How to Mix Potting Soil (FULLY EXPLAINED)

If you enjoy growing things or even just having plants around that look pretty and green, learning the proper way to mix potting soil for various species is crucial.

But, before you can do that, you need to know more about the nature of potting soil in general.

What is potting soil made of? Potting soil is typically made of three ingredients: peat moss, topsoil, and perlite. Sometimes it is made from mature compost in place of peat moss, loam in place of topsoil, and sand instead of perlite. Other ingredients such as pebbles, mulch, and other organic matter may be mixed into potting soil before planting.

Read on below to discover everything you need to know about how to mix potting soil!

How to Mix “Regular” Potting Soil

Generally speaking, mixing potting soil is quick and easy. In fact, many mixes are good to go right out of the bag, if you prefer to purchase it rather than make it yourself.

That said, while a vast majority of garden variety plants, including many of your favorite vegetables, herbs, and indoor houseplants sprout and grow just fine in basic potting mixes, some plants take special preparations.

A little bit further on in this article, we discuss the differences in the best potting soil mixes for the main varieties of plants, including indoor/outdoor, trees, flowers, succulents, cactus, and Bonsai trees.

But, for now, let’s have a look at the steps for mixing generic potting soil:

1. Prepare Proper Containers and Ingredients

The first step to mixing potting soil is deciding what size containers you need. If you’re mixing soil to pot a few plants for the home or garden, you don’t need very large containers.

If you’re mixing potting soil for commercial purposes, you need to gather several 5 to 10-gallon containers as well as a much larger one for the final product.

2. Begin Mixing Ingredients Together

Whether you’re using old milk jugs with their tops cut off, or 50-gallon barrels, start off by mixing your mature compost or peat moss into the topsoil or loam.

Make sure to mix the ingredients well; stirring, shaking, and/or tossing the contents of your containers vigorously.

3. Add Water

Once you’ve got the two main ingredients of your potting soil mixed together, it’s time to add some water. Whether you use a water can, a sprayer, or the garden hose is up to you.

Water the mixture until it is darker in color but is still workable.

Whatever you do, try to avoid turning it into dirt soup by adding an excessive amount of water. If it’s overwatered you’ll need to add a bunch more ingredients to make things right.

4. Continue Mixing Ingredients

Continue mixing in the ingredients you’ve selected for your potting soil, including perlite and/or sand.

You save these ingredients for last because they change the consistency of the mixture the most. So, add them slowly and in carefully measured amounts.

Note: If you aren’t planning on using the potting soil for ordinary plants, skip on down to the appropriate section of the article that explains what to do for the type of plant you’re potting.

5. Give Your Potting Soil the Squeeze Test

For normal potting soil mixtures, you know you’re done with it passes the squeeze test.

That means when you take a fist full of the soil into the palm of your hand and squeeze, the soil stays together when you release it.

If the soil crumbles, it is likely too loamy. On the other hand, if it is sticking to your hands the mixture is holding too much moisture and needs more ingredients.

Mixing Soilless Peat-Based “Potting Soil”

Soilless peat-based potting soil is made of alternative growing mediums mixed together. The main ingredients found in soilless potting mixes include:

• Sphagnum peat moss
• Perlite
• Vermiculite
• LECA
• Lava Rocks

The basic recipe for soilless peat-based potting “soil” is 1/2 peat moss and 1/2 perlite (or 1/4 perlite and 1/4 vermiculite). Follow the same instructions from the “How To” section above for mixing a soilless potting soil.

Why the Best Ingredients for Potting Soil Differs From Plant to Plant

The growing medium that plants grow in does more than just anchor and protect roots, the growing medium also provides the majority of the nutrients needed for the plants to develop properly and thrive.

Yes, that means that your plant’s health is directly related to the growing medium that you use. Further, that’s why you should learn exactly what type of soil or growing medium benefits the type of plants you’re growing!

A few points to consider about typical soil mixes:

• Mixes with clay are stiff and don’t retain much water
• Sandy soil is fast draining but doesn’t hold nutrients as well as other soil mixes
• Loamy soil mixes are all-around the most fertile and water-retaining potting mix
• The type of soil you use anchors your plants feeds them and waters them

So you see, the potting mix you choose makes a world of difference to your plants, in many more ways than one.

Potting Soil for Indoors Plants

The best potting soil for indoor plants is typically heavy in peat, coco-coir, perlite, and/or vermiculite. Like this Miracle-Gro Houseplant Potting Mix.

Can you use regular potting soil for indoor plants?

Regular potting soil isn’t as highly recommended for indoor plants as it is for outdoor plants but may work in a pinch. Try a mix with coco-coir, peat, or perlite.

Potting Soil for Outdoor Plants

Outdoor plants come in a wide variety, though most of them do just fine in regular potting soil (like the recipe we shared at the beginning of the article). If you prefer to buy one, we suggest trying this Burpee Organic Potting Soil Mix.

Can you use regular potting soil for outdoor plants?

Outdoor plants need rich potting soil with lots of organic materials (more so than indoor plants) because they are constantly exposed to the elements. The Burpee organic mix above is perfect for gardens and containers.

Potting Soil for Flowers

The best potting soil for flowers is much lighter and fluffier than standard indoor or outdoor potting soil mixes. The main difference is that they include everything from tree bark to worm castings and higher percentages of peat or coco coir than other mixes. Harris’s Orchid Potting Mix is a great example.

Can you use regular potting soil for flowers?

Most flowers will grow in a regular potting mix, but they won’t thrive. Further, more delicate flowers, like Orchids and African Violets may not grow at all in normal soil. That’s why you need a potting mix like Harris’s.

text.While the basic peat moss, pine bark and perlite type potting mixes will work fine for almost all annual flowers and mixed potted plants, there are some crops for which specialty mixes might be helpful.

Potting Soil for Trees

The best potting soil for trees depends on the species of tree, as many prefer loamy soil made of peat moss and vermiculite or perlite. However, some trees prefer sandy or alkaline soil. That’s why you need to know your tree species before you mix soil or plant them. We suggest giving something like Wonder Soil Premium Organic Potting Soil Mix a try if you don’t want to mix your own.

Can you use regular potting soil for trees?

Trees do best with native soil with at least 1/4 or 1/3 of the backfill mixed with organic compost (or an organic potting mix like Wonder Soil). In containers, avoid native soil and go straight for a rich and organic mix instead.

Potting Soil for Succulents and Cacti

Succulents and Cacti thrive from the same sort of potting mixes; soil with sand, pebbles, pumice, or perlite. The mixture should be approximately 2 parts sand and gravel, 2 parts soil, and 1 part perlite (or pumice), like the Premium Cacti and Succulent Potting Mix Soil from Fat Plants San Diego.

Can you use regular potting soil for cactus and succulents?

Regular potting soil is not recommended for cactus or succulents because if cactus or succulents get too wet, they rot. A standard potting soil mix may work, but you’ll need to spend a lot more time catering to your plants and checking on their moisture levels.

Potting Soil for Bonsai Trees

The best potting soil mixes for Bonsai trees often include lava rock, gravel, sand, pumice, organic compost, and Akadama. Further, they should be pH-neutral, not basic, and not acidic either. This Generic Bonsai Potting Soil is the perfect all-purpose soil, no matter what species your Bonsai is.

Can you use regular potting soil for bonsai trees?

It is absolutely useless to plant Bonsai trees in regular potting soil. Bonsai need neutral soil, with lots of sand, gravel, and other porous growing mediums, as well as a bit of moss, like the Generic Bonsai mix above.

FAQs

How do you mix potting soil for indoor plants?

The easiest way to mix potting soil for indoor plants is to purchase something pre-mixed. That said, mixing it yourself isn’t too hard (scroll up to the top of the page and read our “How To Mix Regular Potting Soil” section! More or less, mix two parts peat moss or coco coir with 1 part pumice or perlite, and 1/2 to 1/4 part vermiculite.

Do I need to mix anything to potting soil?

Potting soil absolutely needs additional ingredients mixed into it, unless you are growing something extremely basic that requires very few essential nutrients. Once you’ve mixed in peat moss, perlite, bark, pumice, or other organic materials, potting soil becomes rich and organic potting mix.

Can you plant in just potting mix?

Potting mix is made ready for use without additional mixing (unlike potting soil). Ideally, potting mixes are lighter than soil, have better water retention and quicker drainage, as well as provide most of the essential nutrients your plants need to grow and thrive.

A Final Word About Mixing Potting Soil the Right Way (For You!)

The best potting soil for your plants depends on the species of plant, the environment they are growing in, how much work you’re willing to put in and much more. Hopefully, our in-depth guide to mixing potting soil helps you choose the right one for you and your plants, as well as teaches you how to mix it properly!

Thanks for reading!

Do you have a favorite potting soil mix that you’d like to share with our audience? If so, drop us a line in the comments section below… and don’t forget to tell us what sort of plants you grow with it!

Suggested Reading: What is the Difference Between Much and Compost?