Plumeria are generally very resilient plants, but they have some very specific soil requirements to get them settled into a new home. Whether you’re dealing with potted plumeria cuttings or mature plumeria plants, the soil requirements are fairly similar.
In this guide to the best soil for plumeria, we’ll cover what your plumeria flowers need to thrive, some of the science behind it, and exactly what kinds of compost are going to keep your plumeria blooms happy and healthy right through the growing season.
Plumeria Soil Requirements
Plumeria is an ornamental shrub that requires very specific acidity levels, not too high, not too low, but a little more acidic than your average garden compost mix.
I’ll move on to the specific requirements for each in a second, but first, let’s talk about why. When growing plumeria plants, your main aim is big blooms and vigorous lai flowers, not foliage growth. Foliage is important to a healthy plant so needs care, attention, and a little bit of potassium, but you’re looking for growing mediums, composts, and fertilizers that contain high amounts of phosphate, and are ideal slow-release, so any acidity won’t overwhelm the plant.
Acidity
Potted plumeria plants need slightly acid compost, between 6.4-6.8 which really is slightly acidic, like all tropical flowering plants, because they’re trying to take up nutrients that are rarer in cultivation. In garden soils, phosphate levels are low. They can be added with bone meal, or rock phosphate occasionally as an additive, but if the earth is neutral, or alkaline it inhibits the uptake of nutrients through plumeria roots.
If compost is too acidic, plumeria roots will burn and their root hairs will stop being able to take anything useful up to the leaves above. Conversely, if a growing medium isn’t acidic enough, the roots will happily take up water but the plant is unable to break down the nutrients or make use of them.
Drainage
Plumeria hate sitting in water, and incredibly drought-tolerant plants, so choosing compost with good drainage is essential. This can mean adding drainage to the soil through grit, sand, or vermiculite, but often loamy garden soils are enough to maintain well-drained plumeria growth.
Your plant really should not be watered in winter either, as outside its active growing season, while you have a plumeria outside of direct sun for most of the day, it is not able to take up nutrients.
Water Retention
While we suggest that plumeria likes drought, and drier conditions, some water retention is required in any plant, even cacti. In fact, cactus mixes have a good level of water retention to help you avoid over-watering them, and their watering regimen is actually quite similar.
Never water a plumeria, or cactus while it is still moist, and make sure the compost is holding water for the plant every year when growth appears by sitting the pot in a tray of water. By doing you, improve the water retention of any compost as the compost sucks water up from below, which opens up its cell structure and allows it to hold just enough water until the next watering.
Soil Types and Additives for Plumeria
Our instinct as gardeners is to use our own soils, composts, and additives as often as possible to boost flower production and blooms in our prized plants, but tropical plants like flowering plumeria trees can react very poorly to our own compost. Average garden compost in Europe and the Americas has a PH of around 8, which is alkaline and can reduce flowering, and cause more foliage growth rather than bigger blooms.
Here I want to discuss the pros and cons of each common type of compost you can make, or buy:
Garden Compost for Plumeria
While you can buy great compost for plumerias, it’s easy to make your own at home, but you’ll need a compost bin to get started.
Leaf Mould for Plumeria
Leaf mold, or leaf compost, is compost made up entirely of dried fallen leaves. By gathering them in autumn, you can have compost ready to harvest the following year. By the time it is ready to use it will be a black loamy consistency and quite light. It typically has better drainage than garden compost and is a lower PH (about 6.3), which is not quite acidic enough for plumeria, but a great base for some simple soil additives.
Peat Free Potting Compost for Plumeria
Potting Composts that contain peat are unsustainable, bad for the environment, and lead to excessive water retention around plumeria roots.
A good peat-free potting compost is difficult to achieve at home as most homemade composts are either neutral or slightly alkaline and have high water retention, so and for young plumeria cuttings, buying sterile compost from a garden center or online is an easy way to prevent bacteria in your frangipani plants.
Potting compost usually has a pH of between 6 and 8, so requires additives like coffee ground to lower the pH to plumeria’s acid requirements.
You can find great peat-free potting mixes in garden centers and DIY stores, just be sure to check the label for peat content.
Ericaceous Compost for Plumeria
Ericaceous compost is an excellent way to add more acidity to the soil mix when you pot on mature Plumeria. While it is too acidic by itself (usually 4-5 pH) you can use a mix of 90% potting compost to 10% ericaceous compost to create a perfect blend from plumeria.
Cactus Potting Mix
Vermiculite / Perlite for Plumeria
Perlite is the best additive for plumeria drainage as it is chemically inert. It’s a naturally occurring volcanic glass formed by heating obsidian so doesn’t retain in the compost, and thanks to its lightweight air-filled structure help to make plumeria containers much easier to move around.
Both are pH neutral and should be added at a ratio of 1 part perlite/vermiculite to 5 parts potting mix.
Sand / Horicultural Grit for Plumeria
Maintaining Plumeria Potting Soil
Soil Water Retention for Plumeria
Plumeria growing mediums should always be left to dry out between watering, and no water at all when temperatures drop in winter while the plants are subject to freezing temperatures and dormancy. In early spring when new growth appears, plumerias should be placed in a sunny spot with some afternoon shade to stop them overheating. Full sun will bake their leaves, but keeping them warm in a bright but indirectly lit spot in the house prevents humidity from building up after watering (this leads to common plumeria pests like spider mites)
During the growing season, aim for regular watering of your plumeria once a week in summer, but once per fortnight in spring and autumn. Tropical plants should be watered deeply every time, and allowed to dry out completely between watering.
Every 2-3 years repot your plumeria to provide better drainage, trim the plumeria root ball, and improve add some gentler water retention.
Soil Additives for Plumeria
To help maintain plumeria soil health and re-establish acidity levels there are some excellent simple additives you can add to compost either through watering or mulch. Coffee grounds help to improve acidity levels when a plumeria has used up all the container’s nutrients, and mulching with ground eggshells or bone meal is a useful way to add vital minerals back into the compost.
The most important measure of soil health is acidity, as, without acid, the plumeria can’t absorb nutrients, leading to lead drop, and leaves the turn yellow. If this happens, you need to boost acid levels.
Read our article on Plumeruia Fertilizers for more information on exactly what to look out for when buying fertilizers for Plumeria.
Acidity Regulators for Plumeria
The most important tool for plumeria growers, thanks to their preferred soil being acidic, is an acidity regulator. There are some simple ways to assess acidity, but nothing is easier than a pH meter that can be kept in the plumeria container all year round to track changes in acid levels and tell you exactly when additives are required.
It’s quick and easy to boost acid levels, but these acid measuring tools really help give you a better idea of when acid levels are dropping, allowing you to top them up before its too late
1. Sonkir Soil pH Meter
Often, a basic pH meter is all you need to track the acid levels in your plumeria containers. the simple two-pronged acidity pH test kit from Sonkir is waterproof and has the added bonus of reading light levels and moisture levels in your pot too.
Given that plumeria need light without full sun, and very strict watering, this is a great budget choice to tell you everything you need to know to fare for your plumeria and maintain compost conditions.
Pros
- Tests pH
- Great value
- Tests water & light levels too
Cons
- No connectivity to smart devices
- Not very durable
- Low accuracy
2. Apera Instruments Waterproof pH Tester kit
This digital pH meter helps to regulate soil, is highly accurate, and really easy to read with a handy digital screen attached to its contact test plates.
It’s battery-powered, so there’s no waiting around for it to charge either, with power that lasts up to 2000 hours.
the biggest benefit of this pH kit is that it can be used in water too, so as well as testing your compost, this will test the water, either from water butts or taps to give you an accurate acidity level reading.
Pros
- Highly accurate pH readings
- Fully waterproof
- Durable design
- Digital screen for easy reading
Cons
- Expensive
- Doesn’t test water or light levels
3. CNYST 2 in 1 Soil Moisture and PH Tester
While beauty isn’t exactly an obvious facto in choosing a pH regulator, this moisture and ph tester is a really neat little piece of kit, with a much higher build quality than most others in its price range.
As well as acid, it helps to measure moisture levels to stop your plumeria from getting wet feet in its new pot. Thanks to its plunging design it will remind you that in cold winters, watering should top completely, and to resume regular watering again in spring.
Pros
- Well built and durable
- Good value
- Clear dial for easy reading
- Measures both pH and moisture
- Accurate readings
Cons
- Doesn’t test light levels
4. Wanfei Plant Monitor Soil Test Kit
The Wanfei Plant Monitor is one of the most accurate, and affordable plant monitors available online, with an easy-to-use app that tells you up-to-date information about light, temperature, ph, and nutrients.
This incredible little tool will tell you everything you need to know about your plumeria and guide you if it needs some gentle support, gives clues to when it needs hard pruning, and even tell you how to help it bloom, to move to a little shade.
Pros
- The smart interface connects to your mobile phone o iOS and android
- Rechargeable
- Long battery life
- Accurate pH testing
- Also tests moisture, light, temperature, and nutrients
- Amazing value
Cons
- None
Plumeria Soil FAQs
What potting mixes are good for lai flowers?
A well-balanced potting mix that gives the right amount of nutrients, acidity, and moisture retention for plumeria is usually: 7 parts cactus mix, to 3 parts vermiculite or perlite. Always plant at the same depth when repotting.
What is the right pH level for frangipani potting mix?
Plumeria is native to Central America, with warmer temperatures and more acidic compost. They require at least six hours of light per day through to mid-fall and a pH of around 6.8.
Final Thoughts
To prevent root rot, plumerias need the right amount of nutrients, but more importantly, their soil needs to be acidic enough for them to process those nutrients.
I hope this guide to making the best compost for plumeria gets you on the way to either improving plant health and preventing rot or fungal infection, or just to bigger bright blooms. Either way, it’s important to stick to the basics above: slightly acidic compost, good drainage, and a regular watering routine to maintain good soil structure around the root ball.