infusion, and the berries to make alcohol or eau-de-vie.
Most commonly, holly species, hybrids, and cultivars are used for garden decoration, some of which have been awarded the Royal Horticultural Society’s Award of Garden Merit.
Holly is a popular choice of plant for a hedge, with sharp, prickly leaves forming a barrier that is dense and difficult to penetrate.
Holly has religious significance in certain cultures, particularly at Christmastime. It is also used to symbolize truth in Scandinavian heraldry.
Types of Holly You Can Grow
Highclere holly, and Blue Holly are both very popular hybrids.
Blue holly (Ilex x meserveae) is a dense and vigorously growing, evergreen shrub or small tree that can reach around 15 feet or 4.5 meters in height. It has distinctive blue-green foliage and bright red berries.
Highclere holly (Ilex x altaclerensis) will grow as an evergreen shrub or small tree, but remain at around 15 feet (4.57 meters) in height. The glossy leaves are usually not prickly.
English holly (Ilex aquifolium) is one of the most popular holly bushes and this is the variety with the bright red berries, that will symbolize Christmas in your garden. Unsurprisingly, this variety is also known as Christmas holly, but also as European holly, and simply, common holly.
American holly (Ilex opaca) is a popular substitute for English holly and is similar in appearance with spiky, glossy green leaves and bright, crimson berries. This evergreen can grow up to 60 feet (18.29 m) tall but usually stays at around 35 feet (10.67 m).
There are a number of varieties of American holly that can be useful. “Canary” will produce yellow berries instead of the more usual red fruit. “Croonenburg” is self-pollinating, with male and female flowers on the same plant. This makes this variety a useful choice if you only have space for one specimen.
American holly can replace English holly in regions where the latter does not thrive.
Another possible choice, if space is limited, is a dwarf holly. These dwarf cultivars can also be used for ground cover, as low-growing hedges, or planted in containers.
There are many small cultivars available to choose from. Most will remain dwarf, not growing to more than around 8 feet in height, and some even smaller. Not all dwarf hollies produce berries.
The addition of holly in your planting scheme is a great way to bring color and wildlife to your garden during the bleak winter months.
With so many varieties, hybrids, and cultivars to choose from, you will definitely be able to find one to include in your planting scheme.
*image by DenysKuvaiev/depositphotos