Hello, I’ve got 30 year old hibiscus plants. In recent years they appear to be very healthy (lot of green leaves) but rarely a flower. I rarely fertilize. They spend the summer months in the outdoors though protected from direct sunlight which would cause leaf burn. Other than not flowering the plants appear healthy with very green leaves. How can I get them to flower?
Perhaps I need to size up the pots?
Can the branches be pruned back now prior to bringing indoors for the winter months? If yes, how close do I cut to the centre branches?
Below you will find care instructions for Hibiscus plants – hopefully you will find these helpful and get your plants to bloom.
Re-potting: If plant roots protrude from drainage hole or when plant is lifted out of the pot, roots appear to be circling or tightly packed, then it’s time to re-pot. Upgrade to the next size up pot, do not go too big. Loosen roots and prune back some if necessary. Re-plant at the same level as it was originally, do not lower or raise the trunk in the new pot. Water well & mulch lightly.
Soil: Hibiscus like loamy, lightweight soil so a mix of 1 part garden loam, 1 part sand or bark and 1 part peat moss should be ideal.
Pruning: The best time to prune is in spring after the threat of frost has passed and as you are bringing the plants outside for the summer. Prune out any dead, diseased or damaged branches first, then prune for size & shape. Prune back to green wood and make your cuts 1/4 inch above leaf buds, cutting at a 45 degree angle. Hibiscus flowers are produced from terminal buds at the end of branches so cutting back to above bud nodes should encourage more terminal growth, hence more flowers. A maximum of 1/3 of the plant can be pruned out per year if you want to reduce the size and still maintain flowering. Pruning should be done using clean sharp implements in order to lessen the chance of disease spread and branch damage.
Watering: Warm water should always be used as cold water shocks the root system. Water with a temperature of around 30 degrees C should be perfect. Testing the moisture by inserting the top of your finger into the soil before watering will let you know when it needs a drink. Soil should be moist but never soggy. Water thoroughly and let excess drain off into a saucer which can be allowed to stand there for a maximum of 12 hours, then empty the saucer.
Fertilization: Actively growing plants need to be fertilized on a regular basis if they are to flower. Sprinkling a slow release 20-20-20 or 10-10-10 fertilizer on top of the soil a couple of times during it’s outdoor period should feed the plant well. Alternatively, a 1/2 strength soluble fertilizer can be used at watering time about twice per month. Ensure that whatever fertilizer you choose, it has iron & magnesium included as these will encourage flowering.
Light requirements: During winter when your hibiscus are indoors, place them in a sunny window location (ideally south facing) no closer than 2-3 inches from the glass – at night when the exterior temperatures drop, bring you plants slightly away from the glass to protect from the cold. In the summer, when you move them outside, place them in a location that gets at least 1-2 hours of direct sunlight daily. Exposing them to the outside and then into the direct sunlight should be done slowly over the course of a few weeks in order for them to acclimatize and not suffer leaf burn.