What is the Best Potting Soil for My Houseplant?

When you need to repot your plants, how can you tell which is the best potting soil for your houseplants? This article provides a complete guide to everything you need to know about soil for houseplants.
Your potting soil is one of the most important factors in the bloom quality, nutrient content, and overall health of your houseplants. Depending on what type of houseplant it is, your potting soil will vary in drainage, consistency, and retention. The right kind of potting soil for the plant at hand will vastly improve its growth.

How to Choose the Best Potting Soil for Your Houseplant

If you pair a plant with the wrong type of potting soil it will experience growth problems, decay, and rot consistently. If you find yourself adding a lot of soil nutrients and fertilizer to your potted plants to keep them alive, they are probably in the wrong type of potting soil.
Identify the needs of each individual houseplant to cultivate. The internet is a great resource for identifying your plant’s needs. Read up on your houseplants best potting soil type, watering needs, and [lighting requirements https://www.bloomspace.com.au/blogs/indoor-plants/houseplants-and-lighting].
When you buy a plant from a local store, sometime they come with a plastic tag with plant-care instructions. You can also find lot of plant care instructions here on our site.

image of soil and pots and indoor plants

Moisture Retention

Moisture is a key consideration for your potting soil mix. Some plants need ample moisture in the soil, and some do not. A tomato plant needs a lot more water than a cactus.
Succulents and other desert plants are great to cultivate indoors, and they need very little water. So, the best potting soil for cacti and succulents is a sandy, non-retentive soil mix. Whereas, a blueberry bush needs moisture retentive potting soil, as to keep the roots from dying.
Seedlings need a stronger medium for their roots to grab onto, as opposed to an adult plant. Often, the smaller the plant, the more moisture retention it needs. If you are planting indoor from seed, or seedling, use a highly retentive soil mix that includes vermiculite.

What are Perlite and Vermiculite?

Many gardeners alter their potting soils content to suit the moisture retention needs of their plants. Perlite and Vermiculite are the most common methods of altering the moisture retentiveness of soil. Both are extremely useful, inexpensive, and available at your local gardening store.

Perlite – Moisture Drainage

Perlite is odourless, lightweight, foam-like pebbles. It acts as spacers between the clumps of dirt, which thins out the soil. Gardeners add perlite to their potting soil to make it drain water more efficiently.
Perlite comes from volcanic glass, which is heated to extreme temperatures and exposed to water. The water causes the volcanic glass to expand into a puffy, hard foam-called perlite.
The perlite pebbles have many canyons and mountains on their surface. This allows oxygen to get trapped in the crevices, which aerates the roots.
Since perlite is a rock it sheds moisture and prevents over-saturation of your soil. Use perlite in your potting soil for aeration and drainage.
If you have heavy soil, perlite is the perfect ingredient. Mix equal parts perlite to the heavy soil in order to reduce the weight by half. This will substantially increase the volume of soil you have to plant with, as well.

Vermiculite – Moisture Retention

Vermiculite is, in essence, the opposite of perlite. Vermiculite is comprised of absorbent, sponge-like flakes of silicate materials. Like perlite, vermiculite mixes into your soil, but it does so to add moisture retention to the mix.
It raises the pH of soil through potassium, calcium and magnesium interactions. Thus, making your soil more alkaline.
Vermiculite is an ideal potting soil additive if you live in a hot, dry climate that gets little rain. If you have an indoor planter that is seeping too much water, add vermiculite to increase the moisture retention.
The tiny vermiculite flakes absorb three to four times their volume in water. This adds considerable weight to your pot, making it more difficult to move. And, too much vermiculite can trigger your roots to develop rot because of a lack of oxygen.
With perlite and vermiculite, you can adjust the moisture retention and root aeration of your soil to suit any indoor plant.

image of potted plant soil test with wood stick

Soil PH Level

If you keep native indoor plants they will have specific pH level requirements of the soil. Some soil for native plants needs a lower pH or more acidic soil. Some need soil with lower acidity and a higher pH content.
Most potting soil mixes come with a pH of 7.0. By raising the pH of your soil, you lower the acidity of the soil. The best way to raise the pH of your potting soil is by adding powdered lime or limestone, also called a base.
If you need to make the soil less acidic, or more alkaline, you must lower the pH of the soil. The easiest way to lower the pH of your potting soil is to add sulfur.
Another option is to use composted materials and bio-decay to decrease the pH of the soil, but this takes multiple seasons.

The Best Potting Soil Ingredients

The secret to growing beautiful plants is the quality of soil in which they grow. And, the best soil is always homemade. Making your own soil is much more economical than bagged soil when you buy the ingredients in bulk.
Plants need a mixture of elements to give the nutrients and conditions they need to grow. Each of the individual soil ingredients can foster plant life on its own, but the best potting soil incorporates proportions of…

Peat Moss

Peat moss grows bright green on patches of oversaturated soil. It is made of dead sphagnum moss and organic soil. Peat moss is very lightweight and provides an excellent source of water retention.
Peat moss retains up to twenty times the moisture than soil without. It provides rich nutrient for the soil, as well as a retentive medium for root stability. Nothing else in a soil mixture performs the task of retaining water as well as peat moss.

Compost / Fertiliser

All serious gardeners have their secret methods and recipes for mixing the perfect soil nutrient. The most common fertilisers are a cow or chicken manure compost. But, a little-known secret for the richest potting soil is mushroom compost.
Mushroom compost provides nitrogen-rich organic phytonutrients to plants and is available at a local garden centre. And, of course, the most important nutrients in your soil mixture is from kitchen compost.
If your plants seem to be running out of nutrients, try adding worm castings. For deep green, luscious plants, pack worm castings around the root bulb of a sprout before transplanting.

Humus

Humus is not a Mediterranean dish of blended chickpeas-it is the dark, packed clumps of decayed organic material in soil and on the woodland floor. It comprises organic materials that are rich in nitrogen.
Humus is important for the nutrient content and moisture retaining ability of your potting soil. If you are mixing soil with homemade kitchen compost you are adding humus.
If you don’t have your own compost you can use a mixture of manure and mushroom compost. You can, also, forage the woods for some natural, wild humus.

Sand

Sand is essential for the drainage and oxygenation of your soil. Without sand, stagnant water sits on the roots of your plants and causes root rot. Sand, also, contributes vital micronutrients and minerals to the soil.
If your potting soil is too water retentive, sand provides excellent drainage. But sand is not lightweight. Potted indoor plants are often better suited to perlite as a drainage medium.

Light Soil vs. Medium Soil vs. Heavy Soil

Just like Goldilocks, you have to find the soil weight that is just right for your plant. The weight of your soil is the result of its ingredient mixture.
Heavy soil is often the best value and highest in nutrient, however, it is the most troublesome for plant growth. Lightweight soil enables strong, abundant root growth, but it is less moisture retentive and often requires maintenance.
Light soil is fine for hanging plants, but the best potting soil for any houseplant is medium weight soil. When you bring home a plant that is potted in very lightweight soil, transplant it quickly, before the roots dry out.

Final Thoughts

The best soil for indoor houseplants is a medium weight soil with peat moss and organic compost base. Give your transplant a complete soak, until water begins to fall out the bottom of the pot. The average indoor plant in the best potting soil should get a soak one time every week.
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