Do you need green fingers for flowering Plumeria indoors? Well, everyone can have green fingers. The secret is in understanding your plants’ needs and giving them what they want. There are only two reasons why your potted friends are not thriving or even dying – either they are getting too little of something or too much of something. That something can only be water, nourishment, light or heat. You just need to find the right balance of those elements and your fingers will be glowing green as well as your plants.

Understanding and carrying for Plumeria

Nothing explains a plant’s needs better then looking at its natural environment. Evolution has adapted it during millions of years to the best possible way for those conditions. Moved out of habitat it will only thrive if provided with similar conditions.

Plumeria’s homeland is a vacation paradise – Caribbean islands and tropical coasts of Central America. Seasonal winter and summer changes there don’t mean warm and cold seasons or any considerable changes in day light length. Instead, it means wet and dry seasons and that is what Plumeria is made to deal with. The stem and branches are designed to store moisture during the months without rain. In addition, the tree will drop the foliage and stop growing also to conserve the water received during the rainy time of the year. It will go dormant ready to wake up as soon as the favorable conditions return. Normally, the tree will celebrate the new growing season with a firework of new inflos coming up on tips of most of the new branches even before new leaves develop.

Plumeria growing temperatures

Learning how to deal with cold temperatures was never on Plumeria’s todo-list. A dormant tree growing in ground can withstand brief periods, i.e. a couple of nights with temperatures dropping right above freezing point. Any lower temperatures will cause cold damages and longer periods will kill it. A potted plant should not be exposed to temperatures bellow 60F (16C) day or night. The rule of thumb here – if it is cold for you to be without a shirt outside, it will be cold for your Plumeria as well.

Look up your hardiness zone here or on this map. If you are lucky enough to live in zone 10b or 11 you can go ahead and plant Plumeria in the ground. For all of us living outside those tropical zones we will have to keep our precious warm and sun loving plants in pots and containers.

A warm, sunny, south facing window will be the best spot to put it. During the summer you can move it out to a patio or balcony. It will need all the sun it can get, unless it doesn’t mean an extreme heat. The most favorable light and temperature combination for Plumeria is 78-90 F (26-32 C) and the sun behind a very light veil or direct sun.

Make sure however that it doesn’t get too hot. Temperatures over 100 F (38 C) can cause burn damages on foliage and stem in direct sun. If you get this extreme heat, you should protect your Plumeria from direct sun.

Plumeria will also grow fine in a normal room temperature of 72-75F (22-24C), providing it receives at least 4-6 hours of direct sun light.

Right light for growing and flowering Plumeria

Living in Northern Europe I am well aware that here or in similar areas, during the winter, the sun light requirements above are impossible to meet with our very short, mostly cloudy winter days. Indoor growers, however, can benefit from the fact that most of Plumeria species are deciduous (except Plumeria obtusa and pudica). While the dormancy mechanism is actually developed for dry seasons we can use it for cold and dark seasons instead.

As the days are getting shorter in your location, your plant will notice it and slow down in producing new growth and eventually drop all the leaves and go hibernating. It can stay in this state for 3-5 months with just as little as one cup watering per month. During this time the best option is to move it to some kind of heated storage room. Just make sure it doesn’t stand on a cold concrete floor. No light will be needed.

When the sun and warm returns you should start watering it again to bring it back to life for another growing season.

Artificial light

Providing an artificial light during the dark period of the year might be an alternative to the winter storage. Even the deciduous varieties will keep most of its foliage and will continue to grow and flower throughout the year with an easy setup.

If you have just a couple of plants you don’t need professional growing lights. In fact, any reasonably bright light source will do just fine as long as it’s placed right above the growing tips. Your Plumeria will grow and flower under fluorescent tubes or energy saving bulbs, as well as under LED lamps. I’ve been using them all and can’t tell that there is a considerable difference in the results. The only thing I didn’t use is those expensive and energy consuming growing LED lights. Firstly, because I’m happy with my plants blooming with significantly cheaper appliances. Secondly, I wouldn’t stand the pink blueish light those growing lamps are producing.

Right now I’m using two different types of lamps: energy saving bulbs (CFL PAR38, 23W, 6000K), which can be fitted into a regular floor lamp high enough to place the bulb 10-12in (25-30 cm) above the growing tips; and LED bulbs (PAR38, 36W, 6000K) mounted from the ceiling.

6000K in the specifications above is a color temperature of the light, which the lamp is emitting. The color temperature of direct sunlight is about 5780K and an overcast daylight’s temperature is 6500K. Remember Plumeria’s favorite days are when the sun is behind a light veil. That would correspond to about 6000K.

Manufacturers insist that we consumers prefer the lamps with warmer, yellowish color temperature of about 2700-3000K in our living environment, while 5000-6000K is more cool white. That might be a matter of taste or habit for us humans. Personally, I prefer cool white light more resembling the daylight.

As for plants, the mainstream opinion is that they are more efficient in consuming cool white light in the range of 5000-6500K, rather than warm white light. Some sources are claiming that there is no big difference. From my own experience, without done much scientific(ish) research, I’m leaning toward the cool white. Also warm white would be clearly better, than no light at all.

If you keep your plants indoors, you will need to have the light on everyday for 12-14 hours. Try to be consistent and don’t change the number of hours you have the light on. For instance if your plants get used to 16 hours of light a day and you change it to 12 hours it will trigger the dormancy mechanism and stunt the new growth for some time or can even lead to foliage drop. An easy power timer can be a good solution.

Plumeria watering and feeding

While dormant Plumeria can survive months without water, it will require regular watering during the growing season. Hot weather and many leaves leads to faster evaporation and during the summer you may need to water it as often as every second day or even daily. However, Plumeria roots should never be standing in water. All the excess water must be drained directly. So when watering you should try to get used to give so much that only some water will come out from the pot into the pot tray. Remove the excess water if it feels up the tray.

The upper soil layer should get almost dry between waterings and my tips to you about having a sand layer on the top can help you to tell when it’s time. Dry sand easily movable around is a signal to get the watering can. This cheap and natural indicator works all seasons in any weather conditions.

Like all leaving things, plants needs to have not only water, but food as well. In their natural environment Plumeria will get all the required elements from the soil. Potted plants cannot do it on their own and relay on us providing the fertilizers.

I told you that the secret of green fingers is in getting to know your plants. It includes knowing what kind of food and in what proportions they need for growth and flowering.

If you read the info labels on the fertilizers’ packages you will find that the manufacturers always provide so called NPK-value for each fertilizer. We humans, require three macronutrients for surviving, which we get with our
food: protein, carbohydrates and fat. Plants need three macronutrients as well,
but those are nitrogen (N), phosphorus (P) and potassium (or kalium
in latin; K).

The NPK-value of fertilizer is there to tell the relative content of those elements stated with three numbers. Different plants have different “tastes” or nutritional requirements. Plumeria happens to be a great fan of phosphorus so you will have to give it a fertilizer with a big middle number in NPK-value, and they are big eaters too. You will have to feed it every third or fourth watering.

I’ve been using fertilizers with extreme high phosphorus value (NPK 10-50-10), but switched now to more balanced one with NPK 20-20-20. It is still high enough both for good growth and flowering, but it doesn’t destroy the soil as fast as the first one by depositing a lot of salts.

Humidity

Do you remember the feeling of stepping out of the plain when you arrive to a tropical country? It is like entering into a soft, warm and humid wall. It feels so humid because hot air can contain much more of water vapors comparing to cold air. Plumeria is engineered for those conditions. It is made to extract water not only with roots, but with leaves as well. A simple spray bottle can be a simple solution to mimic that tropical humidity.

Spray the leaves once or twice a day to keep them happy. A good idea is to incorporate it into your wakeup/bedtime routines. Mornings and evenings are also the time of the day when the leaves are most acceptable to the water.

For those into more technological solutions I would recommend an air humidifier. During winter time when it is freezing outside the air in our apartments normally is extremely dry. Keeping it more humid is beneficial not only for your plants, but also for your own respiratory system and even for your furniture.

Foliage feeding

Plants growing in pots do not have as large root system as the ground growing and have fewer possibilities to take up nutrition. Foliage feeding can compensate that. Once a week instead of regular morning or evening spraying you can use your spray bottle to apply the same fertilizer solution you use for roots, but only about 1/5 of that regular concentration.

Flowering Plumeria indoors

If you follow all the advises in the previous chapter, then all you can do is to enjoy your own tropical tree growing, while waiting for your ultimate reward – flowering! Indoors it can decide to go blooming any time of the year, whenever a branch is mature enough for this.

Plumeria buds always starts on the growing tips of branches. The first sight of an impending flowering is that new leaves stop growing and small claws of baby-leaves are moving a little bit out from the very center of the tip to give space to a tiny at first flower bud.

The bud will grow in size while it is also rising on own stock. During about two months flowers will separate from the bud on individual stems and will go through a transition from a little spin-out to a whirled together capsule of petals, which will finally open one day as probably the most beautiful flower on the Earth.

Each inflorescence will last for about one-two months, bearing flowers in different stages. If your tree has more than one branch they can flower simultaneously or on individual schedule. Don’t forget to share your pride while it lasts with your friends and neighbors and do it not only on-line, but in real life as well. Even if flowering Plumeria is a stunning photography subject, it should be enjoyed if possible by all senses as their smell is truly magnificent!

While a branch is flowering you will see 2-4 new tips forming around the inflorescence’s stalk. Each of them will grow into a new branch. Those are your new beginning to look forward to get rejoiced by the next flowering in about a year.

Other posts in this series:

Part 1: Introduction to Plumeria.
Part 2: Closer look. Plumeria cultivars. True or fake on eBay?
Part 3: How to start your own Plumeria indoors.
Part 4: Plumeria care and flowering indoors (this post).
Part 5: Plumeria problem-solving (coming soon).

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