Millennials might be “killing” napkins, chain restaurants, and golf. But one thing the generation that just came of age loves to do is garden. The millennial green thumb is having a huge impact on urban home design, with more renters than ever filling their living spaces with potted plants and mini-plots of carefully tilled soil.

One of the hottest trends in home gardening is the idea of a living wall—a wall virtually covered in foliage. The benefits of dedicating a large portion of your wall space to plants are numerous, but there are certain things to consider before jumping in with both trowels. Here’s three things to know before you build a living wall.

1. Living walls help you save energy

This is a blog about saving energy, so we would be remiss if we failed to explain how a wall of plants, well, saves you energy! According to the folks at Ambius, “Unlike brick or concrete, plant surfaces don’t store up solar energy, but reflect it. Both interior and exterior walls help to actively cool the air in summer by a process called evapotranspiration, reducing the need to cool the building. (A living wall) will insulate the building and reduce energy costs for heating the building in winter as well.”

2. Know your limitations

Some plants require more management than others. A croton, for example, requires half a dozen hours of sunlight and near constant watering in order to survive. If you know your lifestyle or gardening skills won’t be commensurate with the amount of time it takes to keep a finicky plant alive, plan realistically. There’s nothing wrong with a living wall of succulents.

3. Know your price range

Like many energy saving measures, living walls are an investment. Know how much you are willing to pay up front—according to Housetrends, living walls run around $90-130 per square foot for installation and irrigation. And know how long you plan to live in your dwelling so you can make the investment worth it. If you can swing it, now might be the perfect time to make your walls come alive.