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 the 6 most important methods to increase the number of hibiscus flowers and ensure the blooms last for as long as possible…
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 the overall health of the hibiscus.
It is not common for garden soils to be naturally high in phosphorous to the point a hibiscus would be notably affected.
However high levels of phosphorous can occur because of the use of ‘bloom booster’ fertilizers which are ironically counter productive in the case of flowering hibiscus as the excess phosphorous makes it more difficult for the hibiscus to draw up other nutrients.
Note that tomato feeds also contain a higher proportion of phosphorous then 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, 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 prevent blooms. (Hibiscus do need some phosphorus, but do 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 then 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, how to revive a dying hibiscus for the solution.
2. Prune Hibiscus in the Early Spring For More Flowers
Hibiscus bloom 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 hibiscus respond well to a 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 the display more flowers.
Ideally there should be several nodes 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 a light pruning in early Spring.
3. Consistently Moist Soil Promotes More Hibiscus Blooms
Hibiscus flowers much more readily and for much longer when the are grown in consistently moist soil.
Some established hibiscus plants 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 falling off and to increase the display of flowers, 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 good options for mulch which should not only conserve moisture but also 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.
Water the hibiscus generously, ideally before any drought is forecast 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 for how to save the hibiscus.
4. Avoid Nitrogen Fertilizer to Promote More Flowers
A hibiscus plat 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 boarders and affect plants such as hibiscus, by reducing flowering.
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 then liquid fertilizers.
5. Hibiscus Flower More in Full Sun
The most important factor for increasing the amount of hibiscus flowers is to ensure that the hibiscus is located in full sun.
Whilst 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 day time temperature range of 65°F-75°F which is the optimal day time 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.
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 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 which 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 it shows signs of drought stress (wilting leaves and buds not opening).
6. Increase the Number of Blooms On Potted Hibiscus
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.
Plant the hibiscus in as large a pot as is practical.
Larger pots have a greater capacity for potting soil and therefore a greater capacity to hold moisture and a high availability of more nutrients which create the optimal conditions of the hibiscus to bloom.
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, use a fertilizer diligently in the Spring and Summer for potted hibiscus as potted plant have less access to nutrients then 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 to increase the longevity of flowers on a hibiscus is to plant the hibiscus in full sun. More sun give 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 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 to increase the number of hibiscus flowers. Pruning later in the season, delays flowering and can reduce the number of blooms.