Air conditioning isn’t for everyone. It can reduce indoor humidity levels, leading to dry skin, irritated eyes, and dehydration. During peak summer months, it can also significantly increase energy bills.

Indoor plants are a great, cost-effective alternative to keeping your home cool during the summer.

Craig Morley, a houseplant expert from Budget Seeds, collaborated with housebuilder Barratt London to share the NASA-approved method of naturally cooling your home and the seven best plants to have in your home ahead of this season’s heat waves.

What’s Transpiration?

You may know the benefits of having indoor houseplants when it comes to improving the air quality in your home, but what about plants’ air-cooling qualities?

“Transpiration is the process by which water flows upwards through a plant, from the soil to the leaves and the stem. As well as delivering water and nutrients to the plant’s cells, this process keeps plants cool as water evaporates from the leaves,” says Morley.

According to the houseplant expert, transpiration also cools the area around the plant.

“NASA’s Earth Science Division proved this means plants can help combat rising temperatures caused by climate change. On a smaller scale, having houseplants in your home can help cool your home in summer—free, eco-friendly air conditioning, if you like,” Morley explains.

How to Promote Transpiration in Your Plants

Morley shares six tips to promote transpiration in your plants.

1. Keep Your Houseplants Watered

“If a plant is not watered often, this can reduce the rate of transpiration as the plant tries to conserve water. Giving your houseplants ample water will encourage transpiration and help to cool your home during hot weather,” says Morley.

2. Increase the Humidity

You can increase the humidity by placing your wet plant in a pebble tray. When water evaporates from the tray, there will be a bubble of humidity surrounding the plant. This has a similar effect as a humidifier.

3. Group Plants Together

Placing plants together is a great way to create a humid microclimate, which will help prevent them from drying out.

4. Upsize Your Pot

Plants placed in containers may transpire less because their roots are in a small space, which can lead to water stress. Opting for a bigger pot can help solve this issue.

5. Avoid Pruning in the Summer

According to Morley, pruning can decrease transpiration in a plant because it reduces water uptake.

6. Satisfy Your Plant’s Needs

Satisfy your plants’ needs so that they can be as efficient as possible in cooling your home. “Consult your plant’s care tag or use the internet to research ideal growing conditions,” Morley advises.

Best Air Conditioning Plants

Investing in the right indoor plants will help you cool your home this summer. According to Morley, each species has different leaf structures, with each affecting their rate of transpiration. Larger leaves have more ‘pores’ to release excess water, which means they have increased transpiration. Curved or folded leaves usually conserve water. “It’s also believed that a plant’s rate of transpiration improves with age. This is likely due to the increased surface area plants benefit from as they grow,” says Morley.

The top 7 indoor plants you should have in your home to stay cool this summer are:

1. Snake plant
2. Peace lily
3. Aloe vera
4. Bamboo palm
5. Boston fern
6. Golden pothos
7. Spider plant

Morley advises, “For anybody new to plant parenting, good low-maintenance choices include golden pothos, which are also valued for their air-purifying qualities, and spider plants, which are perfect for bathrooms because they enjoy moisture.”