No gardener can have a green thumb without a little help. That help—okay, maybe it’s a lot of help—comes from the soil in which the plants grow. Even the best plants and bulbs will struggle if you don’t choose the right kind of potting soil for your project. And potting soil isn’t only used for indoor plants; it’s also essential for outdoor gardening.
What are you going to plant?
The type of plant and where you’re planting it will determine which potting soil you should use. For example, azaleas thrive in acidic soil. You can add specific ingredients from potting soil to the bottom of a planting hole, or even on top to enrich depleted soil. When you’re ready to plant, dig the hole for transplanting a few inches deeper than usual, or create your own soil mixture. For azaleas, a good mixture would include sand, mold, some manure, and peat moss. Once you have your mixture, place several inches at the bottom of the hole, position the azalea, and cover it with the remaining acidic mixture. This ensures your plant will have the ideal soil to grow and thrive.
Types of Potting Soil
There seems to be a special mixture for every type of plant. Cacti love loamy soil, orchids need special nutrients, and bulbs thrive with a lot of bone meal. There are even potting mixes designed for shady areas and others for full sun. The options are endless. Below are some common organic ingredients found in certain types of potting soil:
- Humus: Decayed organic material that holds moisture in the soil while also providing nutrients and aeration.
- Manure: Organic, odorless farm byproducts (refined manure) that provide valuable nutrients for your plants without the unpleasant smell.
- Peat Moss: A moisture-retaining material that keeps roots moist while providing the aeration needed for healthy growth.
- Sand: Helps with drainage, preventing plant roots from being saturated by heavy rains.
Other ingredients in potting soil may be inorganic. Some mixtures include wood chips, small sticks, charcoal, or materials like Perlite and Vermiculite, which are silica-based products designed to hold moisture.
Making Your Own Potting Soil
If you have a large yard or space to store ingredients, you can create your own potting soil recipes. The ingredients don’t need to be stored inside, but you should keep them out of the elements, such as rain and snow, to prevent the nutrients from being washed away before use.
Care of Potting Soil
This might seem like an odd concept—who takes care of dirt? You should, if you want healthy plants. Whether you buy pre-mixed soil or create your own, it should be sterilized to eliminate any harmful bacteria or weeds.
Sterilization can be done in small batches in the oven or in larger batches under the sun. To sterilize in the oven, spread the soil on a cookie sheet, bake at 200 degrees for 30 minutes, stir, and repeat. For large batches, spread the soil in a full-sun area, turning it every four weeks. After about eight weeks, it will be ready for use. The sun will kill bacteria and weed seeds just like the oven, but it takes longer.
How to Store Potting Soil
You can store potting soil in its original sealed bag, which keeps moisture and rodents out, but still allows for some airflow. If the bag is too small or doesn’t seal, transfer the soil into a plastic container with a couple of small holes on each side for ventilation. Store the containers or bags in a dry, cool, and shady spot, as warm areas can encourage weed sprouting if the soil hasn’t been sterilized.
Where to Find Potting Soil
Pre-made specialty potting soil is available at most home improvement stores, nurseries, and greenhouses. You can also order it online from gardening and specialty websites, though keep in mind that shipping costs can be high. Once the weather warms up, use your potting soil for outdoor planting or to re-pot your houseplants as needed.
