The Aluminum Plant (also called the Watermelon Pilea) is a beautifully lush and multicolored houseplant. The metallic silver and green foliage of this evergreen perennial is widely beloved by many gardeners.
While it can be a little picky even in its natural habitat, Pilea Cadierei (sometimes spelled pilea cadieri) is generally a simple plant to grow. As a perennial and tropical plant, it prefers warmer conditions and a humid environment. But don’t let its needs put you off from growing at home!
You’ll adore the beauty of this dramatic plant wherever you choose to grow it, and trust me when I say it’s well worth the effort. So, let’s get into Pilea Cadierei, the Aluminum Plant!
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Table of Contents
Aluminum Plant Details
Scientific Name: Pilea Cadierei
Common Name: Aluminum Plant, Watermelon Pilea
Plant Type: Herbaceous perennial
Native Region: North Africa
Mature Size: 12″ tall, moderate spread. Dwarf cultivars: 6″
Blooming & Flowers: Rarely blooms, tiny white flowers
Sun: At least four hours of bright but indirect light, daily
Water & Humidity: Water when top 1/4″ soil is dry, requires high humidity
Soil: Loamy soil-based blend, well-draining, sandy soil mixture
Soil pH: Slightly acidic to neutral
Hardiness Zones: 9B-11, USA
Pests & Diseases: Mealybugs & spider mites. Also, some leaf spot & stem rot issues.
Where To Purchase The Aluminum Plant
You can find the Aluminum plant in a local garden center, or you can purchase it from an online retailer. We’ve heard great things about Etsy’s options for houseplants. You can also purchase them on Amazon, which is incredibly convenient.
The Aluminum Plant, or aluminium plant if you’re from the UK, was initially presented to the western world in 1928 by noted French botanists Andres Guillaumin and François Gagnepain while exploring the flora of Vietnam, which was still a French territory at the time. It was named after a fellow botanist and countryman, Father Léopold Michel Cadière, a well-known missionary in what was then Indochina.
Despite its name, it has nothing to do with watermelons– or metal, for that matter. This Cadierei species of Pilea is a ‘nettle’ (a prickly hair-covered herbaceous plant with sharp leaves), native to tropical jungles. It has no flashy flowers and is only cultivated for its aesthetic foliage.
Pilea Cadierei was introduced in the United States shortly after its botanical classification but didn’t become popular until the 1970s houseplant boom and has remained a favorite ever since. When looking at the silver markings on each of its dark green leaves, it’s easy to understand its popularity! Furthermore, with the proper care and growing conditions, it’s an excellent plant for first-time houseplant owners.
Flowers & Foliage
While the Aluminum Pilea does flower on rare occasions, the tiny white blooms are not particularly attractive. The blooms are a faint green color that blends in with the background. Even less frequently, they’ll produce an inedible fruit that contains their seeds.
To redirect energy toward the remarkable leaf growth, remove the flowers as soon as they blossom. Pilea Cadierei can grow to be about twelve inches tall, generally developing in clusters or clumps of stalks. Along with its modest height, the aluminum plant also has a bit of a spreading habit.
Pilea Cadierei Minima, a dwarf cultivar, is also available and grows to a height of about four inches.
Each leaf has a vivid mid-range green that appears to have been splattered with aluminum paint. The silver patterns are lifted slightly above the leaf surface. The distinctly oval shape is topped with a beautiful point and edged with delicate, but not sharp, teeth.
Aluminum Plant Care
Care of a Pilea Aluminum Plant is generally straightforward, although the plant can be demanding about its growing circumstances. The most typical challenge is inspecting the entire plant each spring for excessive root growth.
When you first buy the plant, it’s good to put it in a pot slightly larger than necessary. The root system of the Aluminum Plant can outgrow your pot and breakthrough its container. Start by potting a size up the first year, then transplanting it into a larger pot each year after that.
Light & Temperature
Pilea Cadierei is a tropical plant sensitive to bright light and intense temperature as a relatively low light plant. It prefers a temperature range warmer than that offered across the continental United States, though plant lovers can find it in other areas of North America. As a result, the Aluminum Plant is almost exclusively produced in the outdoor conditions provided by USDA zones 11 and 12 in places like Hawaii or Puerto Rico.
In terms of heat– or lack thereof– your plant should be alright as long as the average room temperature in your home doesn’t go below 60º Fahrenheit, making it an excellent option in most homes for houseplant enthusiasts. If you’re comfortable, your Pilea likely is too!
Most difficulty with this plant stems (pun intended) from its lighting preferences. Watermelon Pilea prefers indirect lighting that’s bright but not harsh. Sunburn and browning of the deep green oval leaves can occur when exposed to direct sunlight.
When there’s insufficient sunlight, the plant will spread out towards the brightest and closest light source. When it reaches toward the light, it might appear “leggy” and unattractive.
For most of us, putting Aluminum Pilea in a north-facing window will provide plenty of light while protecting it from the direct sun. Turn your plant every few days to maintain even light exposure and to avoid a lopsided growth pattern.
Water & Humidity
During the growing season, this Pilea plant prefers evenly moist soil. Do your best to avoid soggy soil because it can create root rot conditions. Water again when the top quarter-inch of soil is dry. The plant needs less watering as the seasons change, especially when entering the year’s colder months.
Plants that originate in the jungle, such as the Aluminum Plant, are exposed to a high humidity level in their native environments. They’ll desire the extra humidity even if you think you can’t offer it to them. To keep it from drying out, position your Pilea Cadierei away from the airflow of air conditioners or heaters.
It also helps to place a humidifier or a pebble tray with water beneath the plant. Nearby evaporating water increases the amount of humidity directly around your plant. Misting it may also be beneficial.
Those of us who have north-facing bathrooms with windows have an added advantage. Watermelon Pilea adores the dampness that accumulates in most bathrooms. The steam from the shower will be an ideal complement to your Aluminum Plant.
Though Pilea Cadierei is most commonly seen as a potted plant, outdoor gardeners should note that they can grow it near ponds, especially in warmer climates. On the subject of water, this species is sometimes actually sold as an aquarium plant!
However, similar to the purple waffle plant, we don’t recommend using it in aquariums. It’s not a true aquatic plant and will likely die. If it remains underwater, it’ll create a mess, necessitate more regular tank cleanings, and is not a wise investment. If you want a plant for your fish tank, get a genuinely aquatic plant.
Soil & Fertilizer
The Aluminum Pilea, unlike some houseplants, needs a soil-based potting mix and plenty of organic matter. A loamy or peaty soil that drains excess water is also required. The growing medium should be able to keep a reasonable amount of moisture without becoming muddy.
If at all feasible, aim for a soil that is somewhat organically rich, as leaf mulch would’ve naturally accumulated around the plant in its natural environment. Peat moss is an excellent addition to your pot or vessel, or any organic matter that’s at least some parts peat.
Once a month during the growing season, apply a balanced, water-soluble fertilizer. Once a month, a 5-5-5 fertilizer applied to the soil should be enough. If you’re using a more potent water-soluble fertilizer, dilute it first.
Reduce the frequency of fertilization as fall weather arrives. Because the plant will be mostly dormant in the winter months, don’t fertilize it at all. However, it may need additional organic matter during dry weather.
When fine-tuning your Aluminum Plant setup, the soil’s pH level shouldn’t be a significant factor. The neutral range is most common, but it can also withstand slightly alkaline or acidic soils.
Repotting & Placement
When your plant begins to sprout new and healthy growth in the spring, inspect the Aluminum Plant’s roots. It’s time to repot if they’re very closely packed in the growing vessel.
Prepare a rich soil mix and use a container no more than 1 inch wider than the current pot. Burry the Pilea Cadierei at the same height as before after loosening the root tangle with your fingertips. Use only enough fresh dirt to fill the extra space.
Aluminum Plants thrive best in partial shade when grown outside, as they can’t withstand too much sun, or else the wide bushy leaves can scorch. When growing inside, place it somewhat dark that doesn’t receive much light. Otherwise, the stems will likely become gangly, and the plant will not thrive.
When potting or repotting the Pilea Cadierei, follow these simple steps:
- Fill a suitable-sized container that has good drainage from the bottom about a fourth full with a fertile, well-draining potting mix. Use water to compact the soil lightly.
- Place the Aluminum Plant in the center of the pot, being careful not to damage the succulent-like leaves, and fill it in with soil. Plant the Aluminum Plant no deeper than it was growing before or with the base of the stems about two inches from the surface.
- Press the soil around the base of the Aluminum Plant and water it again until the water flows out of the bottom drainage holes.
Propagation & Pruning
Utilizing Stem tip cuttings is the most convenient way to reproduce your plant. While seeds are sometimes available, they can be challenging to locate and start.
Take stem cuttings in the early spring or late summer months. Choose those with a healthy rate of growth, ideally new growth, for your cuttings. Remove all but the top few leaves from the stem and place the plant in a wet soil mixture.
Maintain moisture in the soil and a high level of humidity surrounding the cutting. It’s easiest to cover the plant with a plastic bag or other enclosure until the Pilea Cadierei takes root. You’ll also need to provide warm conditions for the plant– around 70 degrees F.– for proper root development.
Pinching back leggy growth encourages bushier and fuller growth tendencies. Locate a joint with visible leaf buds or where lower leaves have begun to sprout and pinch the stem tips. Remove any excess growth just above the leaves by pinching it back.
You can reduce legginess by turning and rotating the plant to maintain continuous light exposure. The regular rotation might not wholly prevent gangly growth, but it will at least lessen erratic stemming patterns.
Many people use the growing tips of Pilea houseplants that they’ve plucked back to propagate new plants in the early spring. All of these plants get leggy as they age. After a few years of development, replacing your plant with a rooted cutting may be the simplest solution.
Aluminum Plant Problems
The majority of the developing issues Pilea Cadierei faces are related to light or water.
Sunburn might occur if the Aluminum Plant receives too much direct sunlight. The leaves of your plant may turn yellow and droop. To avoid this, provide plenty of bright but indirect illumination. To maintain a pretty appearance, remove any burned leaves.
Inadequate lighting is also a common issue. If a plant doesn’t get enough light, it will stretch towards the nearest light source. This stretching results in leggy, unsightly growth.
The Aluminum Pilea will also wilt if the soil is too dry. Make sure the soil is evenly moist, and don’t let it dry out more than a fourth of an inch below the surface.
Root rot conditions can be exacerbated by wet soil. Ensure that excess water drains from the dirt while yet holding enough water to nourish your plant!
Your Pilea Cadierei might get infested with mealybugs. Act quickly if you come across these tiny parasites and their white fluff. The bugs will release from your plant with a cotton swab dipped in rubbing alcohol. Neem oil is also an excellent preventative spray.
Spider mites could also be some unwelcome house guests. You won’t see their larvae, but you will see the small mites. Neem can aid in their eradication during larval stages. Home growers can also eliminate these annoyances with an organic pyrethrin spray.
Aluminum Plants can be affected by Xanthomonas (plant bacteria) leaf spots. As a result, the silver foliage gets dark and dry, eventually falling out and leaving holes.
Unfortunately, treatment for this type of leaf spot is rarely effective. The bacterial infection spreads quickly through the plant’s tissues, so you’re better off just getting rid of diseased plants. As a precautionary step, avoid constant overhead watering (i.e., an automotive system).
There’s also the possibility of fungal leaf spots and blights such as anthracnose. These are not too difficult to treat. Neem oil can be used as a precautionary measure. There are other liquid copper fungicides and bio-fungicides available, too.
Overwatering might promote the growth of Pythium (a plant parasite) root rot. As a result, the plant will wither, or become stunted and yellow. While some bio-fungicides are efficient, it’s advisable to avoid them and simply water the Pilea Cadierei only when required.
Rhizoctonia Blight and Southern Blight are two other types of diseases that can develop in the Aluminum Plant. The same fungicidal treatments that are used to cure pythium can be used to treat Rhizoctonia Blight. Southern Blight, on the other hand, is generally untreatable and will likely kill all afflicted plants.
According to some trustworthy sources, the Aluminum Plant is toxic to animals, while others claim it’s not. Regardless, it’s best to err on the side of caution and keep your pets and children away from the plant.
As a generally easygoing house plant, the Aluminum Plant is known as a crowd favorite for its ability to please its owners. Despite the threat of pests, diseases, and other problems, when cultivated indoors, Aluminum Plants are expected to thrive because of how fast they can expand.
If pruned back in the spring, an indoor Aluminum Plant can last for one to two years, although many people start a new plant every year from root cuttings taken off of the mother plant. The Pilea cadierei plant will continue to be a magnificent addition to your indoor garden for years to come as long as it receives the water and bright, indirect light it requires.
If you’re looking for a new houseplant, Pilea Cadierei is an excellent choice, with its general hardiness and stunning appearance. Check out its sister plants, too, the Artillery Plant (Pilea Microphylla) and the Friendship Plant (Pilea Involucrata), as they are just as beautiful in their own ways. Your efforts will be rewarded with magnificent tropical greenery that you’ll adore as displayed in your home!