Making Potting Soil Mix: Three Tips

A double handful of potting soil.

Potting soil mix is usually used for container plants, window boxes, small planting beds and special-needs plants. Commercial potting mix can be great, but the cost quickly adds up. Many gardeners choose to make their own potting soil because of this and also to control its ingredients. Below are some tips for making a good potting soil mix, as well as some recipes.

Manage Drainage and Nutrients

A good potting soil mix has the following characteristics: it drains well and easily, contains organic nutrients, retains water, is light and fluffy-not too compacted, and has particles or materials that improve aeration. Make sure the ingredients you use provide these qualities to maximize the growing environment.

TIP: Both sand and perlite act as great drainage additives. Sand is much heavier so use it if you need to weigh down a lightweight container in windy conditions.

Use a Mix of Ingredients

Use a combination of ingredients. Many recipes for potting mix include peat moss. Peat moss certainly contains a lot of nutrients that are great for your plants, as well as having a texture that aides in drainage and prevents compaction. However, recent studies show that the harvest of peat moss actually destroys the wetlands where it is found. Now, many gardenes choose to leave out this component to help save these wetlands. The choice whether or not to use peat moss is yours.

TIP: Coconut coir, also known as coco peat, is a nutrient-packed peat moss substitute. It has amazing water holding capacity and reduces frequent watering in addition to providing excellent drainage. It can be bought as a brick or bale, or pre-hydrated. In brick or bale form the coir needs to be hydrated by submerging it in water until it is fully saturated. It will grow to roughly five times its original size. Fluff by hand to separate the fibers and you are ready to go! You can buy coconut coir at some garden supply stores or order it online.

Using compost and organic matter is always a great way to make potting mix. Homemade compost is nutrient-packed and certainly cheaper. However, store bought works just fine. Leaf mold, hummus, vermiculite (worm compost), and aged manure are other effective nutrient-rich options.

Ingredients that help potting mix to be well-drained and fluffy are perlite, coconut coir, pumice, and sand. These are all great additives for potting mix.

TIP: Even if you make a well-draining potting mix, you should still include drainage implements when planting. Place small rocks or broken up pottery in the bottom of your container before filling with potting soil.

Avoid Plant Diseases and Weed Seeds

When combining ingredients for your potting soil mix, make sure everything is clean and sterile to avoid plant diseases, bad bugs and weed seeds in your mix. If you do use garden soil, make sure it is sterilized. Mix and store your potting soil in clean sealable buckets or new resealable plastic bags and use clean tools. Your old tools can be cleansed by wiping them down with a bleach soaked rag, and rinsing clean. Wear gloves when mixing. Before planting with your mix, make sure all plant containers are clean. To clean pots and buckets, wash with soap and water, rinse, and spray with bleach diluted with water. Towel or air dry.

A Basic Recipe

TIP: Customize your potting soil ingredients depending on what plants you want to grow. For example, camellias and rhododendrons like an acidic soil while garden clematis and lilac prefer the alkaline end of the range.

1 part compost (or 1/2 part compost 1/2 part aged manure)

1 part coconut coir

1 part pumice or perlite

1 part sand

Hydrate your coconut coir and fluff it by hand. Add all other ingredients, mix thoroughly, and viola!

You can use sand or soil that you find in nature so long as you take care to sterilize it first. Sift the material through a 1/4 inch sieve. Spread it on a large cookie sheet and cover with aluminum foil. Bake at 200 degrees F for 30 minutes, mixing occasionally.

A Soil-Less Recipe

Some plants require soil-less potting mixes, such as bromiliads and some orchids. A simple soiless mix recipe is below.

8 quarts coconut coir (or peat moss)

1 quart perlite

1 quart vermiculite

Hydrate coir (if using) and mix all ingredients thoroughly.