Ornamental artillery plant, Pilea microphylla, aka gunpowder or pistol plant, military fern, or rockweed, is an herbaceous perennial.
It is one of about 600 types of non-stinging Pilea species in the Urticaceae, or nettle family.
This tropical species thrives outdoors year-round in Zones 11 to 12 as a short-lived evergreen perennial. It is also grown as an outdoor annual or indoor houseplant in all zones.
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In this article, we’ll discuss all you need to know to grow and care for your own artillery plant indoors.
It has a creeping growth habit and may reach mature dimensions of six to 18 inches high and 12 to 24 inches wide.
The artillery species has plump leaves like a succulent. They are either green or variegated pink and white, one-eighth to one-half inch long, and “obovate,” or rounded and narrower at the base. The leaves are arranged in opposing pairs, like a fern frond.
In nature, the species produces tiny pinkish flowers followed by brown fruits. And while flowering is unlikely to occur indoors, it’s fun to know about it because the names “artillery,” “gunpowder,” “military,” and “pistol” come from an unusual characteristic.
There are both male and female flowers, and the males literally propel pollen into the air, as in an aerial attack.
Historically speaking, the artillery species has undergone numerous botanical reclassifications by Swedish botanist Carl Linnaeus and later botanists, including Parietaria microphylla (1759), Pilea muscosa (1821), P. microphylla (1851), and P. trianthemoides var. microphylla (1869).
These synonyms and “basionyms,” or name equivalents and their predecessors, still pop up in plant searches, so it’s good to be familiar with them.
The artillery species is native to the Caribbean, Mexico, Central and South America, and the southeastern United States.
In its native habitat, it is a somewhat weedy, spreading ground cover that commonly sprouts between rocks and in lawns, in margins between land and water, and in masonry crevices.
The species has been introduced around the world, and is classified as invasive or at high risk for becoming invasive in many places because it readily naturalizes via stolons, or runner roots, as well as self-sown seed.
Today’s cultivated varieties are robust versions of the hardscrabble wild species. And while indoor cultivation does not pose a threat to the landscape, we do not recommend letting P. microphylla spend the summer outdoors in temperate zones as we do with many houseplants, in order to avoid inadvertently introducing it to the landscape.
This tropical species thrives best with a daytime temperature range of 65 to 85°F and 1000 to 2000 foot-candles of daylight, which is another way of saying bright indirect light.
Lower light is well-tolerated but usually causes shading to dark green, so don’t waste money on a variegated variety if you choose a dim location for your plant.
And growth may be more horizontal than upright. A little pruning of leggy stems contributes to a more compact form.
If you have a very dim setting, such as a windowless office, that you wish to add a plant to, you’ll need a grow light.
To grow your own P. microphylla, you’ll need to start from seed, take a stem cutting from an existing plant, divide an existing plant, or purchase a nursery start.
Outdoors, this is a vigorous self-sower that disperses tiny seeds with gusto, contributing to its invasive tendencies.
However, starting from seed may pose a challenge, as most retailers sell live plants and seeds can be hard to come by.
The artillery plant scientifically known as Pilea microphylla is a popular and relatively easy-to-care-for houseplant. It is loved for its lush green leaves and its unique method of dispersing pollen – with an audible “pop” that gives the impression of firing like an artillery shell.
This rapid growth and abundant seed production makes the artillery plant a great candidate for propagation from seed. However, timing is everything when it comes to collecting viable seeds from your plant Read on to learn about identifying seed maturity, techniques for harvesting, and proper storage of artillery plant seeds.
Understanding Your Artillery Plant’s Growth Cycle
Before trying to collect seeds from your artillery plant, it is important to understand its growth habits. Here are some key facts
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The artillery plant is capable of rapid growth when provided with its favored conditions of warm temps, high humidity, and bright indirect sunlight.
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During the active growing season, new foliage and seed pods are continuously produced.
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The seeds develop inside small green pods that turn light brown when ripe.
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Ripe seeds may begin passively dispersing from the pods, so timing the harvest is important.
Regular monitoring of your plant during the growing season will provide insight into when seed pods are reaching maturity.
How to Know When Seeds are Ready for Harvest
Timing is critical when collecting artillery plant seeds. Here are signs that the seeds are mature and ready for harvest:
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Pod color change – immature seed pods are green. As they ripen, the pods turn light brown.
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Pod texture – ripe seed pods will begin to dry out and feel brittle or papery to the touch.
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Pod splitting – gentle pressure should cause the pods to crack or split open, releasing the seeds inside.
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Seed dispersal – ripe seeds may start passively falling from the plants. Try tapping the pods and watching for seed release.
Once these signs are observed, move quickly to collect seeds to avoid losing them.
Recommended Techniques for Artillery Plant Seed Harvesting
When gathering ripe artillery plant seeds, you can employ various hands-on techniques:
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Manual plucking – Use your fingers or tweezers to remove individual pods once ripened. Take care not to damage stems and leaves.
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Paper bag method – Place small paper bag over pod and shake gently to release seeds inside. This contains dispersing seeds.
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Scissor harvesting – For hard to reach pods, carefully snip them off using small scissors without harming nearby foliage.
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Seed maturation monitoring – Check pods frequently as they ripen to pinpoint optimal harvesting time.
No matter the technique, handle the plant gently during harvesting to avoid impeding its future growth and seed production.
Proper Storage for Harvested Seeds
Once collected, artillery plant seeds must be properly stored to maintain viability for future propagation. Follow these tips:
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Allow seeds to fully dry before storage to prevent mold growth. Spread out on paper towels for a few days.
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Place dried seeds in an airtight container like a glass jar or plastic bag. Protects from pests and moisture.
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Store container of seeds in a cool, dark place like a cupboard. Avoid heat and sunlight.
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Label the container with species name and harvest date for easier reference later.
Stored correctly, artillery plant seeds can remain viable for 1-2 years before re-harvesting is required.
Learning when and how to collect seeds from your artillery plant takes some observation but will provide you with ample seeds for new plants. Monitoring seed pod development, moving quickly once ripened, and properly storing the bounty are key steps for success. With some practice, you’ll be able to keep your artillery plant population flourishing for years to come.
Frequency of Entities
Pilea microphylla: 6
Artillery plant: 18
Seed pods: 10
Seeds: 22
Harvesting: 7
Ripe: 5
Technique: 3
Storage: 5
From a Nursery Start/Transplanting
When you buy a pilea, it may be very young or more mature. To transplant it to another container, or to pot up a stem cutting or division, do the following:
Choose a vessel that is large enough to accommodate the plant, whatever its size, with two to three inches of growing room all around it. Be sure that it has one or more drainage holes.
Keep in mind that when it’s mature, this type of pilea may be between 12 and 24 inches wide. You will probably need to repot more than once before maturity and may want to keep the early containers on the inexpensive side.
At maturity, you may opt to select a hanging container to showcase the species’ creeping, trailing nature.
Buy potting soil that’s rich in organic matter, moisture-retentive, loose and airy, and well-draining. It will approximate the 5.0 to 6.0 pH that this tropical species prefers.
Place a single layer of pea gravel in the bottom to facilitate drainage, and then fill the vessel about halfway with potting soil.
Gently unearth the plant from its current pot.
Settle it in the potting medium so it sits at the same depth it was in the original container.
Backfill with soil and tamp it very lightly to hold the plant upright. Take care not to compact the soil. Light and airy is what you want to aim for.
If you are potting a rooted stem cutting, settle it in the soil, taking care not to injure the fledgling roots.
Bury the rooted end one inch deep in soil, tamp lightly and loosely backfill.
To transplant a division, you’ll want to settle it in much the same way, with about an inch of soil over the roots, at about the same height it was in its original vessel.
After potting, water until it runs out the bottom of the vessel, and repeat.
When all drainage has stopped, find a location with bright, indirect light. You may want to place the container on a single layer of pea gravel in a shallow, non-rusting pan. Add water to the pan until it comes just to the top of the gravel.
This is a great way to increase ambient humidity and replicate the natural habitat of a pilea plant.
One final note: With stems that are fleshy like a succulent, it’s easy to bruise or break them, so be sure to handle yours with care.
Once potted and watered, it’s time to apply a half-strength liquid or slow-release granular houseplant food. It’s best to apply this to wet soil to avoid burning tender roots and stems.
Feed again in the summer, and continue to feed once in spring and once in summer going forward.
Some gardeners recommend feeding more frequently, but overfeeding may prove to be a disaster resulting in a visible buildup of salts on the soil and container that inhibits water uptake.
In the event of a buildup, flush the pot through several times with water, and reduce feeding to once a year in the spring.
Keep the soil evenly moist by watering when the surface feels dry. Avoid oversaturation, as the roots rot easily, and reduce watering during winter dormancy. Just don’t let the pot completely dry out.
In addition, avoid wetting the leaves, especially in low-light locations, to avoid creating a breeding ground for the bacterial and fungal diseases we’ll discuss shortly.
P. macrophylla is not hard to grow when you remember to:
- Use an organically-rich potting soil that is loose, well-draining, and moisture-retentive.
- Avoid packing the soil down hard when potting. Instead, tamp loosely and leave lots of air holes to facilitate the flow of nutrients, oxygen, and water.
- Fertilize sparingly to avoid a buildup of salts, and flush several times as needed in the event of overfeeding.
- Maintain even moisture without oversaturation by watering when the soil surface feels dry.
This is an easy species to maintain. For a more compact shape, pinch off a few inches of the growing tips. If you like, use them to make new plants per the propagation instructions above.
If a fragile stem breaks, use clean pruners to remove the damaged portion. Be sure to cut just above a leaf node to encourage rapid regeneration.
Also, tap water is sometimes so alkaline or “hard” that it causes white spots to form on the leaves. If you note this issue, switch to distilled water.
Like many houseplants of tropical origin, P. microphylla thrives in bright, indirect light but it can tolerate a low-light placement.
Photo by Daderot, Wikimedia Commons, via
P. microphylla ‘Variegata’ is a variegated pink and white cultivar you may like to choose for a location with bright indirect light.
P. microphylla ‘Variegata.’ Photo by Forest & Kim Starr, Wikimedia Commons, via
For best results in low light, remember that a green variety is your best bet, as a variegated one is likely to shade to dark green anyway.
This species has not been widely developed, and options and availability are currently not extensive.
From a Stem Cutting
If you know someone with a plant already, you can get a head start by taking a cutting.
To propagate a stem cutting, make your cut about four inches from the tip of a growing stem at any time during the spring or summer.
Use clean shears and choose a spot to cut that’s just below a leaf node. This is a natural growing point, where roots will readily sprout.
Pinch off the lower leaves to reveal a bare stem about two inches long.
Place the bare stem in one inch of water in a narrow container that can support it, like an old unused drinking glass. There should be no leaves below the water line, as they will start to decay and foul the water.
Place the glass in a location with bright indirect sunlight, such as near a window with an opaque curtain. Avoid direct sunlight, as it may burn the foliage and roots with its intensity.
Change the water daily.
When roots sprout over the next couple of weeks, you’ll have a cutting that’s ready to pot up, which we’ll discuss shortly.
In addition to calling upon another gardener to assist you with the cutting method to get started with your first plant, you may be lucky enough to have a friend who is getting ready to repot. In this case, you can ask for a division.
This method involves unpotting and dividing one plant into two or more sections and transplanting the sections to their own containers.
You can learn how to divide an herbaceous perennial in our guide.
If you haven’t got a repotting friend, it’s time to get your wallet out.
Optimal Time to Harvest Trees
FAQ
How often should I water an artillery plant?
Why is my artillery fern turning brown?
Do artillery plants like humidity?
Can you propagate an artillery plant?
What is an artillery plant?
Artillery plants can also provide fine succulent-textured, green foliage for containers as the flowers are not showy. Related to the aluminum plant and the friendship plant of the genus Pilea, artillery plant info indicates this plant got its name from its dispersal of pollen.
How do you care for an artillery plant?
Part of your artillery plant care includes keeping the soil moist, but not soaked. Water when the soil is dry to the touch. Fertilization every few weeks promotes growth. Artillery plant info recommends feeding with a balanced houseplant food every five to six weeks. Artillery plant care also involves grooming the plant for desired shape.
Where should artillery plants be planted?
When considering where to grow artillery plants inside, choose a southern window, away from drafts. Artillery plant care includes placing the plant where day-time temperatures remain at 70 to 75 F. (21-24 C.) and 10 degrees cooler at night. Part of your artillery plant care includes keeping the soil moist, but not soaked.
Can artillery plants survive winter?
Winter hardy to USDA Zone 11-12, growing artillery plants in these zones may remain evergreen or die back in winter. However, growing artillery plants is not limited to those zones alone, as this specimen can be overwintered inside as a houseplant. A well draining soil or houseplant mixture is necessary to keep the plant happy.