Dombeya is a large genus of flowering shrubs with about 200 recognized species. Dombeya, also known as the tropical hydrangea or the pink ball tree, is native to India, East Africa, and Madagascar.
In addition to the named species, there are also several dombeya hybrids.
The dombeya can be grown as a shrub or a tree, growing in both height and width to about 25 feet (7.62 m).
History
The dombeya shrub has grown as an ornamental plant since the 19th century. Although it appears on the compendium of invasive species in Cuba, it seems that it is not commonly grown on the island.
Dombeya is reputed to have arrived in Europe from India, but little information exists as to the detail of its spread outside its native regions. Dombeya is a pretty plant when cultivated, however, it is not a common garden species.
Plant Facts
| Scientific name | Dombeya |
| Common names | Tropical hydrangea, pink ball tree, pink wild pear flower |
| Genus | Dombeya |
| Family | Malvaceae (formerly Sterculiaceae) |
| Height | Up to 25 feet (7.62 m) |
| Width | Up to 25 feet (7.62 m) |
| USDA Plant Hardiness Zone | Zones 9 to 11 |
| Native to | India, Africa, Madagascar |
| Blooming season | Spring |
| Flower colors | Pink, white |
| Plant specific features | Semi-evergreen, spectacular blooms |
How to Plant and Grow a Dombeya Bush
Once you have chosen your planting site, prepare the soil well to obtain a good soft, well-mixed growing medium for your dombeya. It may be necessary to add some sand to the soil, to improve the drainage.
When planting a container-grown dombeya, dig a hole a little larger than the container in which it is growing.
Water well before removing the shrub from its pot, in order to remove the roots easily and minimize damage.
Add a little sand and some soft compost at the bottom of the planting hole. This will help the dombeya roots to establish themselves in their new growing environment.
Place the shrub in the hole, making sure it is straight and upright. Then backfill around the plant using well-worked compost.
Water well, and tamp down around the base of the plant. This will ensure that you don’t damage the stem or any surface roots when compacting the soil.
Where to Plant
Due to its intolerance to salinity, do not plant dombeya in a coastal location. It will not survive if it is exposed to salt spray or salinity in the soil.
It is a tropical or subtropical plant and needs protection from frost. Plant either in a container where it can be moved when temperatures fall or in a well-sheltered position.
Despite its tenderness, it has drought tolerance once mature. Dombeya grows in a wide range of soil types and also in both sun and partial shade. This makes it a versatile addition – if you have the climate.
When deciding where to plant the shrub, It is also important to consider the potential size of a mature dombeya, as it will grow very tall if unchecked.
Dombeya shrubs are very beautiful and provide a long season of interest. If you decide to grow multiple dombeya plants, then space them at least 3 feet (0.91 meters) apart to give them room to grow – they are fast-growing shrubs.
When to Plant
If sowing seeds or planting a container-grown dombeya, the best time to plant is in the Spring. In Europe, the dombeya shrub flowers between April and June.
Dombeya shrubs are not native to North America but are hardy between USDA zones 9 and 11. If growing in one of these zones, you can plant the shrub at any time of the year.
Dombeya Shrubs Care and Maintenance
Soil
The dombeya grows in many soil types, from dry and sandy, to clay and sometimes wet soil. However, it does need to be well-draining and ideally have a neutral pH value. The dombeya will tolerate soil that is mildly acidic and mildly alkaline.
If planted in soil that is alkaline, with a pH value >8, then the dombeya will suffer from nutrient deficiency. This can be treated by applying an appropriate fertilizer regularly.
The tropical hydrangea or pink ball tree does not tolerate salinity, either in the soil or as sea spray in the air.
Water
Once mature, the dombeya is tolerant to drought and will survive hot, dry spells. However, the growth rate will be faster if the dombeya tree is watered, particularly during prolonged dry spells.
As a rule of thumb, water during the flowering period, when the soil is dry. You can water considerably less during the winter months.
Grown as a container plant, the pot-grown dombeya shrub will need weekly watering.
Fertilizer
Fertilizer applications should be carried out after pruning and this will increase flower production. A mulch applied at the base of the plant is also a good idea.
However, it is important that the mulch conserves water in the soil, but doesn’t come into contact with the stem or trunk of the plant itself.
Sunlight
Dombeya shrubs have beautiful flowers and this is an ideal plant to choose for a sunny environment. If planted in partial shade, it will survive, but flowering will be reduced.
Pruning and Repotting
Start by removing any dead, diseased, or decaying wood. This can be done at any time of the year, whenever you notice twigs and dead wood.
Removing dry, dead flowers is a good idea, to keep the neat appearance of the shrub or tree.
Some species drop their spent blooms before they turn brown. This will give you a beautiful rose-pink carpet of fading flowers around the base of the dombeya.
With most species of dombeya, the old flowers stay on the shrub for a long time.
Annual pruning will keep your plant’s growth in check, and retain the natural dense shape of the dombeya. After flowering, you can tidy up the shrub, removing any twiggy growth.
Propagating
Dombeya is most usually propagated by softwood stem cuttings, in the spring or early summer. Softwood cuttings should be taken from the plant’s current season’s growth before it turns woody.
The best time to take these cuttings is in the Spring when the plant is producing vigorous new growth.
Make the cuttings at least 4 inches (10.16 cm) long, and remove the lower leaves. This will aid with moisture conservation. Dip the tips of the stems into hormone rooting powder, as this will speed up the rooting process and give you a higher success rate.
Place the cuttings into a tray or pot filled with well-moistened potting compost. Cover the trays or pots with plastic to guard against the compost drying out. After about two weeks, you can remove the plastic cover.
It will probably take about six weeks for the cuttings to develop small roots. Keep the newly rooted cuttings in a sheltered place for the winter and plant out the following spring.
Cuttings are a quicker way to multiply dombeya shrubs, but it is also possible to sow seeds in the late Spring or Summer. Seed trays should be covered, and kept moist.
The dombeya seeds will take about 2 months to germinate. Once germinated, you can prick out the seedlings and plant them in individual pots, water when the compost is dry, and keep out of any risk of cold and especially frost.
And bear in mind, that a dombeya will probably not start to flower until it is at least 5 years old!
Pests and diseases
The most common insects to attack the dombeya shrub are aphids and scale insects. Following damage to the foliage by these pests, the plant may suffer from fungal diseases such as sooty mold.
From time to time, an increase in the number of nematodes and other insects in the soil can lead to root damage. These insects will reduce the size of the plant’s root system, resulting in a less healthy plant.
Generally, however, the dombeya is a relatively low-maintenance plant with few problems.
Temperature and Humidity
Dombeya is a plant that is rarely grown in private gardens. More usually, it is cultivated as a specimen shrub or tree in botanical gardens. It is often grown in containers, or placed in a sheltered position, as it needs to be protected from frost.
Although the dombeya is not a hardy plant, it will probably survive if exposed to short spells of cold temperatures occasionally. The shrub will probably suffer a little from exposure to the cold, and the leaves will turn yellow and drop.
However, once the warmer weather returns, the plant normally recovers well and will form new growth and leaves.
Dombeya shrubs are evergreen when grown in their native environment, and it is only if they are exposed to cooler temperatures that they will lose some or all of their leaves.
Once established, the tropical hydrangea is drought tolerant.
Other Uses for Dombeya shrubs
Some species of dombeya can be planted to grow as ornamental trees, whilst if pruned regularly to keep their dome shape and limited height they make ideal ornamental shrubs.
In the wild, in its native regions, some dombeya species are harvested by local people. The leaves and stem have a medicinal value, used to treat conditions such as glaucoma, and the roots for other, medical conditions.
The bark of the dombeya is very fibrous, and native people use it to make baskets. The wood itself is used for making the handles of hand tools and, of course, for firewood.
Types of Dombeya You Can Grow
As already stated, the Dombeya genus is huge! Identifying specific varieties is really a matter of choice, based on availability and personal requirements. However, there are some species that stand out as being “outstanding”.
Dombeya x seminole is a cultivar that is sometimes confused with Dombeya wallichii. The main difference is that the flower heads of the D. wallichii are suspended from the stems and are very fragrant.
D. x seminole flower heads are upright and have no scent. They have a very long flowering period and the bees love them! This is a fast-growing plant that needs pruning regularly to prevent it from becoming leggy. It doesn’t wilt if deprived of water, which is an added bonus.
Another magnificent variety is D. calantha which is a rare shrub and hard to source. But its flowers, which hang in clusters, are an absolute delight. The flowers provide a spectacular show and are long-lasting.
Conclusion
It is hard to imagine a more beautiful and impressive garden shrub or tree than the dombeya. Pink clusters of scented flowers that are equally showy as the blooms of a hydrangea lasting for several weeks, on a fast-growing evergreen.
What a pity, though, that the dombeya is a tropical plant, growing only in USDA zones 9 to 11!
*image by PantherMediaSeller/depositphotos
