Clerodendrum: all about varieties, planting & care

Sarah
Sarah
Sarah
Sarah

For me plants are some of the most exciting living beings, even though they live in slow motion. They have fascinating abilities and just so much potential! That's why I studied organic farming. However, since plants are rather thin on the ground in my city, I often spend time hiking in the nearby mountains at the weekend. In the future I would love to run a farm myself.

Favourite fruit: strawberries and gooseberries
Favourite vegetable: courgettes

The Clerodendrum is still relatively unknown in our country. For those who want to be pioneers in terms of exotic shrubs, we have summarised the most important notes on planting and caring for Clerodendrum in the garden.

Dark purple fruit of the Clerodendrum
Even when Clerodendrum have faded, they still hold many surprises. The fruits of the farges harleyquinn glorybower, for example, are a true ornament for the garden [Photo: islavicek/ Shutterstock.com]

With its magnificent flowers and unusual fruits, the exotic Clerodendrum (Clerodendrum) is slowly making its way into European gardens and homes. You can find out why this is, here.

Clerodendrum: characteristics and origin

Clerodendrums are a very disparate group. No wonder, because their spread includes the entire tropics and subtropics of this world. There are both small trees and shrubs belonging to the Clerodendrum genus, as well as herbaceous plants and lianas. But the Clerodendrum has even more to offer. While some species are deciduous, others are evergreen. However, they all belong to the Labiates family (Lamiaceae). The flowers shine in all kinds of colours and are usually extremely fragrant.

Clerodendrum leaves and flowers
Clerodendrum species live mainly on forest edges, in undergrowth or thickets [Photo: Justadust/ Shutterstock.com]

Clerodendrum species

There are many Clerodendrum species. The genus seems incredibly rich in species, wonderfully diverse and even downright confusing. A closer look has revealed that not all of these species actually belong to the Clerodendrum genus. And so there is still a heated discussion about which species belong to the genus and which do not. Currently, the number of Clerodendrum species is somewhere between 150 and 300.

The most famous representative of the Clerodendrum genus is

  • Japanese Clerodendrum (Clerodendrum trichotomum var. fargesii): the Japanese Clerodendrum is a hybrid between shrub and tree. Its shrubby growth is so compact that it almost grows like a small tree. The plant is perfect for small gardens and sitting areas with a maximum height of three metres. It is considered hardy, but should be protected for the first few years. The white-bluish flowers appear in August/September and are arranged in panicles. The red and blue fruits are a real eye-catcher.
Farges harleyquinn glorybower tree
The Farges harleyquinn glorybower tree convinces with its dwarf and compact growth [Photo: Gabriela Beres/ Shutterstock.com]
  • Chinese Clerodendrum (Clerodendrum bungei): with a maximum height of two metres, the Chinese Clerodendrum remains significantly smaller than the Japanese Clerodendrum and has more of a shrubby appearance. It almost resembles a hydrangea, with its wide leaves and spherical pink flowers. In mild climates, the plant is winter-hardy, however in cold temperatures it will freeze back to the ground. However, be careful: once you have found the perfect location, the Chinese Clerodendrum like to spread via root runners. A root barrier should therefore be used.
Light pink flowers of the glory flower
The glory flower tree is similar to a hydrangea in growth and appearance [Photo: Peter Turner Photography/ Shutterstock.com]
  • Climbing Clerodendrum (Clerodendrum thomsoniae): If you have already been on the road in tropical Africa, you may have seen a climbing plant with striking balloon-like puffy white calyxes and red flowers. This liana also belongs to the Clerodendrum genus and makes a beautiful houseplant. Its flowers create an exciting contrast either in a hanging basket or climbing along a trellis. Although the climbing Clerodendrum can theoretically grow several metres tall, its growth can be limited to about one metre. This species is not hardy.
White and red flowers of the bleeding glory bower
The deep red flowers of the bleeding glory bower emerge from pure white bracts [Photo: Viktor Fedorenko/ Shutterstock.com]
  • Ugandan Clerodendrum (Clerodendrum ugandense): the Ugandan Clerodendrum surprises with its beautiful blue flowers. As a tall stem or in a pot, it makes a wonderful addition to the garden or patio. This type of growth is perfectly combined with a good tolerance of pruning. Its leaves are evergreen, so it is better to overwinter it in a frost-free place.
Light blue flowers of the buttefly bush Ugandense
With its blue flowers, the butterfly bush ‘Ugandense’ is something very special [Photo: Sundraw Photography/ Shutterstock.com].

Planting Clerodendrum plants

As tropical plants, Clerodendrums love sun but do not cope well with intense summer sun. In their homeland, they grow mainly at the edge of the forest and in thickets. It is therefore better to plant your Clerodendrum in the shelter of other trees or in a place that is protected from direct midday sun. Clerodendrums kept indoors likewise prefer semi-shaded places in the home. Generally, they love a warm location, preferably with high air humidity. The following conditions are important:

  • Protection from direct sunlight
  • Warm
  • High humidity

The best time for planting is in the spring. Dig a sufficiently large planting hole. It should be wider and deeper than be the root ball itself. Now put some of the soil back into the hole and put the root ball on it in line with ground level. Now fill in the hole with the rest of the excavated soil. This way, your clerodendrum will have an easier time penetrating the soil with its roots. Now press the soil gently so that the plant stands securely on its own, and water it well. The first time after planting, you should continue to water more frequently until the tree has sufficiently developed its roots.

Digging a hole with a spade
Dig a hole large enough for the root ball so that the soil around it is also loosened [Photo: Duet PandG/ Shutterstock.com].

Repotting

Clerodendrum are not very demanding in terms of substrate. They thrive in any well-maintained, well-drained garden soil with a slightly alkaline pH. You can therefore place the Japanese and Chinese Clerodendrum in the garden without much preparation. This is usually just as true for potted Clerodendrums, but since you have a choice here, you should opt for humus-rich garden soil.

Repotting is due about every one to two years. Of course, the growth and size of the plant are also crucial factors.

Clerodendrum plant care

With good care, Clerodendrums can grow relatively old. The Japanese Clerodendrum, for example, grows into a beautiful tree within many decades. In addition, Clerodendrums can be easily propagated by cuttings. So, in principle, their genetics are immortal. To ensure that your Clerodendrum also reaches a ripe old age, we have collected the most important information for you here.

Watering and fertilising

Over the summer, watering should be determined by the clerodendrum’s native environment. It should be quite humid. Accordingly, water regularly and fully, so that the soil always remains moist. However, you should avoid waterlogging at all costs, as this can lead to root rot. In winter, clerodendrums should be kept a little drier. Deciduous species in particular need significantly less water.

Water droplets on white Clerodendrum flowers
Clerodendrum cultivated as houseplants enjoy being sprayed with a little lime-free water from time to time, both in summer and winter. This cleans their leaves and increases the humidity [Photo: JANRUNG SEANFUN/ Shutterstock.com].

Fertilising should also be discontinued during the winter, starting around September. In the spring, however, recently planted specimens love a dose of fresh compost. Alternatively, you can apply fertilisers twice a year, such as our Plantura All Purpose Plant Food. You should make sure that fertilisers have sufficient levels of phosphorus, because this promotes flower formation. So the main points for watering and fertilising are as follows:

  • During the summer, always keep moist
  • In winter, water a little less
  • Regularly spray houseplants with low-calcium water
  • Only fertilise during the warm season
  • Choose natural fertilisers
  • Phosphorus in fertiliser promotes flower formation
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Pruning Clerodendrums

Hardy Clerodendrums usually do not require pruning, as they remain quite compact. If you still want to swing the secateurs, early spring is the right time to do so, before the new shoots. Clerodendrums kept in pots or tubs are more likely to need pruning.

The climbing Clerodendrum, for example, can easily be shortened a little during the summer months. More radical pruning is also possible but should be done in early spring.

Overwintering

Depending on the species, older clerodendrums can be quite hardy. Japanese Clerodendrum is therefore also frequently planted outside in Europe. It requires only light winter protection in the first two to three years. Here, it is helpful to protect roots using fallen leaves or brushwood and to wrap the trunk with fleece or bubble wrap during periods of extreme cold.

Many species, such as the Chinese Clerodendrum or Ugandan Clerodendrum, have a certain winter hardiness and can also be grown outdoors in mild regions of Europe. Protection of the root using foliage or brushwood can be helpful in extreme situations. The above-ground parts of the plants freeze over almost completely in winter. While the Chinese Clerodendrum tolerates this well, the Uganda clerodendrum should be overwintered in a frost-free environment to be on the safe side.

Non-hardy species such as the climbing Clerodendrum must always be overwintered in a frost-free environment. A bright place with temperatures between 10 and 15°C is optimal for this. However, the climbing Clerodendrum can also be overwintered in warmer places. In short:

  • Japanese Clerodendrum only needs winter protection during the first 2 – 3 years
  • Chinese Clerodendrum freezes above ground
  • Ugandan clerodendrum and climbing clerodendrums should be overwintered at 10 – 15°C in a bright place
Farges harlequin glorybower tree in snow
While some Clerodendrum species are not hardy, the farges harlequin glorybower tree can survive milder winters [Photo: nnattalli/ Shutterstock.com].

Are Clerodendrums poisonous?

The fruits of the Clerodendrum are slightly poisonous. Nevertheless, you do not need to worry, because the fruits are anything but tasty. So it is unlikely that anybody would want to eat more than one bite. You can therefore add the plant to your garden or home with a clear conscience.

For those who have got a thing for a little exoticism, we have assembled ten exotic houseplants from distant lands for you here.

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