Eco Greenhouse Heating with Water Bottles

Of course, keeping the temperature inside stable takes some effort — but with a few smart solutions, including an eco-friendly option, it becomes much easier.

1. Reuse and Recycle

Throughout spring and summer, start collecting plastic bottles, food containers, and cups — with lids and caps.
Wash them thoroughly and store them until autumn. Even in fall or winter, you can gather a good amount or ask friends and family for help.

2. Find the Sunniest Wall

Next, determine which wall of your greenhouse gets the most sun during the day.
Measure the wall and compare it to the size of your containers — this will help you figure out how many you’ll need to cover the entire area.
Mount shelves along this wall if necessary — you may need to build or buy a few extras.

3. Fill with Water

Fill each container with regular tap water.
Add a small amount of black paint to the water — just enough to darken it. Any type of paint will do. Mix well and seal the containers tightly.

4. Arrange the Bottles

Place the closed bottles on the shelves along the sunniest wall. Try to cover the entire surface — or at least two-thirds, especially the upper area.
During the day, the sun will heat the dark water, and at night, the stored warmth will slowly release into the greenhouse, keeping your plants cozy.

This method is not only simple and sustainable, but it also helps reduce waste and energy use.
You’re recycling plastic, avoiding electric or gas heating, and making your greenhouse something to be proud of — even in winter.