Hibiscus: Greenhouse Plants
W – warm, minimum of 13°C (55°F)/t
These are familiar plants to anybody who has been to warmer countries where they are a very popular garden plant. Those commonly seen abroad are Hibiscus rosa-sinensis or varieties of this and are the same as those cultivated in Britain in the greenhouse. There are many different varieties which produce the beautiful showy flowers in many colours and shades of white, pink, red, orange, yellow, cream and purple. H. r. ‘Cooperi’ is grown primarily for its variegated foliage. Whereas the others do well enough in a warm house this makes a much better plant in tropical temperatures. This is also true of H. schizopetalus from Kenya and tropical Africa. It has amazing flowers with recurving fringed red petals. It is best grown as a climber and trained up a wall or trellis where it will flower profusely. The only problem with growing Hibiscus in pots is that they eventually become leggy and unattractive. Should this happen prune them back hard after most of them have finished flowering in the autumn which will encourage them to grow into better plants. If temperatures have to be lower in winter keep old plants on the dry side and carry out the pruning in spring. This is also a good policy ifare required as they will root better from young material in spring than from old during winter.
In recent years F1 hybrid Hibiscus have been developed. H. ‘Southern Belle’ is the one that produces enormous dinner plate sized flowers of 25 cm (10 in) across. However, to get the best of this the seed must be sown early in February and grown on well which means never allowing it to become potbound, feeding and watering well. After flowering the plant can be pruned and kept for a following year. ‘Dixie Belle’ is another F1 hybrid which does not grow so tall and is an annual. All Hibiscus are prone to attack by whitefly.