By: Audrey Stowe Smith | Published 10:15 AM, June 23, 2021

The soil for growing flowers and food is an important part of the success of the garden. If you only need a small amount of soil to fill a few containers, it may be the most economical for you to buy a bag of mixture instead of DIY potting soil. However, if you need a large amount, you can sometimes save money by buying the ingredients separately and combining them yourself.

Most mixtures include moisturizing ingredients and ingredients that promote good drainage, usually in equal amounts. This helps to create a balanced soil that will remain moist-but not soaked-for a while after watering. Some people may also add fertilizer and lime to sweeten the pot.

Related: What's the difference? Garden soil and potting soil

Although peat moss has long been a standard ingredient in potting mixes because it can keep the mix moist, it is not the only substance suitable for this purpose. If you have environmental concerns about the depletion of peat bogs, you can substitute coconut husks (purchased from coconut husks) or compost.

Remember that although peat moss retains moisture well once it is wet, it is difficult to wet when it is completely dry, unless a wetting agent is added in advance. If your moss does not contain such agents, put a few drops of detergent in each gallon of water used to moisten the moss, and add soap after the water runs out to avoid foaming. (Each 3 cubic feet of peat moss requires approximately 20 gallons of water.) When using mixed ingredients, be sure to wear a dust mask to avoid inhalation of fine particles.

If you use sand for this purpose, you will need to make coarse sand, because other types of sand may be too dense to provide sufficient aeration for the soil. Alternatives to sand include perlite (heated volcanic rock) and vermiculite (heated mica).

Please remember that compared with finer grades of perlite and vermiculite, coarse grades of perlite and vermiculite have faster drainage and less water retention, although generally vermiculite retains more water and nutrients than perlite. This may be a good thing, or it may not be a good thing. Therefore, vermiculite is most suitable for plants that prefer continuous moist conditions, while perlite is more suitable for plants that prefer dry soil.

Or, as suggested in The Old Farmer's Almanac recipe, you may want to use equal amounts of perlite and vermiculite as moisturizing ingredients. In recent years, some gardeners have replaced perlite with loose flakes.

The disadvantage of sand is that it is heavy, about 80 to 100 pounds per cubic foot when dry. Therefore, if you use sand that accounts for more than 10% of the mixture, the potting mixture containing it may be unacceptably heavy. Of course, when you pot plants that tend to be top-heavy and need a stable base, a slight increase in weight may be a good thing.

However, if you want to save heavy work, choose perlite (6 to 8 pounds per cubic foot) or vermiculite (5 to 8 pounds per cubic foot), both of which are much lighter than sand and provide good The same benefits of ventilation and drainage.

You can mix a moisturizing ingredient with an ingredient that promotes good drainage (such as equal amounts of peat moss and perlite) to make a simple soil-free mixture. However, if you prefer to add garden soil, you need to purchase designated sterilized bags of commercial varieties. This will protect your potted plants from any diseased spores, insect eggs or weed seeds that might lurch in the soil taken directly from your garden.

The disinfection of garden soil requires heating it to 200 degrees, which is a process that you may not want to cause odor to your family. The Penn State University potting soil formula recommends that you mix bagged garden soil with equal amounts of peat moss and perlite to ensure it is light enough for potting, recycling containers, and vertical gardens.

Related: Everything you need to know about fertile soil

If peat moss with a pH of about 4.5 makes up the majority of the potting mix, the mix may be too acidic. Planet Natural recommends adding 10 pounds of limestone to every cubic yard of peat moss or coir/perlite mixture. However, when using coir fiber, you may be able to reduce or eliminate limestone because it is less acidic than peat moss.

If you want to add fertilizer, the formula recommends adding 20 pounds of bone meal and 10 pounds of blood meal to the cubic yard of mixture. Or, according to the aforementioned Farmer's Almanac formula, you can mix 2 cups of time-release fertilizer granules into approximately every 6 ½ gallons of the mixture.

Related: How to: Test Soil pH

If your mixture looks lumpy when finished, use a ¼-inch or ½-inch mesh hardware cloth as a sieve and press the soil through it to break up the clumps. This usually works best if you nail the hardware cloth to a wooden frame and place the frame on a wheelbarrow or storage container.

As with bread recipes, if your mixture looks too sticky or too dry, you may need to adjust the ingredients. For "too sticky", add more ingredients that promote drainage, and add more moisturizing ingredients "too dry". Once the mix is ​​just right, store it in an airtight plastic trash can to keep it moist.

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