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The garden hibiscus (Hibiscus syriacus) or althea bush after its old name, is related to the Chinese rose, which is kept as a houseplant. The plant is native to most of Asia. Hibiscus syriacus is the only species from this plant family that is hardy enough to be planted here in the garden.

The plant is deciduous, and can grow to 2 to 3 meters high and 2 meters wide. There are also lower growing cultivars available and plants grafted onto a stem. After sunny summers, the large white, blue, purple, red or pink flowers appear from mid-August until sometimes in October. There are cultivars with single and double flowers. The single-flowered plants can generally tolerate a bit more frost.


The hibiscus likes to be in a somewhat sheltered, sunny spot, where it can take full advantage of the spring sun. The more (morning) sun it gets, the better the bud development will be later in the year. In rainy, cloudy summers, the flower buds may drop before they open. If the plant is exposed to bright afternoon sun, the flowers (and the leaves) can droop, turn yellow or even partially wither in warm summers. If it only happens once that the plant hangs limp, you can spray some extra on those hot days. Also shielding with aBeach umbrellasee productRimbou sail Lotus 260 cm. Limited edition Canvas (Umbrella)or covering with a sheet can sometimes help to prevent damage. The plant will grow less quickly in bright sun.

Hibiscus grows on almost any soil, as long as it is airy, well-drained and contains a lot of humus. However, the most ideal is a somewhat loamy soil. In any case, the humus content must be brought up to standard when planting. After (re)planting, it is possible that in the first spring the plant will only show its leaves late, or will hardly grow. In later years this will recover on its own, as soon as the root system has developed sufficiently. In winter, around young plants, the soil should be covered with a layer of leaves, straw or garden peat to protect the roots. With older plants, such a winter cover is no longer necessary to protect the roots. However, a layer of mulch is appreciated to keep the soil moist. The soil around the roots should never dry out completely.

The plant can suffer from potassium deficiency. Symptoms of this are yellow spots on the older leaves, later withering leaf margins and premature leaf drop. Fertilizing with a potassium-containing fertilizer or, for example, some digested chicken manure can then help to restore the nutritional status.


By cutting back all branches by half the first spring after planting, the plant will branch out bushy. In fact, the hibiscus does not need pruning. The plant develops naturally in a beautiful shape, ascending vase-shaped in most cultivars. Dead and damaged branches must be removed. The seed pods can remain after flowering.

If the shrub becomes too wide or has otherwise become out of shape, it can be pruned. Prune preferably in March. The hibiscus flowers on annual wood, so on the young branches that have developed in the same growing season. If the plant has just become too wide or too high, the young branches, the part that grew the previous year, can be cut off. If it really needs to be rejuvenated, the main branches can be sawn off at approximately 50 cm from the ground. He will then walk out from below again. You can also choose to spread this over two years, so as not to be immediately confronted with a bare spot in the garden, and to be assured of flowering in the coming season.

In severe frost, the plants can freeze. As soon as the plant sprouts again in the spring, the dead parts can be cut away. Because the plants are often grafted onto a rootstock of the archetype H. syriacus, branches with differently colored, blue flowers can suddenly develop. Because the rootstock is stronger than the graft branches, those deviating branches should be cut away at the base as soon as possible.


The shrub often self-seeds, and the small plants can be grown further. The hibiscus can also be propagated by root cuttings. Buds are present on the roots, from which new shoots can develop. In the autumn, a piece of the root is cut off. The obliquely cut cutting has a length of approximately 5 cm. The soil is rinsed off, after which the cutting is placed with 1 eye above the ground in a mixture of peat dust. Using cutting powder promotes rooting and prevents the development of fungi. After the cuttings have been in a shaded place for a few weeks and kept moist, the first roots and buds have developed and they can be potted or planted.


Sooty Dew on Hibiscus
A hibiscus that is in a draft or on the wind can become susceptible to lice visits. The black spots on the leaves of the hibiscus are the ultimate result of an infestation by aphids (scale, woolly scale, common scale or another type of lice) in the spring. The aphids secrete honeydew and make small holes in the leaves or young stems through their sucking activities. The sticky honeydew is then an attractive breeding ground for fungi, such as sooty mold. This fungus forms the black deposit on the leaf.
Sooty mold is difficult to remove, but can be combated with a fungicide. However, it is better to tackle the problem at the root, and what to do about the lice. An early lice infestation can often be reasonably controlled by wiping the lice from the leaves and then rubbing them finely, or by spraying the lice from the plants with a strong jet of water. After the second half of July, the pest usually disappears on its own. If the aforementioned method does not help enough, the lice can be combated by spraying with a mixture of soap suds and methylated spirits (10 liters of water, 200 grams of green soap, 1/3 liters of methylated spirits). In case of strong infestation you can spray against aphids with, for example, Admire or Pyrethrum liquid. The treatment will then have to be repeated several times between the beginning of May and the end of June.
It is also possible that the honeydew does not come from aphids that are on the bush itself, but is caused by aphids that are in an adjacent tree, where the honeydew drips out. In that case, the lice cannot always be effectively controlled and, although it is more like treating the symptoms, it is possible to try to do something about the sooty mold. For example, you can spray with Vital from ECOstyle (based on fatty acids and plant extracts), Baycor fungicide (active ingredient bitertanol) or Rosacur Spray (active ingredient tebuconazole, or comparable agents.


Hibiscus Admiral Dewey double, white 2.00 x 1.50 m
Hibiscus Ardennes double, lilac 2.50 x 2.00 m
single, blue with dark heart 2.00 x 2.00 m
Hibiscus Boule de Feu double, dark pink-red 1.50 x 1.50 m
Hibiscus coelestis single, blue with red heart 2.00 x 1.50 m
Hibiscus Couruleus Plenus double, lilac 2.00 x 1.50 m
Hibiscus Diana single, white 2.00 x 1.50 m
Hibiscus Duc de Brabant double, dark pink to purple 2.00 x 1.50 m
Hibiscus Hamabo single, light pink with red heart 2.00 x 1.50 m
Hibiscus Helene single, white with pink red heart 1.50 x 1.50 m
Hibiscus Joan of Arc double, white 2.00 x 1.50 m
Hibiscus Lady Stanley double, white with pink red heart 2.00 x 1.50 m
Hibiscus Leopoldii double, white or light pink with red heart 2.00 x 1.50 m
Hibiscus Marina single, purple blue 2.00 x 1.50 m
Hibiscus Mathilde single, white with red heart 2.00 x 1.50 m
Hibiscus Mauve Queen single, mauve or soft red 2.00 x 1.50 m
Hibiscus Meehanii single, leaf white edged 1.50 x 1.50 m
Hibiscus Minerva single, light lavender blue 1.50 x 1.50 m
Hibiscus monstrosus single, white with red spot 2.50 x 2.00 m
Hibiscus Pink Giant single, pink with dark red heart 2.50 x 2.00 m
Hibiscus Puniceus Plenus double, red 1.50 x 1.50 m
Hibiscus Purpureus Variegatus single, leaf margined yellow 2.00 x 1.50 m
Hibiscus Red Heart (Flogi) single, white with red heart 2.50 x 2.00 m
Hibiscus Roseus Plenus filled, purple-red 2.00 x 1.50 m
Hibiscus Rubis single, purple pink 1.20 x 1.20 m
Hibiscus Russian Violet single, lilac red 2.50 x 2.00 m
Hibiscus Speciosus single, white with dark red heart 2.50 x 2.00 m
Hibiscus Totus Albus single, all white 2.50 x 2.00 m
Hibiscus Variegatus double, leaf yellow edged dark red 2.00 x 1.50 m
Hibiscus Violet Clair Double double, lilac with red heart 2.50 x 2.00 m
Hibiscus White Chiffon single, all white 3.00 x 2.00 m
Hibiscus William R. Smith single, white 2.50 x 2.00 m
Hibiscus Woodbridge single, dark pink 3.00 x 2.00 m

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