The reason for hibiscus not flowering is usually because of too much shade, drought stress, or too much fertilizer. Too much nitrogen promotes leaf growth at the expense of flowers, and too little phosphorous decreases hibiscus flowering by immobilizing nutrients in the soil.
Drought stress or slowing draining soils can prevent hibiscus from flowering. To display flowers, hibiscus needs well-drained soil that is consistently moist. Unhealthy plants can be more susceptible to disease and pests.
Pruning at the wrong time can prevent flowering as hibiscus flowers on new growth. Avoid pruning in the Summer or Spring. Autumn is the best time to prune hibiscus in order to encourage flowering.
Too Much Shade Prevents a Hibiscus From Blooming
The most important thing for hibiscus flowers is how much sun they get each day.
Hibiscus flowers are at their best when in full sunlight with many fragrant flowers.
The less energy your hibiscus has to display flowers in summer, the better.
Hibiscus flowers in the tropical and subtropical climates of Asia, where they thrive in full sun and warm temperatures.
Always locate your hibiscus in an area with 6 or more hours of the sun, whether they are a variety of the tropical species of hibiscus or the hardier species of hibiscus. Both require full sun to flower, but the harder hibiscus species can tolerate cooler temperatures.
If your hibiscus grows in shaded areas in your garden or indoors, it is not meeting its needs. This can cause stress and stop the plant from flowering.
If possible, cut any shade-producing vegetation or move your potted hibiscus to a sunny spot.
Only tropical varieties can be grown indoors. However, hibiscus plants are not the best houseplants. To encourage blooms, ensure your hibiscus is placed in the sunniest window.
Too Much Phosphorous can Prevent Hibiscus Flowering
Although phosphorous is often used as a key ingredient in fertilizers that boost bloom, it can be detrimental to hibiscus flowers. This is because the hibiscus is sensitive to excess phosphorous.
An accumulation of phosphorous in the soil prevents the hibiscus root from taking other essential nutrients, which can cause the hibiscus to stop flowering or even kill it.
Avoid fertilizers that are not balanced. A well-balanced fertilizer has an equal ratio of Potassium, Potassium, and Nitrogen NPK. Prioritize improving soil fertility with organic mulches, such as well-rotted horse manure.
Hibiscus has a unique sensitivity to phosphorous. This can cause the flowers to not emerge for gardeners.
Too Much Nitrogen Affects Hibiscus Blooming
Hibiscus can be sensitive to excess phosphorous or even nitrogen if you apply fertilizer in too high a concentration.
Too much nitrogen causes your hibiscus to grow foliage at the expense of blooms, so it’s important to moderate your applications.
Too much fertilizer can make the hibiscus more susceptible to pests like aphids, which feed on sap and produce flower buds that can fall if it is infested.
Hibiscus can be heavy feeders, but they are best fed with mulch (compost, leaf mold, or well-rotted manure). You could also use a half-strength general liquid fertilizer, such as Miracle-Gro, once per month in the spring and summer.
This is often a good way to give the hibiscus the nutrients it needs to bloom without overindulging it and causing it to stop flowering.
If your hibiscus isn’t producing flowers but has lots of leaves, reduce the amount of fertilizer you use and continue to water it.
It may not flower this year, but if you fertilize the hibiscus more carefully, it should.
Wrong Time of Year For Pruning Affects Hibiscus Flowers
Hibiscus flowers on new years growth, so pruning in the growing season can have a serious impact on blooms.
A heavy pruning done in the Spring can cause the hibiscus not to flower in the Summer or delay its flowering.
Flowers that are delayed in flowering will often emerge in cooler temperatures in Fall than in Summer. They also tend to wilt faster.
Hibiscus flowers respond better to light pruning at the end of their growing season after they have finished flowering in September/October. This allows for new growth in Spring.
The Boggy Ground Prevents Hibiscus Blooming
Whilst hibiscus requires consistently moist soil, it should also be well draining.
If the soil is clay or compacted and water pools around roots, it may suffer stress. This can lead to hibiscus not flowering and can promote fungal diseases like root rot. Your hibiscus can die back.
If the soil is too damp or appears boggy, reduce the amount of watering. This will allow the soil to dry out around the roots.
Hibiscus can be brittle in soils like clay and saturated soils, so it’s best to transplant it into a well-draining area or a small pot.
For boggy, low-lying gardens, I recommend that you grow your hibiscus indoors. You can modify the soil profile to make it suitable for growing and flowering.
Climate Can Affect Hibiscus Flowering
Hibiscus is a tropical plant that thrives in warm, sunny, and humid climates in Asia.
Tropical hibiscus requires warmer, more humid conditions typically and does not tolerate freezing temperatures (hardy in USDA Zones 9-11).
The hardy species can tolerate a wider temperature range and generally flowers for longer the tropical hibiscus, although this can depend on the specific variety.
Tropical species can be more difficult to care for than their normal climates. They are less likely to flower if they are stressed.
Hardy species are more likely to bloom in warmer climates.
If your hibiscus is not blooming, check the species and plant the correct hibiscus for the climate.
Drought and Soil Can Prevent Hibiscus Flowering
If your hibiscus is not flowering, then this can be because it is stressed due to drought.
The most common cause of drought stress is under watering. Although established hibiscus plants may not need as much watering, potted shrubs of hibiscus should still be watered regularly to maintain plant health and blooming in the summer.
Sandy soil can does not retain enough moisture. Sandy soil can cause drought stress by draining too quickly for your roots to take up water.
To increase the soil’s ability to retain moisture, provide your hibiscus with an extensive soak using a hose. Then apply mulch to the soil around the hibiscus.
Materials like compost, leaf mold, and well-rotted manure make excellent mulches for your hibiscus. They retain moisture, add nutrients, and maintain the soil’s pH to suit your plant.
Mulch also improves soil structure, so add a layer to your hibiscus plants before the beginning of spring.
The frequency at which you water depends on the climate and weather conditions. However, if you regularly test your soil for moisture to about a finger depth, you can establish how fast your soil dries.
Give your hibiscus a good soaking as soon as it is dry to ensure that they are healthy and will bloom in the Summer.
Pot Conditions can Affect Hibiscus Blooming
The same reasons why hibiscus does not flower also apply to potted hibiscus, but there are some conditions that can cause your hibiscus to not flower.
If your potted Hibiscus plants are not blooming, it can be:
- The hibiscus has been in the same pot for many years and exhausted the available nutrients. Pots are limited in soil capacity and have fewer nutrients. Potting soil can become compacted and require frequent watering to remove water-soluble nutrients.
- Small pots dry out too quickly. To flower, hibiscus needs full sun, warm temperatures, and moist soil. Pots that are smaller retain less water and heat up faster in the soil, which can cause drought stress and increase evaporation. This will also prevent hibiscus flowers from blooming.
- Pots without drainage holes in the base. The best hibiscus plants require well-draining soil. If they are placed in decorative pots that do not have drainage holes in the base, water can pool around the roots, which can cause root rot and prevent flowering.
- In smaller pots, the roots can become pot bound and even cause a blockage for the drainage holes of the pot, which causes slower drainage, boggy soil, and increases the risk of diseases.
If your hibiscus plants have been in the same soil for a long time, you may need to report them to ensure plant health and flowering.
Repot with high-quality multipurpose compost to improve soil structure and moisture retention.
Repot the hibiscus into a larger container so that the roots can establish themselves and get the nutrients and moisture they need to flower.
To ensure drainage, make sure the container or pot has drainage holes and add a 1-inch layer of gravel to the bottom.
Buds Falling Off Prevent Hibiscus From Flowering
If they are infected, hibiscus flowers are generally resistant to diseases and pests. However, if the hibiscus suffers from stress, it can lead to infestations that may cause the flower buds to fall or not to open properly.
These stress-related causes include water stress due to drought or boggy soil, too much fertilizer, and nutrient-poor soil.
Too much nitrogen from fertilizer can cause softening of the foliage, which attracts insects like mealy bugs, spider mites, and thrips.
Inspect the leaves for signs of insect pest infestations. You can use an insecticide to get rid of them.
Although your hibiscus might not be able to recover in time for flowering this year, getting rid of pests will keep it healthy and should allow it to bloom the next year.