What Is Considered High Humidity in a House for Plants?

Houseplants need a certain level of humidity to stay healthy.

If you have plants inside your house, you might have to regulate the house's humidity to accommodate the plants' needs. If your house becomes too dry, the plants' leaves may begin to wither. An excessive amount of humidity might allow fungal infections to spread between plants much more easily than otherwise is possible. Each type of houseplant has a certain range of moisture it prefers.

Desert Dwellers

Cacti and other desert dwellers are accustomed to a low level of humidity. They do not require a lot of adjustments because they can withstand a humidity level down to 30 percent. If you want to care for cacti, just don't let your home's humidity level drop below 20 percent. You should have no problem doing that because houses normally have a 50 to 55 percent humidity level.

Most Houseplants

The majority of plants you may grow in your home prefer a humidity level from 70 to 80 percent. Inside a plant, the relative humidity amounts to about 100 percent and must stay about that level. Plants release some of their water into the air through pores called stomata as part of their metabolic process.

Tropical Houseplants

You might not feel comfortable in a home that has a relative humidity of 90 percent or higher. If you want to grow tropical plants in your house, however, you must keep them in a highly humid environment, leaving you with few choices. You could grow them in a terrarium or similar environment that can contain the high level of humidity and warm temperature the plants require.

Dangers of Excessive Humidity

A high level of humidity can affect not only your plants but your house negatively. Drywall surfaces tend to collect plenty of mold in humidity levels above 70 percent, and some plants may become susceptible to fungal diseases that spread over their leaves in high humidity. Regulating the humidity helps to keep your house and houseplants healthy.

References

• University of Saskatchewan: Humidity and Houseplants; Grant Wood
• University of Vermont Extension: Houseplants Need Humidity; Leonard Perry, Ph.D.