As anyone who has ever parted with a dear plant knows, raising healthy flora is a daunting task. In addition to considering variables like water and sunlight, you need to be mindful of your plant’s soil and how often it needs to be replaced. All dirt may look the same when it stains your jeans, but the differences between garden soil and potting soil shouldn’t be ignored.

Outdoor plants and indoor plants have different needs, so it’s important to choose the right soil for the job. According to HGTV, garden soil is closest to the natural dirt you find in your backyard. It consists of regular topsoil mixed with nutrient-dense components like composted bark, mushrooms, and livestock manure. Its dense composition has high water retention, which is great for outdoor flowers, herbs, and vegetables that thrive with irregular hydration.

Water retention is less of an issue for houseplants, which should generally be watered on a regular basis. Potted plants benefit from a looser, fast-draining soil that gives their contained roots as much breathing room as possible. If you look at the ingredients in potting soil, you won’t find any actual dirt. instead, it’s made from a blend of materials like bark, sphagnum moss, perlite, vermiculite, compost, and coconut coir. This mixture gives houseplants the nutrients they need without exposing them to the fungi and pathogens potentially present in garden soil.

After determining the best soil type for your plants, the next step is figuring out how often it should be refreshed—if at all. If the roots of your houseplant are starting to poke through the drainage holes, that’s a sign it needs a bigger vessel and a fresh batch of soil. Early spring—when plants are already experiencing a surge of growth—is the best time to transfer them to a new pot. Plants that don’t need to be repotted fully can also benefit from being topped off with fresh potting soil this time of year. Here are more tips for keeping your houseplants alive.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article was originally published on www.mentalfloss.com as Garden Soil vs. Potting Soil: What's the Difference?.