Holly: all about planting & care of the shrub
Holly is especially popular during the Christmas season. We present the most popular holly varieties, reveal whether holly is poisonous and give tips on planting and care.
Holly (Ilex) brings colour to the garden even in winter when many trees and shrubs have long been bare. With their shiny leaves and red, yellow, black, rarely brown, or green fruits, holly makes a popular ornamental shrub and hedge plant. Holly sprigs are a popular Christmas decoration in the US and here too. However, centuries before this custom arose the Druids considered the holly a sacred plant and the Romans assigned it to the God Saturn and gave away its branches on its holiday, the Saturnalia. According to traditional folklore, a living holly protects the house and yard from lightning and so it is best not to cut it down too much.
- Holly origin and properties
- Various types of holly and species
- Planting holly
- Holly care
- Propagating holly
- Overwintering holly
Holly origin and properties
Holly (Ilex) forms the only genus in the holly family (Aquifoliaceae). There are an estimated 600 species worldwide. Holly trees inhabit all climate zones on earth, but their biodiversity is greatest in South Africa and East Asia, where they can still be found at altitudes of up to 2000 metres above sea level. Only four of them are native to Europe, the best known is certainly the European holly (Ilex aquifolium).
Holly is a deciduous or evergreen deciduous tree that can grow up to 25 metres tall. It is also not uncommon for individual Ilex shrubs to live up to 100 years old. The leaves are arranged alternately on the long, often branched shoots. Depending on the species, the leaves are smooth, toothed, or thorny at the edges. They are leathery and dark green or green with yellow or white variegation.
Holly flowering time
Holly plants are dioecious. This means that a shrub bears either only female or male flowers. These are inconspicuous, small and can be cream, yellow, white, green, or even almost purple and are located in the leaf axils of last year’s shoots. The flowering time of Ilex can vary depending on the species. The native Ilex aquifolium blooms between May and June. Depending on the variety, fruits of different colours can develop, but the spherical drupes are usually red.
Is the holly poisonous?
Holly sprigs and berries are highly toxic to humans and animals. Poisoning can quickly become very dangerous, especially for small children. Symptoms of poisoning are vomiting, nausea, diarrhoea, and circulatory problems. If any part of the plant has been swallowed, plenty of fluids, preferably water or tea, need to be consumed immediately and seeking medical attention is essential.
The shrub is also extremely poisonous for dogs, cats, and other pets. However, the risk of animals nibbling the plant is low because the leaves are leathery and sometimes prickly. Nevertheless, caution is advised: holly can be deadly for small animals. For birds, however, holly berries are a real feast. In winter, they provide a treat for the little birdies.
Summary: toxicity of holly
- Both berries and leaves are highly toxic
- In case of poisoning, drink plenty of fluids and consult a doctor
- The shrub is especially dangerous for small children
- For birds, the berries are harmless and a popular food in winter
Various types of holly and species
The diversity within the holly family is very large. To help you keep track of the up to 600 different species worldwide, we present the most interesting species and varieties.
Common holly (Ilex aquifolium)
Ilex aquifolium is native to our country, you will especially find the Common or European Holly in mixed forests and of course in gardens. Popular varieties of this type are:
- ‘Alaska’: this cultivar bears solid dark green leaves and can grow many feet tall into a stately tree.
- ‘Heckenzwerg’: this variety takes 10 years to grow 30 centimetres tall. It never grows taller than 50 cm. It is wonderful for low hedges.
- ‘J. C. van Tol’: the leaves of this popular variety are not serrated but have smooth leaf edges. It bears a variety of small, bright red fruits.
- ‘Myrtifolia’: this variety does not bear berries, but its leaves are even more striking. These are namely shiny, wavy, and quite a bit longer than their congeners.
- ‘Rubricaulis Aurea’: this variety stands out with its green leaf centre and a wide, cream leaf margin.
- ‘Silver Queen’: the leaves of this variety are grey green in the centre with a thin, silvery white leaf margin.
Japanese holly (Ilex crenata)
This species, which originated in Japan, is now also popular in our country. What is special about this species is that many varieties look quite similar to the boxwood (Buxus). This is especially convenient for those who are looking for an alternative because of the box tree moth. There are countless varieties of Japanese holly. We present the most beautiful ones to you now:
- ‘Convexa’: the leaves of this variety are light green and curved inward. The fruits are green at first and then turn black.
- ‘Dark Green’: this variety looks confusingly like boxwood. Only the small, black fruits give it away as Ilex.
- ‘Golden Gem’: this variety bears golden yellow foliage when budding. Later, the leaves turn green.
- ‘Green Hedge’: the leaves of this variety are light green with a delicate yellow leaf margin.
- ‘Green Lustre’: this variety grows as a dense, hemispherical bush. The leaves are slightly toothed and green. The fruits are purple, green.
Bushy holly (Ilex x meserveae)
This species of holly bush is particularly popular for hedges. This is due to its upright, conical growth and height of up to three metres. Some interesting varieties of this species are:
- ‘Blue Euro’: this variety stands out for its special leaves. These are light green in the middle of the leaf, becoming creamy white towards the outside, with the leaf tips shimmering purple.
- ‘Blue Prince’: this variety captivates with its blue-green leaves and particularly dense growth. It does not bear fruit because it is a male only plant. The female counterpart bears the cultivar name ‘Blue Princess’ and bears bright red fruit.
- ‘Heckenfee’: this variety captivates with its green, strongly serrated leaves and many decorative red fruits.
- ‘Heckenpracht’: Green, densely toothed leaves bear this variety, which makes any hedge an eye-catcher.
- ‘Heckenstar’: it is with good reason that this variety is called ‘Hedge Star’, as its densely branched and columnar growth makes it perfect for hedges.
Winterberry plant (Ilex verticillata)
An unusual attribute of this shrub is that it loses its leaves in winter. Before that, they turn yellow and orange. They are therefore not evergreen; it is rather rare to come across them in our country. This species originates from North America.
Horned holly (Ilex cornuta)
This species, originally from China, is widespread in large parts of China and Korea, where it is also cultivated as an ornamental plant. This is mainly due to the large, decorative fruits.
American holly (Ilex opaca)
This species of holly is native to the southern and eastern United States. There it is used as an ornamental plant, but the wood is also used in arts and crafts. It is also this species that adorns many living rooms and postcards at Christmas time.
Brazilian tea (Ilex paraguariensis)
Another species of holly that many do not know is also an Ilex is the Brazilian tea, also known as the yerba mate. The leaves of this plant are used to make the stimulating mate tea. In large parts of South America, mate is drunk almost daily. The drink is also gaining popularity in our country.
Holly prefers a bright place in the garden. This can be either a sunny or a semi-shaded location. The soil needs to be rich in nutrients and moist. Acidic and permeable soil at the site is also recommended. Holly can also be grown in pots. For this purpose, select a suitable small-growing variety – or a pot of a corresponding size.
Ideal location for planting holly:
- Bright location
- Moist, nutrient-rich soil
- Acidic and permeable soil
- Also possible as potted plants
Once you have found the perfect location in the garden, you can plant your holly. We have summarised how to do this for you in the following guide.
Step-by-step instructions for planting Ilex:
- Best time: in spring after the last frost
- Water root ball in a bucket
- Dig planting hole: 1.5 times as wide and deep as root ball
- Mix compost or fertiliser with organic long-term effects such as our Plantura All Purpose Plant Food
- Mix soil that is too calcareous or clayey with one-third sand and one-third potting soil
- For container-grown plants: lightly prick the roots with a spade or your hands to stimulate branching. For balled plants, open the ball cloth or wire basket generously at the root neck
- Insert plant deep enough so that the root neck (transition from root to shoot) is above the earth
- Fill planting hole with soil and tread it down with your feet
- In warm weather and with little rain: form a watering rim of soil and carry out a planting cut
- Water well
- Planting distance for hedges: 4 – 8 plants per metre
The nice thing about holly is that once they are planted, they require little care, and can be enjoyed for many years. Normally, you do not need to water the evergreen shrub regularly. Only potted plants need regular watering. Waterlogging needs to be avoided at all costs. Persistently wet roots lead to root rot. The water used for watering will need to be as low in lime as possible because the holly prefers it to be slightly acidic.
Tip: wear gloves when working on your holly bush. This will protect you from its prickly leaves.
Pruning holly trees
The holly tree does not require regular pruning. In general, however, the plants are very tolerant of pruning and can cope with pruning in the spring or summer very well. This can be, for example, selective pruning for topiary or hedges, or to thin out plants that are too dense. Prune carefully and not too much at once, as holly grows very slowly, and it can take a long time for the shrub to grow back to its old shape.
How is holly pruned?
- Best time: spring or late summer
- Very tolerant to pruning
- Shape pruning for hedges or topiary, pruning, or thinning out
- Prune with care, grows slowly
When fertilising your Ilex, you need to consider two things: the shrub likes acidic soil, so low-lime fertilisation is optimal. In addition, the fertiliser needs to be rich in nitrogen. For holly, fertilising once a year is sufficient. The best time for this is in the spring. Use an organic long-term fertiliser for this or horse manure, bone meal or acidic bokashi. Our Plantura All Purpose Plant Food gently provides the evergreen plant with all the essential nutrients over the long term, without over fertilising it.
- Perfect for a variety of plants in the garden & on the balcony
- Promotes healthy plant growth & an active soil life
- Long-lasting fertiliser that is free from animal products - child & pet friendly
There are two proven methods of propagating holly: offshoots or cuttings. Both methods are briefly presented here.
Propagating holly from offshoots:
- In spring or late autumn
- Select a healthy shoot and lower it into the ground
- Where this touches the soil, remove the leaves
- Next, plant the shoot into the ground
- The tip of the shoot must protrude from the soil
- In addition, the planted shoot can be fixed with wire or a stone
- When roots form in the autumn or spring, separate the offshoot from the mother plant
- The new shoot is dug out and planted in a new location
Propagating holly using cuttings:
- Optimal time in July/August, but possible until frost sets in
- Use shoot tips of young plants or branches of old plants growing as close to the ground as possible
- Remove all leaves except the top ones or shorten by half
- Place in a water-draining container with a low-nutrient, airy cutting substrate
- Press down and water generously
- Ideal conditions are found in a mini greenhouse
- Place in a bright location
- Ventilate and water regularly
Overwintering holly is very easy, as the vast majority of holly species are hardy and can survive the winter in the garden without any special protection. Only very young plants or special species need winter protection. A fleece or fir branches are suitable for this purpose. Potted plants need to be overwintered in a bright and frost-free location. This can be, for example, a unheated conservatory or a bright hallway.
Note about risk of confusion: often the holly is confused with the Oregon grape (Mahonia aquifolium). If you discover yellow flowers and dark purple berries on what you think is a holly, it is certainly an Oregon grape.