I receive many questions about sick frangipani plants, such as why won't my flowers open, why are my leaves turning black and falling off. So I decided to summarise all the symptoms, possible causes and solutions. Hopefully your frangipani problem will be listed here!

 

Flowers

Flowers Not Opening

Generally, when a plant flowers, but then the flowers do not open, it is due to prevailing temperatures. This happens most often at the tail end of the flowering season in autumn. Although it may still seem quite warm during the day, if overnight temperatures are too low, the frangipani starts to prepare itself for the winter dormancy period. Those unopened flower buds will eventually drop off.

Frangipani Not Flowering

If your frangipani is otherwise healthy, but not producing flowers, there are 3 most likely causes. The first is that the branch or shoot is too young. When a frangipani is pruned, new branches generally take 2 years to flower. The same goes for a frangipani branch that is propagated after being cut away from the parent tree.

The next cause could be insufficient sunlight. At least 6 hours a day is best. A warm sunny position against a north (in the southern hemisphere or the opposite in the northern hemisphere) or west facing wall is best. Frangipanis in other positions will grow and produce leaves, but not necessarily flowers.

The third possible cause is likely to be insufficient fertiliser, or the wrong type of fertiliser. Most fertilisers contain nitrogen, potassium and phosphorous. It's the phosphorous component that promotes flower growth, so look for a fertiliser with high levels of phosphorous.

 

Leaves

Leaves Turning Black & Withering, Leaves Droop And/Or Drop Off

Drooping leaves usually mean too much or too little water. Have you had a lot of rain lately, or does the pot sit in a saucer that holds water? If so, then it may be too wet (and yes - frangipanis can be quite dramatic when complaining about too much water!). Alternately, has it been hot, humid and / or windy where you are? Terracotta pots in particular are very free draining, so your plant may just need some water.

Just to be on the safe side though - have a quick check at the underside of the leaves for pests & diseases. Check for orange spots (rust), black spots (mould or scale) or white spots (powdery mildew).

For mould – spray with white oil, and feed the plant with a fertiliser high in potassium or potash which will boost the plant's natural resistance to diseases.

For rust, remove the affected leaves and place these in a bag and put them in the bin. Don't compost them, and don't let the leaves fall onto the soil as this will just spread the fungus spores which cause the rust.

For scale, if there aren't too many, scrape them off with your fingernail and dab the spot with a bit of rubbing alcohol on a cotton ear-bud; if there are a lot, you can use white oil spray or an insecticide designed for scale, or, for a long term organic solution, try encouraging ladybugs to your garden by planting some daisies, zinnias or zucchini nearby.

Powdery mildew is generally caused by poor air circulation (or high humidity), and can be treated with white oil or a fungicide. If you prefer an organic solution, try mixing a little powdered milk with some detergent and a little water and spray that on the leaves.

Make sure whatever you use you spray late afternoon after the sun has gone off the leaves (to prevent scorching from the sun).

New Leaves Not Opening

This can quite often happen with a new cutting which has not had sufficient time to dry out before planting. If this is a new cutting, remove from the soil, and feel along the length of the cutting checking for soft spots (from the base of the cutting up). If the base of the cutting has started to rot, cut back to the first solid part of cutting, and then leave to dry out for 2 to 3 weeks before repotting.

If this is an established plant, see tips above for leaves dropping off.

Black/Brown Bumps On Leaves (Top Or Underside)

This is scale. If there aren't too many, scrape them off with your fingernail and dab the spot with a bit of rubbing alcohol on a cotton ear-bud; if there are a lot, you can use white oil spray or an insecticide designed for scale or for a long term organic solution, try encouraging ladybugs to your garden by planting some daisies, zinnias or zucchini nearby.

Top Of Leaves Looks White

This is powdery mildew which is generally caused by poor air circulation (or high humidity), and can be treated with white oil or a fungicide. If you prefer an organic solution, try mixing a little powdered milk with some detergent and a little water and spray that on the leaves. Make sure whatever you use you spray late afternoon after the sun has gone off the leaves (to prevent scorching from the sun).

Dry, Crinkly, Scorched Areas On Leaves

This is caused by watering (or rain) in the middle of the day followed by strong sunlight, which scorches the leaves. Although unsightly, this will not harm your frangipani.

Orange / Yellow / Brown Spots on Underside or Tops of Leaves

This is frangipani rust which is becoming more and more common. For rust, remove the affected leaves and place these in a bag and put them in the bin. Don't compost them, and don't let the leaves fall onto the soil as this will just spread the fungus spores which cause the rust.

 

Branches

New shoots drop off and discolouration of bark

Check for mould – this will show as white or black discolouration on the branches and/or leaves. You should treat the mould with a copper based fungicide and white oil.  Always spray late in the afternoon after the sun has gone off the plant (so you don't scald it). The mould itself will not harm your frangipani, but is very unsightly and can spread to other plants, so it is best to get rid of it ASAP.

If your branches are discoloured with orange, red (or any other colour), then check your soil and/or pot. Some old wine barrels, if not cleaned sufficiently, can leach chemicals into the soil (and therefore your plant). In this situation it is best to discard the soil and repot with new soil into a new container. If it is not too far gone the plant should recover.

Breaking or splitting branches

Frangipani branches rarely split of their own accord. However, if you have a lot of rain at the same time you have a lot of new leaf growth, the weight of the branches could cause them to split. If possible, try to stake up some of the heavier branches (support them from underneath). Once the weather has cooled, you may want to look at some judicious pruning if some branches seem to be too heavily laden.

If the branch has split or broken but it is still quite attached, it depends how deep the break goes. If there is a chance moisture could enter, you'd be better off to cut off the branch completely, leave it to dry for two weeks, then plant it to make a new frangipani. If the break is minor and on the side or underside, you may be able to save it by wrapping an old stocking around it and giving the branch some extra support until it heals over. Just keep an eye on the bark just above the break for any sign of withering - this is a sign that moisture is getting in. You may even be able to use the same method (a ladies' stocking) to support the branch from above if there is another suitable branch or some way you can stake this to the main trunk (say higher up).

Branch tips turn black

Plumeria Obtusa suffer from a disease called Black Tip Fungus which causes the new leaves to wither and drop off. It will eventually turn the tip of the branch black too. The best way to treat this is with lemon juice - just squeeze a lemon over the tip and give it a bit of a dab in. Black tip is usually caused by high humidity after a cold spell, and is rare in subtropical and tropical climates.

Plant is unstable

Frangipanis have fairly small root balls (for their size) and are not very deep feeders. Therefore planting a large cutting will require some staking until the roots take hold in the soil. The best way to stake a large frangipani cutting is with 2 to 3 stakes placed around the frangipani, and tied to the frangipani with old stockings (these won't harm the bark).

 

Propagation

Replanting broken branches

If a branch breaks off or splits away don't despair – just think of it as a new frangipani! Just clean up the break with secateurs or loppers. On the main trunk, make the cut to minimise any water being able to get into the wound. For the broken off piece, remove all leaves and flower spikes and leave it in a cool dry place for 2 - 3 weeks for the end to dry off, then you can place in a pot with some free draining potting mix.

Propagating from cuttings

Frangipanis grow very well from cuttings. Here's what you need to do: Make sure the edge where the cutting has been taken is a clean cut (if not, cut it again with some sharp secateurs). You need to leave the cutting to dry for a period of time. If it is summer / autumn where you are, remove any flower spikes and leave to dry in a cool dry spot for 2 - 3 weeks. If you are in winter / spring, chances are the branch is already bare, so just leave it for 3 to 4 days to heal over the wound in a cool dry spot. When the wound has healed, place it in a pot with free draining potting mix. Terracotta pots are great because they breathe. Make sure the pot is solid enough to support the weight of the frangipani. Also, frangipani are fairly shallow rooted, so don't place in a tall thin pot. You may need to stake up at first depending on the size of your cutting. Water it in once, then leave for 2 weeks (unless it is really hot where you are).

Getting your frangipani to seed

I am often asked whether there are male and female frangipani plants and do you need one of each to get seed pods. The answer is no - each frangipani flower contains both male and female parts within it. Frangipanis need a pollinator to produce seed. Their most common pollinator is the sphinx moth, which is fairly hard to come by. It is possible to self pollinate frangipani by hand using some fishing line (enter it into the throat of the flower and try some get some of the pollen onto the female parts). I suspect it's a bit hit and miss, although I have given it a try myself this summer – I guess I'll know next year how successful it is!

 

A happy frangipani doesn't ask for much – a sunny spot, a little water in summer, free draining soil, protection from winds and frost, and some fertiliser during the growing season.  And what a gift you get in return – a heavenly scent and beautiful flowers!