Sensitive Plants and Insensitive Siblings: Growing Mimosa Pudica From Seed
Jan 03, 2019
Do you have a brother or sister? Have you ever repeatedly poked them, trying to elicit the "don't touch me!" whine? If you were a real pro, after being yelled at by your mom or dad, you'd then let your finger hover millimeters away from their arm or leg. You're not technically touching them, right?
Them: "Stop it!"
You: "Ha! I'm not touching you! I'm not touching you!"
Them: "Knock it off! Moooooooooooooom!"
At this point, your parents would put both of you in time-out. Years later (unless you do this as adults) your sibling would write a best-selling memoir, painting you as a sadistic sociopath, but at that moment, it was totally worth it. But now that your brother or sister has gone no-contact, what are you gonna do for fun?
Easy. Grow yourself some sensitive plants.
The sensitive plant's interactive beauty
Mimosa pudica is a fast-growing, frost-sensitive annual that rarely reaches more than 20 inches in height. It's best known for its touch-sensitive, bright green foliage. Leaves grow on pedicels in groups of four and each oval-shaped leaf is divided into 10 to 24 narrow leaflets which fold upward from either side of a central spine.
Those who have encountered young sensitive plants at nurseries might assume that its leaves are the main attraction, but we think the flowers deserve equal billing. The inflorescences are half-inch fluffy, pink or lilac flossy spheres, with each straight, silky filament ending in a bright yellow dot. Flowers usually emerge mid-summer in outdoor-established plants, becoming larger and more vibrant as the plant ages. When the flowers wilt, they look like pink shaggy plush toys; later, they give way to attractive green seed pods.
Why…and how…does the sensitive plant close its leaves?
We don't know for sure why M. pudica developed this characteristic, but the predominant theory is that the foliage's reduced surface area and its doubled-up thickness makes the plant less attractive to predators and herbivores, and less prone to rain damage. The folded leaves also expose the thornlike protrusions along M. pudica's hairy stem, reinforcing the plant's "DON'T TOUCH ME!" theme.
M. pudica folds its leaves in response to movement (seismonasty) or touch (thigmonasty). As each bi-pinnate compound leaf is poked, the thin leaflets fold up, beginning from the tip of the leaf and ending at the stem. The leaves unfold again in as few as ten seconds, or as long as ten minutes. When night falls, the plant's photosynthesis hits pause, triggering the plant to fold up and tuck itself into bed.
The University of British Columbia goes down the rabbit hole in describing the chemical chain reaction behind this behavior, but we'll summarize for you: Turgidity is the term for the water pressure in a plant that keeps it from drooping. This is why damaged stems or under-watered plants wilt. In sensitive plants, touch and vibration trigger an electrical signal among the plant's cells from the leaflets to the joint-like nodes in the leaf's central spine, restricting water flow and causing the leaflets to fold up.
Have you ever shuffled across a rug while wearing socks and then shocked your brother or sister, making them pee their pants and recoil in horror? It's something like that. And if you want to see a sensitive plant in action, click here.
Mimosa pudica: The "intelligent plant"
The epithet "stupid as a potted plant" doesn't apply to this species. According to a University of Western Australia study headed by Monica Gagliano, M. pudica can become habituated to certain stimuli to the point at which they "learn" not to fold up their leaves. Astonishingly, the plant retains this information for a month or more, reacting to new stimuli while "ignoring" that to which it was conditioned to ignore. So according to science, your sibling is the one who's dumber than a potted plant if they can't learn to tune out your obnoxious behavior.
If you haven't yet stumbled across the New York Botanical Garden's website, you're in for a treat. They've gathered a fascinating collection of poetry, artwork, history, and botanical data relating to sensitive plants and other species. Here's a preview:
As some young maid, to modest feeling true,
Shrinks from the world, and veils her charms from view,
At each slight touch her timid form receives,
The fair Mimosa folds her silken leaves;
And feel th' alternate change of night and day;
For when her mantle dusky Ev'ning throws,
She droops her head, and sinks to soft repose;
Nor till the morn dispels the shades of night,
Rears her meek brow, and wakes to life and light.
— Frances Arabella Rowden, A Poetical Introduction to the Study of Botany (1801)
Victorian era people were as obsessed with modesty and purity as they were with exotic plants, and the New York Botanical Garden's Poetic Botany pages propose that M. pudica's prudish behavior is part of the reason the plant was such a hit with poets and high-collared, corseted conservatory gardeners.
The sensitive plant's origins and history
The genus name Mimosa is derived from the brunch cocktail your frustrated mother drank with her sympathetic friends every Sunday afternoon. Or, maybe, it's a nod to the mimosa tree (Albizia julibrissin) of Asia, which has similarly-shaped leaves and shares the fluffy, pompom flowers. M. pudica is native to tropical zones in South and Central America, but both species are within the same subfamily (Mimosoideae) of the greater Fabaceae legume tribe.
Of course, we were clowning around with Mimosa's name origin; mimos (think "mime") is Latin for "performer" or "actor," and "osa" translates to "like" or "resembling." The idea behind the genus name is that the plant imitates life through its interaction with its environment.
According to the online Latin dictionary LatDict, pudica means "foul, stinking, decaying, offensive, tiresome, or pedantic," but most botanical texts translate pudica as "shrinking, shy, or bashful." The sensitive plant doesn't have much of an odor at all, and we're baffled as to how a plant can be both bashful and pedantic.
Other common names for M. pudica include:
- Shame plant
- Shameful plant
- Humble plant
- Intelligent plant
Sensitive plant's popularity with 17th and 18th century professional and amateur botanists, including Thomas Jefferson, have helped the plant naturalize in tropical areas outside its native range, and it's long been a popular hothouse plant and botanical garden favorite...especially among little kids that like to poke stuff to get a reaction.
Mimosa pudica's medicinal value
Sensitive plant's seeds are believed to help the lower intestine slough out buildup of...well, old poo. One herbal supplier even refers to M. pudica as the "Gut Scraper." Close your eyes for a minute and let that sink in for a minute.
Sensitive plant contains high levels of alkaloids, and we advise our customers to supervise pets and small children around these plants. If they don't get the hint from the spines, they could get sick after eating them.
Growing sensitive plants at home
Mimosa pudica is an exotic and unusual plant, but by no means does that make it a difficult species to grow yourself. Amaze your friends and trigger flashbacks among family members with potted sensitive plants, or just hoard them for your own enjoyment. They're also in demand as nursery plants, in case you're into hoarding cold, hard cash.
Find a spot in your garden or home where you can interact with them: Along pathways, in patio gardens, or potted in a sunny south-facing window. Wherever you plant them, be sure they get enough moisture and sunlight. Ground-level drip irrigation is ideal since sensitive plants have deep, spreading roots.
Because they're legumes, they help trap nitrogen from the air and make it available to other plants through the soil. While some gardening guides advise growing sensitive plants in poorer soils to improve nutrient values, we recommend you give them a humus-rich substrate for best results.
Here are some quick facts to help you find the right spot for your M. pudica plants:
- USDA Hardiness Zones: Grown as an outdoor annual in zones 3 to 11; may naturalize in zones 9 to 11.
- Sunlight Preferences: Full sun, shade intolerant.
- Moisture Requirements: Consistently moist but not wet.
- Soil Preferences: Loose, rich, well-drained soil with a pH between 6.6 and 7.5.
- Plant Height: 18" to 24" tall.
- Plant Width: 8" to 20" spread.
- Growth Habit: The plants grow in a somewhat floppy upright manner; up to a dozen flowers grow farther along the upper stem, beyond the foliage.
- Bloom Period: Mid-summer.
Sensitive plants are low-maintenance, but be on the lookout for aphids, red spider mites, and thrips. It will develop root or crown rot if you allow mulch to crowd its base or if you plant it in poorly-drained soil. Some insecticidal soaps will cause the leaves to turn brown or black, so we recommend a light "pressure wash" (using a hose, not an actual pressure washer) to force insect pests off the plants.
The sensitive plant has naturalized in Florida and other humid, marshy areas in the Southeastern United States. In tropical African regions, it's become a nuisance plant as there, it easily reseeds from the seedpods left behind after the flowers fade. For the most part, it's unlikely you'll be unleashing a plague on your environment, but if you're unsure, simply collect the pods before they ripen.
Growing Mimosa pudica from seed
Unless you live in frost-free zones with warm spring temperatures, we strongly recommend that you start your sensitive plant seeds indoors at least 6 to 8 weeks prior to the last spring frost. Be sure to use biodegradable seedling pots to reduce transplant shock. If you don't have a warm, sunny window, you'll want to use full-spectrum indoor growing lights.
- Seed Treatment: Gently roughen the seed coating with a few swipes of an Emory board, and soak for 20 minutes in hot water.
- When to Plant Outdoors: Direct-sow Mimosa pudica seeds once the soil has warmed to 70°F.
- Seed Depth: 1/8" deep; they need some sunlight to germinate.
- Seed Spacing: Plant or thin 12" to 18" apart; plant 2 to 3 seeds in each spot for best results.
- Days to Germination: Seven to 21 days at about 70°F.
Keep the seedbeds or nursery pots consistently moist using a spray bottle or the mist setting on your hose nozzle. We recommend placing a plastic bag with a few ventilating pinholes over the nursery pots to help retain moisture but be sure to remove the covering as soon as seedlings emerge. When it comes time to transplant your sensitive plant seedlings (wait until they're at least 4" tall or have at least 4 sets of leaves) thoroughly soak and then score the pots before placing them in the moistened garden bed. When growing Mimosa pudica from seed, don't let the plants dry out; we recommend drip irrigation or early-morning mist emitters.
Contact Seed Needs
Do you have a question about our products? Do you need some gardening tips? Like sensitive plants—and unlike many seed companies—we actually respond when you try to get in touch with us. You can contact us through our website or follow us on social media. (Is poking on Facebook still a thing?) in any case, it's our mission to carry the highest quality seeds and provide the best customer service possible within the retail seed industry.Be sure to bookmark our gardening blog for detailed growing tips for and cultural insight into our favorite plant species. We're always adding new content to complement our expanding line of seed varieties!