This fascinating houseplant's leaves curl up when touched.
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Mimosa pudica or sensitive plant
Credit: Helen Keane/Getty Images

More commonly known as the sensitive plant or touch-me-not plant, Mimosa pudica is a tropical shrub that closes its leaves when touched. The plant is native to Central and South America and features delicate, fern-like leaves with light purple pom-pom-shaped flowers. It's part of the legume family Fabaceae. The touch-me-not plant is a popular houseplant due to its relatively easy maintenance and interesting ability to recoil when touched. Here's how to grow and care for your touch-me-not plant.

Why Do the Leaves Close When Touched?

The burning question most people have about the sensitive plant is why its leaves close when touched. The quick answer is that it's a form of protection. The leaves of the Mimosa pudica are not just sensitive to touch, but also temperature and light. When you run your fingers over them, the leaves will fold up and remain closed for a few minutes. The leaves will also close from other external stimuli, like loss of light and rapid cooling or heating. 

Like any plant, the Mimosa pudica has water and other minerals stored in its leaves. The closing effect is due to a change in turgor pressure (the amount of water pressure in the cell pushing up against the cell wall). Scientists hypothesize that the closing of the leaves makes the plant appear smaller, while exposing the sharp spines on the plant stems, therefore deterring herbivores and insects from eating the plant.

Is it Bad to Touch a Touch-Me-Not Plant?

Although one of its common names is the touch-me-not plant, Mimosa pudica is not harmed when touched, and it will not harm you either. It earned this particular nickname because of its rapid response to touch. Mimosa pudica is a fun plant to have around the home and makes an interesting conversation piece when guests stop by.

Sensitive Plant Care

Caring for the captivating Mimosa pudica isn't difficult once you understand what it needs. It can be grown indoors or outdoors, but requires the same care and attention in either location.

Light

The sensitive plant needs bright light up to eight hours a day. It can even tolerate some direct sunlight. If it doesn't get enough sunlight, the leaves may close up (one of its triggers) and won't produce blooms. As a houseplant, an east-facing window is ideal. However, if you lack the proper light, you can supplement with a full-spectrum fluorescent grow light. Outdoors, plant Mimosa pudica in full sun or partial shade (as long as it gets its eight hours of sun per day). 

Soil

In its native environment, the sensitive plant grows in nutrient-poor soil. However, it does not tolerate compacted soil or soil that does not drain. A well-draining, loamy soil is best for the touch-me-not-plant, both indoors and outside.

Water

This plant likes consistently moist soil but not wet, soggy soil. Too much water can lead to root rot. The best way to keep the soil consistently moist is to plant it in a pot with drainage and water it when the top of the soil begins to dry out. If your Mimosa pudica is planted in the ground, make sure you modify the soil to improve drainage before planting, and water it when the top inch or so begins to dry. 

Temperature

The touch-me-not plant is a tropical plant that needs a temperature range of 60 to 85 degrees Fahrenheit to sustain healthy growth and produce flowers. Since most indoor environments fall within that range, it's perfect for a houseplant. Its USDA zone for outdoors is 9 to 11. If you live outside those zones, you can grow the sensitive plant as an annual or bring it indoors for the winter. 

Size

Mimosa pudica plants can reach a height of 5 feet. However, the average size is around 1 to 3 feet. The size of its pot and growing conditions will also affect its size indoors. 

Fertilizer

These plants do not require much when it comes to nutrients. However, to give them a boost during the growing season, apply a high-potassium liquid fertilizer diluted to half strength every few weeks.

How to Propagate Mimosa Pudica

The sensitive plant is most often propagated from seeds. Sow the seeds in a mix of moist peat moss and perlite, then place clear plastic above the planting medium to help lock in humidity. The seeds should sprout in 14 to 21 days. The sensitive pant can also be propagated with a cutting. Cut a section that has at least one leaf node. Place the cutting in a growing medium of moist peat moss and perlite and cover with a plastic bag or plastic wrap. Roots should establish in a couple of weeks.