Sensitive plant, also commonly known as shy plant, is a creeping shrub or short-lived perennial known for its delicate purple pompom flowers and intriguing leaf movement. The leaves of a sensitive plant are lined with tiny hairs that are highly responsive to touch, temperature, and motion, folding inwards when triggered. The plant also closes its leaves at night. This response, called thigmomorphogenesis, is part of the plant’s natural defense mechanism. Sensitive plant grows best in full sunlight, well-draining and acidic soil, and temperatures between 65 and 75 degrees Fahrenheit.
Common Name | Sensitive plant, touch-me-not, shameplant, sleepy plant, shy plant |
Botanical Name | Mimosa pudica |
Family | Fabaceae |
Plant Type | Shrub, herbaceous, perennial, annual |
Mature Size | 18 in. tall, 1-5 ft. wide |
Sun Exposure | Full, partial |
Soil Type | Well-draining, loamy |
Soil pH | Acidic, neutral |
Bloom Time | Summer |
Flower Color | Purple, pink |
Hardiness Zones | 7–13 (USDA) |
Native Area | Central America, South America |
Sensitive Plant Care
Here are the main care requirements for growing a sensitive plant.
- Give this plant plenty of bright sunshine indoors or outdoors.
- Plant in well-draining, loamy soil for proper root growth.
- Water to keep soil moist, but never soggy. Reduce watering in the winter for indoor sensitive plants.
- Keep temperatures indoors or outdoors between 65 and 75 degrees Fahrenheit for best results.
- Keep levels of indoor humidity on the higher side for this plant and only grow it in the ground (with caution) in tropical or subtropical climates.
Warning
Mimosa pudica is invasive in tropical climates. Use caution when planting in the ground as it can spread quickly and naturalize readily through its many seeds. The plant's seed pods have clinging burrs, which allow the seeds to travel long distances.
Light
Sensitive plants are not very shade-tolerant. They thrive with eight hours of daylight and can tolerate partial shade, but languish badly in full shade. When growing them indoors, the ideal location is directly in front of or beside a bright sunny window. If the leaflets remain closed during the day, it indicates that the plant is not receiving enough light.
Soil
Well-draining, loamy soil is ideal for a sensitive plant growing in the landscape; its roots cannot survive in severely compacted soil. Enhance the soil with peat moss to improve drainage. In its natural environment, the sensitive plant lives in soils that are low in nutrients. Therefore, it does not require overly rich soil or frequent fertilizing.
When grown as a houseplant, a standard commercial potting mix is a good growing medium.
Water
Keep the soil consistently moist for a sensitive plant but not waterlogged. The sensitive plant cannot handle wet feet and will develop root rot if left sitting in excess water. As a general principle, water a sensitive plant once the top of the soil begins to dry out. Water sensitive plants a little more sparingly in the winter.
Temperature and Humidity
Sensitive plant can be grown as a short-lived outdoor perennial or shrubby ground cover in zones 7 to 13, but it is most often grown indoors as a potted houseplant. Potted specimens thrive in typical indoor temperatures of 65 to 75 degrees. The sensitive plant enjoys moderate to high humidity. Unless your house is particularly dry, the average household humidity should be sufficient for a sensitive plant. In regions where winter air is especially dry, run a humidifier close by or place the sensitive plant pot on top of a tray of pebbles filled with water to increase humidity.
If grown as potted patio plants, sensitive plants will perform best if moved indoors when temperatures stray outside the 65- to 75-degree ideal range.
Fertilizer
Sensitive plants occur naturally in nutrient-poor soil, so fertilization is generally not required. However, if desired, you can give the plant an extra boost during the growing season by applying a high-potassium liquid fertilizer diluted to half strength every few weeks. Always ensure that you water a sensitive plant before fertilizing it to avoid burning the delicate roots.
Types of Sensitive Plant
There are no named cultivars of sensitive plant commonly available. Where it is grown at all, it is the species form that is cultivated.
Another plant in the genus, Mimosa tenuiflorae or M. hostilis (Mimosa tree) is a small landscape tree that can be grown in zones 9 to 12.
Pruning
Prune a sensitive plant regularly to keep it full and bushy rather than leggy. You can prune a sensitive plant any time of the year. Since Mimosa pudica is a creeping plant, trim off trailing stems or train them to climb a trellis to keep the plant looking neat.
Propagating Sensitive Plant
Propagation of these plants is usually done by seed (see below), but it can also be done by stem cuttings. Here's how to do it:
- First, cut a 4- to 6-inch stem tip that contains at least one exposed leaf node.
- Plant the cutting in a small pot filled with a mixture of peat moss and perlite.
- Place the pot in a warm, bright spot, and cover it with clear plastic. In one to four weeks, the cutting will root and can be planted in a larger pot or in the garden.
How to Grow Sensitive Plant From Seed
Propagating sensitive plants by seed is the most reliable way to grow new plants. However, the seeds need a little encouragement to germinate. Follow these simple steps:
- Order seeds from a reputable source, or collect seeds from the dried seed pods left behind after the summer flowers have faded.
- In spring, prepare the seeds by scarifying—scratch the tough exterior with a sharp knife or soak them in water overnight.
- Sow the seeds in small pots filled with moistened potting mix. Cover them with a small amount of additional potting mix.
- Set the pot in a bright warm location. Germination usually takes only about one week.
- Pot up into larger containers as the roots fill the pot and become visible through the drainage holes in the pot.
Potting and Repotting Sensitive Plant
Sensitive plants grow fast and require multiple repottings if they outgrow their pot. It's time to transplant this plant when you notice the roots poking out of the drainage holes. You may need to do this several times in a single year. Choose a self-watering planter with drainage holes.
It's natural to see leaves drooping after repotting; give it some time—the plant will bounce back. If, after blooming, the plant deteriorates to a point where it is unattractive, save the seeds, discard the plant, and plant it again. Many growers plant new seeds each year, discarding the old plants after they flower.
Overwintering
Sensitive plants are considered perennial, but indoors, they deteriorate after blooming. The best strategy is often to grow sensitive plants as annuals, discarding them after you save their dried seeds to propagate new plants.
Watering should be slightly reduced for the winter months—both for indoor houseplants and garden plants that go into semi-dormancy for the winter.
Common Pests
Several pests are common to sensitive plants. These include spider mites and mimosa webworms, both of which wrap the leaves of the sensitive plant in webs that hinder their responsive closing. Sensitive plants are also susceptible to other common houseplant pests such as mealybugs and thrips. Spraying with a non-toxic horticultural oil is an effective treatment for these common houseplant pests.
Fortunately, sensitive plants are not especially prone to any diseases.
How to Get Sensitive Plant to Bloom
How Long Does Sensitive Plant Bloom?
Sensitive plant is usually grown for its delicate foliage that reacts in such a unique fashion to physical touch and other stimuli, so the short-lived pink-purple pompom flowers that sometimes appear through the summer (May through September) are a pure bonus.
What Do Sensitive Plant Flowers Look and Smell Like?
These fuzzy pink-purple pompom flowers do not have a distinctive smell. However, research has uncovered a foul odor that it uses as a defense mechanism when its roots are aggressively disturbed or ripped from the ground.
How to Encourage More Blooms
When blooms do not appear, it is usually because the plant is not getting enough light, which is a common issue with indoor houseplants. Try moving your plant to a sunny outdoor location for the spring and early summer months, or supplement your indoor plants with artificial light, which may stimulate more flowers.
A lack of flowers can also be caused by temperature extremes. Try to keep the plant in the ideal 65- to 75-degree range. Plants that spend time in extreme temperatures will often refuse to flower.
Caring for Sensitive Plant After It Blooms
This plant declines after it blooms indoors. There is no need to deadhead. Simply save seeds and replant if you desire.
Common Problems With Sensitive Plant
If your sensitive plant is dying, it does not necessarily mean that you have not taken good care of it. Here are things to look for when growing this plant:
Quickly Declining
First-time growers using sensitive plant as an indoor houseplant are sometimes surprised by how fast the plant declines and they wonder why their sensitive plant keeps dying. Most common houseplants are tropical evergreen perennials that can live for many years if cared for properly, but sensitive plant is not such a species—it will begin to decline immediately after it flowers for the first time. Efforts to prolong its life usually have little effect. Instead, it's best to simply save some seeds from the plant, plant a new specimen, and discard the parent plant after its appearance begins to decline.
Leggy Stems
These plants are also prone to developing leggy stems without much foliage—this is usually a response to inadequate sunlight. Make sure the plant gets at least eight hours of daylight—supplemented with artificial light if necessary—and prune back the stems frequently to keep the plant bushy and full.
Yellow or Brown Leaves
Yellowing or browning of the leaves can have a variety of causes. Brown or yellow leaf tips can be a sign of dry air, which is especially a problem in heated rooms with low humidity. Mist the plant regularly or place a humidifier nearby.
When the lower leaves turn yellow, the plant may be overwatered. Yellow leaves can also be caused by a lack of light, nutrient deficiency, or temperatures below 60 degrees Fahrenheit, which is too cold for sensitive plant.
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How exactly does this plant close its leaves in response to touch?
The thigmonastic responses to touch are possible because the leaves of the sensitive plant have a hinge-like mechanism containing motor cells that work in opposite actions. The plants react to stimuli by releasing chemicals that cause water to flow out of the motor cells on one side and into matching cells on the other side. This flow creates pressure that causes those cells to collapse or expand, making the leaflet squeeze shut. Left undisturbed the leaflet slowly opens again after a few minutes.
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If this plant is so short-lived, how can it be so invasive?
One sensitive plant may produce as many as 700 seeds that are easily transported by clinging seed pods or distributed by the wind. Some seeds germinate quickly but others may remain in the soil for months or even years until the hard coatings break down and allow germination. New plants can spring up miles away from the parent plant years after the parent plant has died.
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Is there any benefit to sensitive plant in the landscape?
Although Mimosa pudica is usually regarded as a weed when it escapes garden cultivation, sensitive plant is known to increase nitrogen and potassium in the soil—much like other members of the legume family do. Some studies show that some sensitive plant species can remove arsenic and heavy metals from contaminated soils. If you want to plant a less controversial Mimosa species in your landscape, consider sunshine mimosa, also called powderpuff mimosa (Mimosa strigillosa). This perennial wildflower is native to the southeastern United States and is an important pollinator plant. It is grown from seed and can even be planted in place of a lawn.