A relative of the nettle, the aluminum plant is a lush house plant or a lovely low-lying plant in the subtropics. This evergreen perennial is admired for its silver and green foliage.
While it can be slightly finicky about its environment, it’s generally an easy grower. A tropical plant by nature, it prefers warmer climates and higher humidity. But don’t let that finicky nature dissuade you from growing it!
You’ll love the look of this perennial plant in your home or in your garden, and believe me, it’s worth the effort. So let’s talk Pilea cadierei, the aluminum plant!
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- Monterey Liqui-Cop Fungicide
Quick Care Guide
|Scientific Name||Pilea cadierei|
|Common Name(s)||Aluminum plant, watermelon pilea|
|Height & Spread||12″ tall, minimal spread. Dwarf cultivars 6″.|
|Light||Bright indirect light to partial shade|
|Soil||Loamy soil-based blend, well-draining|
|Water||Water when 1/4″ soil is dry, requires high humidity|
|Pests & Diseases||Mealybugs & spider mites. Also some leaf spot & rot issues.|
All About Aluminum Plant
Originating in Vietnam and China, the aluminum plant is sometimes called watermelon pilea. This is because of the distinctive silvery markings on its leaves. They resemble the stripes on a watermelon.
But it’s completely unrelated to watermelons, or to aluminum for that matter. Pilea cadierei is part of the nettle family, indigenous to tropical jungles. It doesn’t produce showy flowers, and is wholly grown for its foliage.
That foliage is fascinating! A vibrant mid-range green, each leaf looks like it’s been splashed with aluminum paint. The silvery areas are slightly raised above the leaf surface. Edged with fine, but not sharp teeth, the distinctly oval shape is tipped with a nice point.
These plants typically grow in a clustering or clumping fashion. They’ll reach heights of up to 12″, but there are shorter dwarf cultivars such as Pilea cadierei minima.
When the plant does flower, they are almost unnoticed. The flowers are a pale green hue and don’t stand out much. Even more rarely, they’ll produce an inedible fruit that houses their seeds. But if you’re growing an aluminum house plant, you probably won’t see it bloom.
Aluminum Plant Care
Let’s talk about the finer points of growing the watermelon pilea. With the right care, your plant will thrive indoors as a potted plant or outdoors in your tropical garden! Here are some growing tips to incorporate into your aluminum plant care regimen.
Light & Temperature
Tropical plants like Pilea cadierei are slightly picky about light and temperature. They like it warmer than outdoor conditions in the continental US typically provide. Because of this, they’re grown outdoors only in USDA zones 11 and 12, in locations like Hawaii or Puerto Rico.
For houseplant lovers, this makes it a perfect fit in most homes. As long as the average temperature in your house doesn’t drop below 60 degrees, your plant should be fine.
The complication comes from its lighting preferences. Watermelon Pilea cadierei prefers very bright but indirect light for at least four hours per day. Direct sunlight can cause sunburn and discoloration of the leaves. Too little sun will cause the plant to stretch out towards the brightest light source. This legginess can be unappealing.
For most of us, placing our plant in a north-facing window should provide plenty of bright indirect light. It will also prevent direct sun exposure. Be sure to turn your plant every few days to ensure even light exposure and prevent a lopsided plant. Outdoor plantings benefit from placements below tall trees, or offset from direct sun.
Water & Humidity
Evenly-moist soil during the growing season is best for this plant. Try to prevent soil which is soggy, as this can promote root rot conditions. When the top quarter inch of the soil from the soil surface downward is dry, water again. As the seasons shift towards the colder months of the year, the plant will need less watering as the soil dries less often.
Jungle-dwelling plants like aluminum plant get lots of humidity in their natural environment. They’ll still want it even in your home. Keep your plant out of the airflow from air conditioners or heaters to prevent drying out. Also, adding a humidifier or pebble tray with water beneath the plant helps. This raises the humidity directly around your plant. Misting it may also be of use.
Those of us who are lucky enough to have north-facing bathrooms with windows have an added bonus. This plant absolutely loves the humidity that builds up in most bathrooms. The steam from the shower will be a perfect match for your Pilea cadierei. Outdoors, dense plantings and moist soil provide the needed humidity.
Unlike some other types of houseplant, this one requires soil-based potting mixes. One which is loamy or peaty, but which drains off excess water well is a must. It should be able to retain a decent amount of moisture without going muddy.
That being said, make sure your container has drainage holes that assist in drainage. The soil’s pH is not a great concern when dealing with aluminum plant. A neutral range is simplest, but it will tolerate alkaline or acidic soils as well.
Aim for a soil which is fairly organic-rich if possible. In its natural environment, leaf mulch would naturally build up around the plants. The same is best for outdoor plantings.
Aluminum Plant Fertilizer
During the growing season, use a balanced water-soluble fertilizer every few weeks to once per month on your aluminum house plants and outdoor plants. A 5-5-5 fertilizer applied to the soil once a month should be plenty. If using a stronger water-soluble fertilizer, dilute it down so it is lower-potency.
As the fall weather sets in, slow down fertilizing frequency. Skip fertilizing in winter entirely, as the plant will be somewhat dormant.
Propagation of Aluminum Plants
Your aluminum house plants are best propagated from stem cuttings, as that’s the easiest method. While seed may sometimes be available, it can be more difficult to find and get started.
Take cuttings in the early spring or summer months. Select healthy stem tips for your cuttings, preferably new growth. Strip off all but the upper few leaves from the stem, and place it in your moistened soil blend.
Keep the soil moist, and the humidity up around the cutting which will readily root into the medium. It’s easiest to place a plastic bag or cover over the plant until it takes root. You will also need to provide warm conditions at around 70 degrees for good root development.
Pruning Your Aluminum Plant
Pinching back leggy growth will promote a more bushy growing habit. Find a joint where leaf buds are visible or where leaves have begun to grow. Pinch back the excess growth just above the leaves.
Turning the plant to ensure it has consistent light exposure can reduce legginess. It won’t entirely prevent it, but it at least slows down the inconsistent growth.
Many people will use the tips they’ve pinched back to propagate new plants from in the early spring. As these plants age, they all develop a leggy tendency. After a few years of growth, it may be easiest to simply replace your plant with a rooted cutting.
When your indoor plant starts to produce new growth in the spring, check the plant’s roots. If they are very tightly packed in the pot, it’s time to repot.
Prepare your soil blend, and use a pot no larger than 1″ wider than your current pot. Use your fingertips to loosen the root tangle, then plant at the same height it was at before. Use just enough new soil to fill the increased space.
If all the above growing tips sounded simple to do, then you’ll love the next part. Very few pests or diseases are common on aluminum plant. In fact, outside of a few minor issues, you’ll find it surprisingly trouble-free!
Most of the growing problems you’re likely to encounter will be related to light or water — the same kinds of issues you run into with other tropical species.
Too much sun can cause sunburn to the leaves of your aluminum plant. Your leaves may turn yellow and droop. To prevent this, provide ample bright indirect light, at at least four hours per day. Trim off burned leaves to keep the appearance nice.
Not enough light is also problematic. If a plant feels like it’s not getting enough, it’ll stretch towards the closest light source. This causes leggy and unattractive growth. Remember that an indirect light source is better than bright light from direct sunlight, or shade.
If the soil is too dry, your plant will wilt. Ensure the soil is evenly moist, and don’t allow it to become dry more than the top quarter inch beneath the surface.
Soggy soils can promote root rot conditions. Ensure excess water drains easily from the soil, but that it holds enough to sustain your plant! Drainage holes are a must.
Mealybug infestation is a possibility with your Pilea cadierei. If you find these little pests and their white fluff, act quickly. Letting them do their thing for too long may result in leaf drop. A cotton swab dipped in rubbing alcohol will make them release their grip on your plant. Neem oil is a good preventative spray.
Spider mites may also be an unfortunate house guest. You won’t see their larvae, but you’ll see the tiny mites themselves. They also cause leaf drop in large numbers. Neem can help kill off the larval phases. An organic pyrethrin spray will also eliminate these annoyances.
Xanthomonas leaf spot can be a problem. This causes the silvery patches to turn brown and dry, then drop out leaving holes.
Treatment of this form of leaf spot is rarely successful. The bacterial infection rapidly spreads through the plant’s tissues. Dispose of infected plants. Avoid overhead watering as a preventative measure.
Fungal leaf spots and blights such as anthracnose are also possible. These are easier to treat. Neem oil can act as a partial preventative. Liquid copper fungicides or biofungicides are also an option.
Overwatering can help pythium root rot develop. This causes the plant to wither, look stunted, or turn yellow. While some biofungicides are effective, it’s best to prevent it. Only water when your plant needs it.
Two other forms of blight which may occur are rhizoctonia blight and southern blight. Rhizoctonia blight can be treated with the same fungicidal treatments as pythium. However, southern blight is mostly untreatable and infected plants should be destroyed.
Frequently Asked Questions
Q: Is pilea cadierei poisonous to cats?
A: Nope! Aluminum plant is considered non-toxic to cats, dogs, and horses per the ASPCA. It’s safe around our furry friends!
Q: Why is it called an aluminum plant?
A: It’s called aluminum plant because it looks like it’s covered with silvery aluminum paint.
Q: How long does Aluminum plant live?
A: Most aluminum plants live for about 4 years at a time.
Q: Why is my aluminium plant dying?
A: Most of the problems associated with aluminum plants have to do with too much water retention in the soil. Check out the Troubleshooting part of this piece to verify.
Q: Can you grow an aluminum plant in water?
A: Much like other houseplants, you can grow cuttings of the aluminum plant in water. Make sure you change it frequently, and monitor the roots for signs of rot.
Q: What kind of soil does aluminum plant need?
A: A sandy and loamy soil is best for this plant.
Q: How often do you water an aluminum plant?
A: Allow the top quarter inch of the soil to dry between watering. Most of the time this occurs once or twice a week.