If you want your hibiscus to look its best in summer, prune it in late winter or early spring. Photo: aliexpress.com & lowes.com
If you’ve been growing a Chinese hibiscus (Hibiscus rosa-sinensis) indoors over the winter, it’s time to give it a good pruning. Cutting it back in late February or March (in the Northern Hemisphere) will stimulate it to produce extra branches and more flowers for the summer as well as keeping its exuberant growth under control.
The awkward part of pruning in late winter is that, under the influence of lengthening days, the plant is often already coming into bud … on long, ungainly branches. So, either you sacrifice the first few blooms of the season in view of creating a denser, more attractive plant that will bloom more heavily right through the summer, or you let your plant reach for the sky and bloom lightly on a less attractive plant. Your choice!

You can give your hibiscus a light pruning, cutting all branches back by about one third if you want to maintain it at about its current size, or a harsh one, cutting them all back to 2 or 3 nodes above the soil level if it’s become overgrown and needs to be kept in check. Also remove any dead wood or weak growth.
The general rule is to make the cut 1/4 inch (5 mm) above an outward-pointing node. However, if your plant is a bit unequal, you could cut back just above a node pointing in the direction of an open space in the plant. That will help it fill in.
Do note that you can use the trimmings as cuttings. You’ll need rooting hormone, as it’s a woody plant, reluctant to produce roots on its own. Root the cuttings in potting moist mix and cover with a clear plastic bag or dome, placing them in a warm spot. When you see new growth appear, the cutting has rooted and the covering can be removed.
Basic Care
Give your hibiscus full sun or at least as much light as you can and water thoroughly as soon as the soil is dry to the touch. Start fertilizing regularly after you prune it. Many people find applying a soluble fertilizer (any fertilizer will do) at ¼ the usually recommenced monthly does each time you water helps produce dense green growth and abundant bloom. Keep this up from late winter until fall, then give the plant a winter fertilizer break. And keep the atmospheric humidity up as well as you can: hibiscus plants hate dry air!
Early spring is also an ideal time to repot into a larger pot any hibiscus that is drying out too quickly between waterings. A larger pot will give the plant more space for its roots… and access to more moisture, stored in the spaces between the soil particles after you water.
A bit of a trim and some TLC just as spring is about to point will guarantee your hibiscus will be in top shape for its summer-blooming period!
When is the best time to cut back hibiscus outdoors
Outdoor hibiscus can mean many different kinds of plant, including perennials, shrubs, annuals, biennials, etc. Assuming though that you live in a temperate climate and that the hibiscus is a hardy one (it survives the winter outdoors), the best times would be late fall or early spring.
This is the post I needed.
This is one of my least favorites ‘shrubs’ in the Los Angeles region. They are less popular here because the foliage can get damaged by even mild frost. The so-called ‘gardeners’ shear them so regularly that they never get an opportunity to bloom. Their foliage is always tattered from the shearing. There are so many other species that work better for plain ‘shrubs’. Seriously, for a ‘shrub’ that will get shorn regularly, common Japanese boxwood would work better. The only hibiscus that get to bloom nicely are out of reach of so-called ‘gardeners’. On rare occasion, I see one blooming nicely in a garden that is not ‘maintained’ by a ‘gardener’. They have so much potential if pruned and groomed properly, or if allowed to grow wild with only minor grooming. Some types do not get too big and lanky.