I love hibiscus due to the number of flowers it produces that last for many months. To me, it is one of the highlights of Summer. I have had many years of experimenting with different methods for increasing how many flowers my hibiscus plants display.
In this post, I distill all the tips and hacks that I have found that actually work in terms of increasing the number of blooms every year…
To increase the amount of hibiscus flowers, ensure the hibiscus is planted in full sun and water generously in the Spring whilst the flower buds are developing. Hibiscus displays its flowers on new growth, so always prune hibiscus in early spring which stimulates new growth, and results in the hibiscus displaying more blooms.
Keep reading to learn my 6 most important methods to increase the number of hibiscus flowers and ensure the blooms last for as long as possible…
Table of Contents
1. Use The Correct Fertilizer For More Flowers (Avoid ‘Blooms Boosters’)
Hibiscus are fairly unusual plants in that they are particularly sensitive to high levels of phosphorous in the soil, which can not only prevent the hibiscus from blooming but also adversely affect its overall health.
It is not common for garden soils to be naturally high in phosphorous to the point a hibiscus would be notably affected. (This is not been a problem I have ever encountered)
However, high levels of phosphorous can occur because of the use of ‘bloom booster’ fertilizers, which are ironically counterproductive in the case of flowering hibiscus as the excess phosphorous makes it more difficult for the hibiscus to draw up other nutrients. (In my experience, many people make this mistake with their hibiscus plants).
I must emphasize that tomato feeds also contain a higher proportion of phosphorous than normal fertilizer to promote the development of fruit, so avoid using these types of fertilizer anywhere near your hibiscus plants.
To increase the number of hibiscus flowers and to make the blooms last a long time, I use a well balanced fertilizer with equal parts NPK (Nitrogen, Phosphorus and Potassium).
If the fertilizer is evenly balanced then the phosphorous content is not a problem in terms of preventing blooms. (Hibiscus does need some phosphorus, but does not tolerate high concentrations of the nutrient).
A fertilizer such as a miracle-gro all-purpose fertilizer contains all the nutrients the hibiscus needs at the right concentration to support flowering.
I personally prefer a granular fertilizer (rather than liquid fertilizers) as they release the nutrients slowly over the course of the peak flowering season to support the blooms for longer, whereas liquid fertilizers are water soluble and can wash away in heavy rain.
High levels of phosphorous in the soil can be a reason for the hibiscus leaves turning yellow and the hibiscus dying. If your hibiscus looks unwell, read my article on how to revive a dying hibiscus for the solution.
2. Prune Your Hibiscus in the Early Spring For More Flowers
Hibiscus blooms on new growth, so the key to promoting flowers is to prune the hibiscus lightly in the early Spring (March or April) as this helps to stimulate new growth from which the flowers are displayed ready for the peak.
If you prune too late in the season (in late Spring or Summer), then this can delay flowering for several weeks, which can result in the peak of flowering (which should be in Summer) occurring too close to Fall or Winter. The cooler temperature in Fall can cause the flower buds to drop before opening.
To increase flowering, my hibiscus responds well to light pruning, removing any leggy growth and maintaining a desirable shape. Prune any growth about an inch above a node to encourage new growth which can display more flowers.
Ideally, several nodes should be left on a branch, which can all produce new growth and, therefore, more flowers.
You can prune hibiscus in late Summer or the Fall, but this does not stimulate the new growth from which flowers are displayed to the same extent as light pruning in early Spring, which is why I always recommend that you prune in the Spring.
3. Consistently Moist Soil Promotes More Hibiscus Blooms
Hibiscus flowers much more readily and for much longer when they are grown in consistently moist soil.
Some established hibiscus plants in my garden rarely need any additional water due to their extensive roots, but for smaller hibiscus, newly planted hibiscus, or potted hibiscus, it is best practice to ensure that the soil is evenly moist, particularly in the Spring.
Early Spring is when the hibiscus flower buds are developing, and if the soil dries out at this time then sometimes the buds drop off or fail to open due to drought stress.
To prevent the buds from falling off and to increase the display of flowers, I water the hibiscus generously at the start of Spring and apply a 1-inch layer of mulch around the base of your hibiscus, which helps to keep the soil moist and prevents the sun from baking the soil dry and evaporating the soil’s moisture from around the hibiscus’s root system.
A layer of compost and leaf mold manure are my favorite options for mulch, which should conserve moisture, provide additional nutrients to the hibiscus, and stimulate the soil ecology.
Mulch also helps to keep the hibiscus roots cool at the height of Summer, which creates the optimal conditions for displaying the greatest number of flowers.
Useful tip: Water the hibiscus generously, ideally before any drought is forecasted, to increase the longevity of the flowers.
Drought stress is one reason why hibiscus leaves turn yellow. Read my article, why are my hibiscus leaves turning yellow? to learn the other reasons and how to save the hibiscus.
4. Avoid Nitrogen Fertilizer to Promote More Flowers
In my experience, a hibiscus plant with lots of lush foliage but few flowers usually indicates a high level of nitrogen in the soil, as nitrogen promotes growth at the expense of flowers.
Excess nitrogen usually comes from run off of lawn fertilizer (which is particularly high in nitrogen), using a liquid fertilizer too frequently, or due to amending the garden with manure (chicken manure, in particular, is high in nitrogen).
Lawn fertilizers readily dissolve in rainfall and can run off from the lawn into garden borders and affect plants, such as hibiscus, by reducing flowering.
I would avoid using manure as a mulch around your hibiscus (compost and leaf mold are better), be mindful of the use of lawn fertilizer, and preferentially use a granular fertilizer to support your blooms rather than liquid fertilizers.
5. Hibiscus Flower More in Full Sun
The most important factor for increasing the number of hibiscus flowers is to ensure that the hibiscus is in full sun.
While hibiscus can flower in partial shade or filtered light, both hibiscus species (Hibiscus rosa-sinensis) and (Hibiscus spp.) flower more abundantly in full sun.
More sun can also help to maintain the preferred daytime temperature range of 65°F-75°F, which is the optimal daytime temperature for the development of buds.
Cut back any trees or shrubs that cast shade on your hibiscus, or, if necessary, transplant your hibiscus in the early spring or fall to a sunnier location.
Transplanting in the Spring or Fall gives the hibiscus a chance to establish and uptake water without having to contend with intense summer heat.
Important tip: However, I should highlight that in particularly hot climates, the hibiscus often flowers better with 6 hours of morning sun followed by afternoon shade.
This is because the hibiscus can benefit from the sun in the morning, which is a much cooler time of day.
If the hibiscus is in the sun during the afternoon with blazing sunshine and scorching heat, this can stress the hibiscus by increasing evaporation from the soil and transpiration for the leaves, which can result in drought stress and the flower buds not opening.
In this case, water your hibiscus regularly and ensure it has a layer of mulch around the base to conserve moisture.
If your climate is really hot, consider growing hibiscus in pots so you can move them out of the sun, if necessary, if they show signs of drought stress (wilting leaves and buds not opening).
6. How I Increase the Number of Blooms On Potted Hibiscus
My potted hibiscus can flower as well as any other hibiscus, but there are a few best practices to be aware of to increase the number of flowers.
I encourage you to plant the hibiscus in as large a pot as is practical, as this has always given me the best results.
This is because larger pots have a greater capacity for potting soil and, therefore, a greater capacity to hold moisture and a higher availability of nutrients, which creates the optimal conditions for your hibiscus to bloom.
From what I’ve seen in smaller pots, hibiscus roots can become pot-bound and suffer drought stress or exhaust the soil of available nutrients.
The great thing about growing hibiscus in pots is that you can easily move the pot to an area with more sunlight, which is the most important factor for increasing the number of hibiscus blooms.
To ensure a good display of flowers, I use a fertilizer diligently in the Spring and Summer for potted hibiscus, as potted plants have less access to nutrients than a hibiscus planted in garden soil (miracle-gro all-purpose granular fertilizer is a great choice).
If your hibiscus is not flowering and you cannot work out why, read my article why is my hibiscus not blooming? for the answer.
Key Takeaways:
- The most important factor for increasing the number of blooms and increasing the longevity of flowers on hibiscus is to plant the hibiscus in full sun. More sun gives the hibiscus more energy to promote flowering.
- To increase the number of hibiscus flowers, ensure the soil is consistently moist in the Spring whilst the flower buds develop. Water generously and mulch the soil to promote the development of flower buds and maintain a display of hibiscus blooms for much longer.
- Hibiscus only flowers from new growth, so prune the hibiscus in early Spring to stimulate more growth and increase the number of hibiscus flowers. Pruning later in the season delays flowering and can reduce the number of blooms.
