There are countless premade potting mix options on the market, but have you ever thought about making your own mix? Not only is it possible, but it gives you the ability to design a mix for your specific crops and growing style. Don’t compromise, give your plants exactly what they need.

Why Make Your Own Potting Mix?

Generic store-bought potting soils can be budget-friendly but don’t always meet the unique needs of different crops. They often contain unnecessary additives, and many mixes do not provide adequate drainage and aeration for high-value crops or sensitive seedlings. While specialized seedling mixes are available, they are not always the most cost-effective option.

When buying a more specialized, high-quality potting mix, the price tends to go up. At a certain point, the economy of buying amendments and mixing your own soil becomes apparent. If you are making large batches of custom mixes, or you decide that you have a specific goal in mind that a generic premade potting mix is not meeting, creating your own mix becomes more attractive.

Benefits of Making a Custom Potting Mix

Making your own potting mix gives you control over its composition, cost, and sustainability. The key to success is balancing drainage, nutrients, and moisture to meet your plants' specific needs.

Understanding the Basics of Potting Soil Mixes

Beyond sustainability, it's important to understand the fundamentals of different potting mixes. Let's break down their key components and functions.

Soilless Mix vs. Soil-Based Mix

Nearly all potting mixes are going to be a soilless mix. That means the mix will contain NO soil. The reason for this is simply that contamination can lead to struggles that are avoidable in an indoor or controlled setting. 

A lot of work goes into controlling as much of a plant’s life indoors as possible, and things can get complicated quickly when bacteria, weed seeds, or pests are introduced. In an ideal growing environment with little competition, an infestation can cause irreparable harm seemingly overnight. 

Key Ingredients in Potting Mix

A good “all-purpose” mix that can support many plants during most stages of growth is 1 part perlite to 1 part vermiculite to 1 part coco coir (1:1:1). With potting mixes, we use measurements in parts. This enables you to easily change the volume as needed for different-sized batches while still keeping the ratio of ingredients exact. 

This mix has ample water holding capacity and will provide the drainage and aeration required for most plants under reasonable watering conditions (you can almost always over water!) These ingredients are available at virtually any garden center. 

Beginner-Friendly Seed Starting Mix Recipe

This versatile, easy-to-make mix supports many plants through most growth stages.

Ingredients

• 1 part perlite
• 1 part vermiculite
• 1 part coco coir

Supplies

• Large container or wheelbarrow
• Large scoop
• Trowel or small shovel – for turning and mixing materials
• Dust mask – for safety when handling fine particles like perlite 
• Spray bottle or watering can – to moisten the mix evenly as you go

Instructions

1. Measure out equal parts of perlite, vermiculite, and coco coir.

2. Mix thoroughly in a large container or wheelbarrow.

3. Use as needed for potting or seed starting.

This mix provides good water retention, drainage, and aeration. Adjust batch size by keeping the 1:1:1 ratio.

Customization for Specific Plants

A soil mix will need different ingredients depending on the needs of the crop. All crops need water and a certain amount of oxygen to the root zone. 

Striking the balance between the amount of water availability and oxygen can take some experience with a specific crop. It is an attainable goal for the home gardener and can become essential when growing at scale.

What do Seedlings Need?

Seedlings need good drainage and aeration to avoid rot, bacterial growth, and pests from attacking tiny and vulnerable seedlings while they are at the beginning stages of development. Seedlings can be taken out in a surprisingly short amount of time from a variety of attackers. Excessive moisture is one of the most common threats. 

For some seedlings, nutrition is not a big issue, as many starts will be planted out relatively quickly, and the fertility of your garden soil will be the star of the show. However, nutrition can be vital for plants grown in a potting mix or for those who spend more time waiting for the garden to be free of frost.

You can feed your seedlings a diluted liquid vegetative growth formula or a weak compost tea. Place your seedling trays in a 1020 tray with an inch of the mix and allow them to absorb for an hour. This will provide them with enough nutrition to keep growing beyond 4 weeks. 

What do Vegetables Need?

Vegetables can require a variety of soil mix qualities. The biggest difference from seedlings is that vegetables need a larger quantity and variety of nutrition at later stages of growth. If you are using your custom mix for veggies, add 1 part compost or worm castings to the mix above. This supports more developed growth and feeds vegetative plant development in addition to flowering and fruiting crops. 

What do Houseplants Need?

When established, houseplants generally prefer soil with more water-holding capacity. Homes tend to have drier conditions than greenhouses. Low humidity increases water needs, and reducing the frequency of watering inside a house is often desirable. Use a house plant specific fertilizer in your mix or add a small amount of worm castings (around half a part).

Related:  10 Must-Have Indoor House Plants for Gardeners and Plant Lovers

Additional Nutritional and pH Needs in Potting Soil

Slow-Release Fertilizers and Organic Amendments

Some mixes will require a slow-release source of fertilizer. There are controlled-release fertilizers that are pelleted and designed to release plant food over a very reliable amount of time based on temperature and irrigation frequency. Organic amendments can be slowly released, or even consistently broken down by bacterial life in the soil over a period of many months in a living soil mix. 

When a Potting Mix Does Not Require Added Nutrition

Not every potting mix requires nutrition. Some mixes are used with fertilizer added to the irrigation water, and the potting mix acts strictly as an inert home for the plant roots.

Managing pH Levels for Different Crops

You can lower pH by starting with components that have a lower pH, such as peat. This is desirable for plants that need an acidic environment. You can also use a sterile mix and add liquid fertilizers and acids to keep pH consistently low. You can also raise the pH by adding lime or oyster shells.

Learn more about testing pH levels in our article, How to Test Soil pH Before Planting—And Why You Should.

Cost Savings with Custom Soil Mixes

Another important reason people look to create their own potting mix is cost. Buying soil components in bulk allows you to create customized mixes at a lower cost than pre-mixed options. Although this requires more work, it is not difficult and can enable you to plant more for the same price or save money while learning a new skill. 

An operation can save some money by making its own potting mix if it is large enough to use more than a bag at a time but not to the scale of taking in more than a partial pallet of potting mix. A basic, affordable potting mix is generally a reasonable fit for many different crops. When you get into specific mixes, the volume is orders of magnitude larger before affordability comes back into focus. 

For operations large enough to require multiple pallets or truckloads of potting mix, purchasing a premade mix becomes more viable. At this scale, the mixing equipment needed to produce a consistent, high-quality mix in a timely fashion can cost as much as a greenhouse operation.

Reduce Environmental Impact

The environment can also come into play when choosing the ingredients of a potting mix. Peat moss is a finite resource, and as a very acidic substrate, peat supports rare ecosystems that thrive on that acidity. Peat bogs take thousands of years to form. That has led to bans in some countries, and alternatives have been sought and are being brought to the market. 

Peat moss remains an important ingredient in a potting mix when a low pH is required, but most plants want a neutral to slightly acidic mix. If peat is used for plants that do not require a low pH mix, the mix must be amended. Lime is used to amend acidic mixes for plants that are happier in a neutral or slightly acid potting mix.

Coco coir is a more sustainable alternative to peat, offering similar water retention properties without requiring additional amendments to maintain a neutral pH. As growers consider the environmental impact of their soil choices, exploring alternative ingredients can contribute to more sustainable growing practices. 

Drainage, Moisture Retention, and pH Balance

If plants require more drainage, add perlite, pumice, sand, or bark mulch. When plants require more moisture or need to hold moisture for a longer interval between waterings, an addition of vermiculite, coco coir, compost, or peat moss can make all the difference.

How to Test and Tweak Your Mix

Customizing Fertilizer in Your Soil Mix

If you require fertilizer in the mix, there are many options.  There are preformulated organic mixes, but you can also pick and choose individual amendments for a fertilizer mix that is more tailored to a specific crop. Not everyone will want to use the same mix, and adjusting to your habits and conditions is encouraged as you get the hang of it. 

If you are unsure what you need to add, test your soil. It is always good to know what your soil is lacking before you throw the kitchen sink of amendments at it. Also be sure to check out our video series Soil Testing (Everything You Need to Know).

Related: A Beginner's Guide to the Best Soil Amendments for Healthier Gardens

Adjusting for Water Retention and Drainage

Water more than you should? Add more perlite, rice hulls, or pumice. 

Don’t want to deal with watering so much? Decrease perlite or substitute for vermiculite! 

Dealing with top-heavy plants that blow over easily? Add sand for extra weight and improved drainage.

Experimentation and Adaptation

Experiment—it’s your container garden! Many nursery growers like to use pine bark mulch mixed with compost and/or peat for large container plants like trees and shrubs. This simple mix is economical for woody plants that require large containers or grow bags and usually includes a slow-release fertilizer.  Adjusting and testing your mix will ensure that it meets your plants’ needs while working efficiently within your growing system.

Advanced Techniques: Living Soil

For growers looking to take soil management to the next level, living soil offers a self-sustaining alternative to traditional mixes. Unlike standard soilless mixes, living soil contains active microbial life that helps nourish plants naturally. This approach requires careful management but can create a self-sustaining, nutrient-rich growing environment.

What is Living Soil?

Living soil is exactly that — alive. Proper storage and shipping are essential to maintaining its quality, making it harder for large retailers to offer consistently. Living soil is best purchased from a trusted garden center or managed in the home or garden. 

There are companies that sell pre-made living soil. Some of these mixes are good quality living soil mixes, and they tend to cost more than a premade soilless mix. Soilless mix can sit on the shelf longer in a warehouse or store because they generally do not have living components. The life in a living soil mix will die if it dries out too much.

It is also possible to create a “living soil” through composting, vermicomposting, adding organic amendments and monitoring for pests, and disease. This use and reuse of a living soil can be intimidating but it is something you can accomplish and may enjoy. After gaining experience, problems and inconsistencies are readily recognized and working with a living soil can be a fulfilling project.

Maintaining Soil Health

When using living soil, additions for structure will generally make up the lion’s share of ingredients. They may include pumice, rice hulls, perlite and/or vermiculite to keep the soil fluffy and breathable, not only for the plant roots, but also for fungi and bacteria that form beneficial communities in the soil. Pumice or decomposed granite is recommended because it will hold up longer than perlite. 

When using an inert soilless mix, the breakdown of perlite is less of a concern because it is not going to be used for a long-term to indefinite period. Perlite is still viable in a living soil, it just needs to be replenished more often than pumice. In a living soil the focus is caring for the beneficial communities living in the soil in order to feed the plants. These tiny organisms make nutrition more absorbable and available to plant roots.

Some elements, like greensand, are only available to plants when these communities break them down; others are simply more effectively taken up by the plants with the help of these communities.

Common Mistakes and How to Avoid Them

Suppose synthetic fertilizer is used or the living soil is allowed to dry out. In those cases, many of the fungal and bacterial communities will perish along with the benefits of a living soil. The same goes for chemical pest control. In a soilless mix, additions of beneficial insects, nematodes, fungal and bacterial cultures keep the pests at bay. 

This is not to say there will be no pests or that the mix will always be balanced. Nature tends to work toward a balance, whether or not it is something that is easily perceptible. When starting down the path of a living soil, it is important to take notice of what is happening with the mix. The mix will change over time, and knowing that nature is on your side is comforting, but there can still be imbalances. 

Recognizing and Managing Soil Imbalances

Generally, these imbalances stem from the human tendency to nurture more than needed: too much water, too much of one amendment or another. This happens to everyone at times, but who has not had issues with a pre-mixed soilless mix? Certain amendments take months to be not only depleted but even to be available to plants as they break down in the mix.

In a living soil this is wonderful; the amendments stay with the mix for quite some time, and adding small amounts ensures availability. In a soilless mix, however, amendments like greensand may not become available before plants are harvested (especially in an absence of beneficial soil life.) 

If not reusing this soilless potting mix in a living soil, container plants may never get the benefits of the greensand that is still paid for when buying a soilless mix! Rock phosphate is another amendment that is wonderful for rootzone health, but depending on its form, may not be available for plants to benefit fully during one grow cycle. 

Fertilization and Pest Control in Living Soil

Living soil generally requires only clean, non-chlorinated water at irrigation time. If there is a deficiency, fertilizer is applied either as a top dressing or in the form of compost tea. 

Compost Teas: A Natural Fertilization Method

Compost teas can be brewed in many ways and can even be used for foliar feeding. Some nutrients, such as calcium, are actually better absorbed as a foliar feed. Compost tea foliar feeding also helps to protect the plant from pests and diseases that are otherwise controlled with chemical means that would otherwise harm beneficial insects and soil biology when pesticides drip off leaves and onto the soil’s surface. 

The key to using living soil is always looking out for beneficial bugs, microbes, and fungi! It can take some relearning control of certain garden pests, but it IS obtainable and can be extremely rewarding to see every aspect of the garden work together in harmony. 

FAQs about Making Your Own Potting Mix

What are the best ingredients for a homemade potting mix?

The best ingredients for a homemade potting mix are ingredients that are available locally and sustainably. Coco coir, pumice, decomposed granite, compost, worm castings and perlite are the most common. 

This article from Penn State Extension gives some other good recipes and ingredients.   

Can I make a potting mix without peat moss?

Yes, potting mixes can be made without peat moss. It could even be said that a potting mix should not include peat moss unless the plants to be grown in the mix require an acidic mix or you cannot find a reasonable source of coco coir. With the increased availability of coco coir and the proliferation of internet shopping, one could argue the necessity for peat moss should be quite rare for most growers.

How long does homemade potting soil last?

Homemade potting soil, if an inert mix of pH-neutral ingredients is used, has an unlimited shelf life. However, some soil ingredients, such as peat moss and, to a lesser extent, coco coir, can become hydrophobic when dry and require thorough soaking to rehydrate. 

Some mixes, including peat moss, may experience a drop in pH over time and should be tested to ensure there is no need for lime to bring the pH to a tolerable level. Coco coir based mixes do not change pH from sitting, but some organic fertilizers can be depleted. 

Living soil needs to be used, composted, and managed. If living soil is allowed to dry out, the soil life dies, and when the soil life dies, the soil is no longer living. In this case, the soil needs new compost, and bacterial and fungal cultures and it may take some time to return to its full fertility.

What’s the difference between potting mix and garden soil?

Potting mix is the way to go when growing plants in containers. Garden soil and soil mixes are commonly used to amend in-ground plants. Soils are heavier and have smaller particles. A good way to feel the difference is to lift a bag of potting mix and a bag of soil of a similar volume. The soil is much heavier because there is less pore space. Smaller particles without pore space make for a denser substrate, while soil can hold water fairly well, it does not have as much space for air. Oxygen is vital for healthy, white, fast-growing roots.

Some containers, such as grow bags and other root pruning containers, can handle topsoil “better,” but at the very least, it should be amended with a material to improve drainage and increase aeration in the root zone to maximize their beneficial qualities. Amendments for better drainage and a breath of fresh air for roots include perlite, pumice or decomposed granite, vermiculite, and sand if added weight is desired.

Can I make potting mix from compost alone?

Compost is not a complete mix. In order to provide plants with proper conditions compost needs other components to make a potting mix capable of supporting a plant's full potential. 

How can I tell if my potting mix drains properly?

After watering and allowing time for water to run through the mix, take a big handful and squeeze it. When squeezed, there may be a few drops of water, but water should not run out of the handful of mix.

Written by Andy Russo, Russo Tree Farm