Although it is tempting to plant a Tropical Hibiscus in our area (Northern and upper Central California) it is not advisable, due to winter cold i.e. freeze and cold snaps. Even the mildest freeze will damage Tropical Hibiscus. I have even had a hard time in Los Angeles area getting them established- between the mild winter cold and heat of summer its been hard. They certainly need their water to become established. Once established in LA they are fairly tough.
Certainly, there are exceptions but for the most part these plants are often better treated as annual potted plants rather than set out into the garden. We will see if global warming changes these comments but for now you may want to try a hardier Hibiscus called “Rose of Sharon” or Hibiscus syriacus.
The difference being that Hibiscus syriacus is a deciduous shrub so it can live through the winter as a dormant plant rather than suffering through winter with an abundance of tender leaves.
There are some beautiful hybrids of this plant with varied sized flowers and colors. They also fairly low water once established. Rose of Sharon is a large plant usually 6-8′ tall and can be purchased as a single trunked small tree or as a multi trunked large shrub.
They have a bit of yellow fall color and lovely small leaves.
Plant in full sun and in a spot with good air circulation. Water well at first to avoid wilting then taper off water to once or twice a week. Trim only for shape and do not shear, instead selectively prune away foliage that is diseased, dead or in need of clipping. Protect with shade cloth if they are wilting a lot at first.
Pictured below are Hibiscus syriacus ‘Minerva’, ‘Diana’, and ‘Red Heart’ (in order shown)
I would buy them at a local nursery rather than through mail order so that they are acclimated to your climate zone. Trim back in winter by 1/2 to keep the foliage full and to get lots of flowers. Fertilize twice in the summer with a balanced N-P-K fertilizer (nitrogen, phosphorus and potassium- shown on package) for flowering shrubs. They may need Iron if they are yellowing a lot in the summer. Use chelated Iron- easily dissolvable Iron and water in well. This works well for Citrus and Gardenias too.
