Soil & Repotting Mastery: Your Complete Guide to Thriving Houseplants

The Garden Soil Myth: Why Indoors Are No-Go?

Ever found yourself wondering why a houseplant isn’t flourishing? Although the leaves are still drooping, or perhaps not growing as vigorously as you would have expected, you water it regularly, and it gets plenty of light. Usually, the secret lies in the soil beneath the surface. Many new plant parents mistake soil for simple “dirt,” an inert material meant to hold the plant in place. Actually, though, the foundation of your houseplant’s health is soil—a sophisticated ecosystem that supplies air, water, and nutrients to the roots. Choosing the right soil is not just a personal preference, but also a critical decision that can significantly impact the success of your plant.

This page will help you go through the sometimes bewildering realm of potting mixes. We will dispel common misconceptions, including the belief that indoor use of garden soil is appropriate. From peat moss and coco coir to perlite and vermiculite, we will explore the main components that comprise various potting mixes and discuss their purposes in providing the best conditions for the roots of your plants. With their own particular requirements, you will learn how to match the appropriate soil type to particular plant categories, including succulents, African violets, and orchids. We will lastly discuss the fundamentals of repotting, a vital habit for preserving long-term plant condition. From the general relevance, let us explore particular kinds of soil.

Can I Use Garden Soil for Houseplants?

Assuming garden soil is suitable for houseplants is a common mistake made by novice plant owners. Plants grow outside after all; why not indoors? The simple but important response is that the conditions in a container are quite different from those in a garden bed. Almost always, bringing garden soil indoors results in disaster.

A big issue for containerized plants is compaction. In the open ground, soil is constantly being aerated by worms, insects, and natural weathering events. Garden soil, however, compacts over time in a pot to create a dense, solid mass. This compaction reduces airflow to the roots, depriving them of the oxygen they require to operate as they should.

Moreover, this causes significant difficulties. Poor drainage is a direct result of soil compaction. The pot retains water, leading to a soggy and oxygen-starved environment. This also leads to root rot, a common cause of death for houseplants in garden soil. The fungal disease known as root rot essentially suffocates the plant from below by thriving in wet, anaerobic conditions.

Beyond compaction and drainage, unwelcome guests present a problem. Garden soil can harbor pests and diseases (common ones) that would be quite unwelcome in your indoor environment. These could all wreak havoc on your houseplants: insect larvae, fungal spores, or perhaps weed seeds. You are essentially importing a bit of the outdoors with all its possible drawbacks.

At last there is a nutritional mismatch. Specific nutrient requirements of houseplants often exceed those of garden soil. Garden soil’s nutrient composition depends on its location and history; it might be lacking in some elements necessary for good houseplant development. Potting mixes, on the other hand, are designed especially to offer a harmonic combination of nutrients.

A pot’s regulated environment calls for a different strategy than a garden bed. While garden soil would be ideal for outside use, its natural qualities make it inappropriate for the limited, manmade space of a container. A specialized potting mix is essential for providing the drainage, aeration, and nutrients houseplants need to flourish.

Comparing garden soil vs. potting mix

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Common Myths vs. Facts

We’ve already discussed why garden soil isn’t perfect for houseplants, but let’s directly address some often held misconceptions. Knowing these myths will help you avoid possibly fatal errors for your indoor plants.

Myth 1: Garden soil must be better since it is “natural.”

• Fact: Garden soil is unnatural in the small space of a pot even if it is natural in an outdoor environment. Given the great variations in conditions, the “natural” case falls apart. Outdoors, natural processes including earthworm activity and rainfall patterns support soil structure and drainage. These processes are absent in a pot, which results in the discussed issues: compaction, inadequate drainage, and nutrient imbalances.

Myth 2: Garden soil is less expensive; thus, it’s a good approach to save money.

• Fact: Although garden soil itself might be free (should you have a garden), using it could result in far more expenses. Dealing with pest infestations, replacing dead or struggling plants, and purchasing specialized treatments to fix issues much exceed the initial savings. One preventative action that saves money over time is buying a quality potting mix—always easier than reviving a plant.

Myth 3: Basically all soil is the same.

• Fact: This represents a basic misinterpretation. Potting mixes and garden soil have quite different compositions and uses. Garden soil is primarily mineral-based (sand, silt, clay), while potting mixes are soilless blends intended especially for container drainage and aeration. Imagine it as though you were comparing a light, airy sponge to a dense, heavy clay brick.

Myth 4: I can simply make garden soil appropriate by adding some fertilizer.

• Fact: Fertilizer fills in nutrient shortages; it does not fix structural problems with garden soil in containers. Fertilizer added to compacted, poorly draining soil is like bandaging a broken leg; it doesn’t solve the fundamental problem. If the roots are suffocating, the plant will still not be able to efficiently access the nutrients.

Myth 5: My houseplants will also do great in garden soil since my outdoor plants do.

• Fact: Outdoor plants have evolved to fit the particular soil type in your garden. They are subjected to natural rainfall and drainage patterns; they have developed root systems capable of spreading outside their current vicinity. Especially those from different climates, houseplants are limited to the small area of a pot and are not suited for your garden soil.

Myth 6: Any issue will be resolved by oven sterilizing the garden soil.

• Fact: Although it will not solve issues including compaction and drainage, sterilizing can help kill bacteria. It will also kill any beneficial bacteria, rendering the soil dead for your plants.

In essence, even if using easily accessible garden soil would seem appealing, the truth is that houseplants almost always suffer from it. To give your indoor plants the best opportunity of survival, stick to specially made potting mixes.

Exceptions: When Might Garden Soil Be Used, and How to Sterilize (with Caution)?

Although we highly advise against using garden soil for most houseplants, there are very few situations where it might be considered, and even then, only with major changes and care. This section discusses last-resort options and the associated risks, not advocating for the use of garden soil.

When Might Garden Soil Be Considered (and Why Is It Still Risky)?

• For very large outdoor containers (think of half-barrels or big raised beds used as planters), the sheer volume of soil required can make using only potting mix cost-prohibitive. Even here, a good amount of the mix—at least half—should still be changed with potting mix ingredients like perlite, coco coir, and compost. Though compaction is still a problem, the larger volume offers slightly better drainage and aeration than a small pot.
• If you are planting native plants in a very large container outdoors and they are particularly suited to your local garden soil, you may be able to use a highly modified form of your garden soil. Given differing container conditions, this remains dangerous.
• If you absolutely have to use garden soil for a very brief period (e.g., temporarily potting a seedling before transplanting it outdoors), you can, but it’s not ideal.

Important Caveats—even in These Exceptions:

• Garden soil needs to be heavily modified using materials including compost, perlite, vermiculite, and coco coir or peat moss even in the above conditions. The result is a much thinner, airier, better-draining mix. Starting with a 1:1:1 ratio of garden soil, compost, and perlite/vermiculite will help you greatly.
• First priority is drainage: Verify the container’s drainage quality. This can call for adding more drainage holes or a layer of gravel at the bottom—though the efficacy of the gravel layer is hotly contested.
• Key is observation. Look closely at the plant for indicators of stress, including yellowing leaves, slow development, or wilting. Should issues surface, be ready to repot using a suitable potting mix.

Sanitizing Garden Soil: If absolutely necessary

While sterilizing garden soil eliminates both beneficial and harmful germs, it fails to tackle fundamental problems such as compaction and drainage. Not a solution; this is a last resort.

Techniques with disadvantages:

• Oven Strategy:
  
  • Turn oven to 180–200°F (82–93°C).
  • On a baking sheet, thinly layer moist—not soaking wet—garden soil no more than 4 inches deep.
  • Bake till the soil temperature reaches 180°F (82°C), at least 30 minutes. Check with a soil thermometer.
  • Before use, let the ground cool totally.
  • Drawbacks: It generates a strong, disagreeable smell. can cause the soil’s structure to deteriorate even more. kills important bacteria.
• Microwave Approach:
  
  • Place moist garden soil in a microwave-safe container (without a lid or with ventilation holes).
  • Stir in between; microwave on high in short bursts (one to two minutes) until the soil is steaming.
  • Let the ground cool totally before using.
  • Drawbacks: Less efficient for big soil amounts. Might be unequal; kills useful bacteria.
• Solarization, summer only
  
  • Put moist soil in the black plastic bags.
  • Under direct sunlight, arrange the bags.
  • Turn bags consistently.
  • Check internal temp with a soil thermometer. You want at least 160 degrees F (71 C) for at least 30 min.
  • Drawbacks: Relies on consistent sunlight and high temperatures. Kills beneficial microbes.
• The steam method is Using a pressure cooker or specialized soil steamer is the most effective method, but it requires specialized equipment.
  

After Sterilizing:

• Reintroduce Beneficial Microbes: Consider adding a compost tea or a commercially available microbial inoculant to the sterilized soil to help re-establish a healthy soil ecosystem. This is not a perfect solution, but it can help.
• Amend heavily. As mentioned before.

In conclusion, while there are very limited situations where heavily amended and (possibly) sterilized garden soil might be used, it’s almost always better to choose a high-quality potting mix designed for container plants. The risks and extra work associated with garden soil generally outweigh any potential benefits.

What’s the Best Soil for Houseplants?

After we’ve determined why garden soil isn’t fit for houseplants, let’s investigate potting mixes as the better substitute. Most commercially sold potting mixes are really soilless, which is something to know. Particularly designed for the special requirements of container plants, potting mixes offer the correct ratio of aeration, drainage, and nutrient retention. Designed combinations of several ingredients, each with a particular use, they are

Let’s deconstruct some of the main components in most potting mixes:

• Peat Moss:
  
  Harvested from bogs, partially broken down plant matter is peat moss. Its great water-holding capacity makes this a common component in many potting mixes. It keeps moisture well, which helps many plants avoid drying out too rapidly. Peat bogs are important ecosystems; thus, there are growing questions regarding the viability of peat moss collecting. Environmental issues make one consider alternatives free of peat.
  
• Coco Coir:
  
  Made from coconut husks—a byproduct of the coconut business—coco coir is This qualifies this as a more sustainable substitute for peat moss. For potting mixes, this renewable resource has great qualities. It has great water retention, much as peat moss does, but it also often has better aeration qualities. Though with less of an environmental impact, coconut coir has same advantages as peat moss. As the main ingredient in potting mixes, it is growing rather popular.
  
• Perlite:
  
  Though it is actually heated and expanded volcanic glass, perlite resembles tiny white Styrofoam balls. Every particle has innumerable small air pockets produced by this process. It generates necessary air pockets in the ground, improving drainage and avoiding compaction. Consider it as including tiny air pockets all around the potting mix to let roots breathe naturally.
  
• Vermiculite:
  
  Like perlite, vermiculite is a naturally occurring mineral that expands under heat, but its structure is different. It excels at keeping nutrients and has a more plate-like form. It releases nutrients and water gradually to the plant roots as needed, so helping to preserve both. Which mix—perlite or vermiculite—should you thus decide upon? Vermiculite is better for moisture retention; perlite is better for drainage. If you have plants prone to root rot, a combination including more perlite is better. Vermiculite is a better option for plants that want always moist soil.
  
• Compost:
  
  Comprising broken-down organic materials including leaves, food waste, and yard trash, compost is nature’s fertilizer. It enhances soil texture and supplies important minerals. It enhances the potting mix with a slow-release nutritional source, encouraging good plant development. Still, you should use just well-composted materials. Steer clear of unfinished compost since the continuous breakdown process can introduce pathogens or “burning” roots that would damage plants.
  
• Bark (from Pine Bark Fines):
  
  Usually from pine trees, small bits of bark make up bark fines. These are frequently used in mixes for plants like some succulents and orchids that call for outstanding drainage. Plants that require great drainage must pay close attention since the larger particle size generates big air spaces in the mix.
  
• Extra Notes:
  
  • Sand is used in some specialized mixes to boost drainage even more.
  • Castings from worms are organic fertilizer.

Comparison Table: Potting Mix Ingredients, Purpose, and Best Uses

Guide by Plant Type: The Correct Mix for the Correct Plant

Though knowing the elements of potting mixes is important, the real secret is knowing how to mix them to satisfy the particular requirements of various plants. Selecting the appropriate potting mix is like selecting the proper meal for your plant; various plants have different dietary needs. You shouldn’t use the same soil; just as you wouldn’t feed a cactus the same diet as a fern.

The following is a guide for selecting the appropriate mix for several typical houseplant varieties:

• General Houseplants (such as peace lilies, spider plants, and pothos):
  
  Generally speaking, these common houseplants would fit a balanced, all-purpose potting mix. Usually featuring peat moss or coco coir, perlite, and vermiculite, these mixes offer a good balance of drainage and water retention. Key traits: Look for a mix that offers enough moisture retention and good drainage, combining peat moss or coco-coir, perlite, and vermiculite. This guarantees that the soil neither stays overly wet nor dries out too rapidly.
  
• Succulents and Cactus:
  
  A fast-draining mix is absolutely crucial since these plants require soil that dries out quickly. Create your own by adding extra perlite or coarse sand to a general-purpose mix; search for mixes especially labeled for succulents and cacti. Essential traits: Preventing root rot, a common issue with succulents and cacti in too moist soil, depends first on great drainage. Think of desert conditions: These plants require a soil that replicates their arid surroundings since they are suited to such conditions. One approach to increase drainage is adding sand.
  
• African Violets:
  
  African violets prefer a slightly acidic environment; thus, a mix including more peat moss (or a peat-free alternative intended for acidic conditions) is usually advised. Main Features: Excellent retention of moisture, somewhat acidic pH. Though not soggy, the ground should always remain moist.
  
• Orchids:
  
  A very coarse, bark-based mix is best since orchid roots require lots of air movement. Usually with added perlite or charcoal, these mixes feature big bits of bark and very little to no peat moss. Essential for orchid health are outstanding drainage and airflow to the roots. Mirror their natural epiphytic habitat: Many orchids grow on trees in their natural habitat; their roots are air-exposed.
  
• Azaleas and Camellias: Acid-Loving Plants
  
  Suggested Mix: Peat-based, maybe including sulfur. These mixes are designed to have a reduced pH, which these plants need for the best absorption of nutrients.
  
  Should keep a pH ranging from 5.5 to 6.0. For these plants, routinely testing the soil pH and adjusting as necessary is vital.
  

Important Note: Always investigate your plant variety’s particular requirements. These are broad rules; some particular species or cultivars may have rather different needs. Always a smart idea is to consult specific resources for your particular plant.

Best Potting Mix for Each Type of Houseplant

The Right Way to Repot Your Houseplants

A key component of houseplant care, repotting offers fresh nutrients, better drainage, and space for development. Correct application of it will greatly affect the health and lifetime of your plant. Covering when to repot, selecting the correct pot, the repotting process itself, and common mistakes to avoid, this section dissects the process into simple, easily followed steps.

When should one repot? (Aware of the Signs)

Look for these obvious indicators that your plant needs a new home instead of repotting on a set calendar:

1. Root-bound is the most obvious indication. Slide the plant gently out of its pot (or check through the drainage holes). The plant is root-bound and requires more room, whether the roots are circling the bottom of the pot in a dense mass or emerging from the drainage holes.
2. If your plant’s growth has greatly slowed down or stopped completely despite enough light, water, and fertilizer, it may be root-bound or the soil may be nutrient-starved.
3. Watering Concerns:
   • The soil is probably compacted and hydrophobic—that is, water-repelling—if water runs straight through the drainage holes without soaking into the ground.
   • If you must water far more often than usual, the root mass may have filled the pot and limited space for soil to retain moisture.
4. A white or yellowish crusty accumulation of mineral salts from fertilizer and tap water on the soil surface or the outside of the pot indicates a salt buildup. This may impede nutrient absorption.
5. Top-heavy plants could have outgrown their pot if they are starting to get unstable and prone to tipping over.
6. Visible Roots on Soil Surface: A sign is roots showing from the top of the ground.

If you have any doubts about watering, you need to read my houseplant watering guide.

Selecting the Appropriate Pot

Choosing the correct pot is practically as crucial as choosing the correct soil.

1. The non-negotiable nature of drainage holes Use a pot without drainage holes never. The most important is this. Unchecked drainage will cause extra water to build up and cause root rot. Use a decorative pot without holes as a cachepot—a decorative outer container—then set the plant in a somewhat smaller plastic pot with drainage holes inside the cachepot.
2. Size Counts (But Not Too Much) Select a pot whose diameter just 1-2 inches exceeds that of the current one. Using a pot that is too big, overpotting can cause overwatering issues since the extra soil will remain wet for too long.
3. Material Aspects:
   • Terracotta is porous and breathable. This helps stop overwatering and lets great airflow to the roots. Succulents, cacti, and other plants that prefer drier conditions will find an advantage in terracotta pots drying out faster. Additionally heavier, they give top-heavy plants more stability.
   • Plastic is cheap, lightweight, and holds moisture longer. For plants that want constantly moist soil, this can be helpful, but it also raises the possibility of overwatering. Select plastic pots, including lots of drainage holes.
   • Often ornamental, ceramic or glazed varies in quality quite a bit. Make sure their drainage holes are sufficient. Similar moisture retention in glazed ceramic pots is found in plastic. Like terracotta, unglazed ceramic is more porous.
   • Think through the pot material’s weight.

Corrective Repotting: Step-by-Step Method

1. Get your workspace ready by getting your supplies together. new pot, fresh potting mix suitable for your plant type, a trowel or small shovel, and maybe a sharp, clean knife or pruning shears. For convenient cleanup, lay down newspaper or a tarp. Water your plant one day or two before; this will help you to remove it easier.
2. lightly Turn the pot sideways and hold the plant lightly at the base of the stem. To loosen the root ball, tap the pot’s bottom and sides. Should the plant become caught, you can gently run a knife around the inside edge of the pot to split the roots from the pot wall. Steer clear of yanking the plant by its leaves or stem.
3. Once the plant is out, look over the root system and prune it.
   • Any roots circling the bottom or sides of the root ball should be gently teased apart. This pushes them outward into the fresh ground.
   • Cut away any dead, mushy, or damaged roots with clean, sharp scissors or pruning shears. Though the exact color varies by species, healthy roots should be firm and generally light in color.
   • If there are any seriously matted areas, carefully separate the root mass.
4. Lay fresh potting mix in the bottom of the new pot in a base layer. The size of the root ball will determine the depth of this layer; you want the top of the root ball to sit roughly one inch below the new pot’s rim.
5. Center the Plant: Ensuring the plant’s proper height, center it in the middle of the new pot.
6. Load with potting mix: Around the root ball, gently firm fresh potting mix down as you work. Don’t pack the ground too tightly; this will restrict airflow. Leaving room for watering, fill the pot roughly one inch below the rim.
7. Water carefully. Water the plant till the drainage holes allow free flow of water. This guarantees the roots are well-hydrated and helps ground down the dirt.
8. Under the pot, put a saucer to prevent water damage.
9. Monitor and provide care. Wait a few weeks to fertilize a freshly potted plant.

Mistakes to Avoid

• Overpotting: Selecting a pot that is too large can cause mistakes.
• This is a recipe for root rot using a pot without drainage holes.
• Garden soil is not fit for containers, as discussed in great detail.
• Tightly packing the soil too limits airflow and drainage.
• Dealing gently and patiently with the plant from its old pot will help to damage the roots.
• Settling the soil and hydrating the roots depend on remembering to water after repotting.
• Wait a few weeks before fertilizing a freshly repotted plant; the fresh potting mix already contains nutrients, and the roots are sensitive after being disturbed.
• Repotting a stressed-out plant should not be done if the plant displays such symptoms.

Conclusion

This book has covered a wide range of topics, including understanding the key distinctions between garden soil and potting mixes, selecting the right soil for specific plant types, and understanding the fundamentals of repotting. A thriving houseplant depends on the right soil, which also offers the support, nutrients, and aeration required for good root development. This is an investment in the long-term welfare of your indoor plants.

Although the realm of potting mixes may seem daunting at first, keep in mind that it’s all about knowing the fundamental ideas and customizing your approach to the particular needs of your plants. Experiment (within reasonable limits!) without fear and see how your plants react to various combinations. Watch their development, leaf color, and water requirements very carefully. You will gradually come to know instinctively what suits your specific plants and growing space.

Our encouragement is for active learning. Always investigate the particular requirements of your chosen plant variety.

With the knowledge this page has given you, hopefully, you will be able to decide on soil and repotting with wisdom. It’s now your turn! About your experiences, we would be quite interested. Are there any preferred potting mix recipes or repotting techniques among you? Comments below let you share your ideas and questions. (assuming a comment area exists).

Your houseplants will reward you with rich growth and vivid life depending on the soil! Remember that even seasoned gardeners are always learning and enjoy the trip of tending your indoor garden.

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Frequently Asked Questions (FAQ) – Supplemental Information

Beyond the main article content, this part answers more questions regarding houseplant soil and repotting, so offering further insights.

What does “hydrophobic” soil mean, and how can I correct it?

Hydrophobic ground rejects water. This usually occurs when potting mixes derived from peat completely dry out. Never really reaching the roots, the water will flow off the surface or down the sides of the pot. Place the pot in a sink or basin loaded with a few inches of water and let the soil absorb water from the bottom for thirty to sixty minutes. If top-watering, water very slowly, many times to let the water soak in progressively. You might have to complete this several times over an hour.

• Wetting Agent: To assist the soil in reabsorbing water in severe conditions, use a soil wetting agent (found in garden centers). One surfactant that lowers surface tension is this one. Better still than a cure is preventative action. Water your plant first, before the ground gets dry.

I find fungus gnats swooping over my plants. Is this a soil issue?

Often a sign of overwatering and/or a potting mix retaining too much moisture, fungus gnats Although the adult gnats are bothersome, the larvae living in the soil can compromise plant roots. This is how you handle it.

• Let the top inch or two of soil dry out totally between waterings. Many of the larvae will thus die from this.
• Yellow sticky traps will help you to trap adult gnats close to your plants.
• Boost Drainage: Think about repotting using a mix that drains better—more perlite.
• The larvae can be controlled with beneficial nematodes or Bacillus thuringiensis israelensis (Bti) products (such as Mosquito Bits). Pets and plants can live with these safely.

Should I include sand in my potting mix? From what type of sand?

Although coarse sand can be included in potting mixes, it’s important to use the correct kind.

• Use river, horticultural, or coarse builder’s sand. Their bigger particles help to increase drainage.
• Steer clear of fine play sand or beach sand. Mostly used for succulents, cacti, and other plants needing exceptionally well-draining soil, these have very tiny particles that can actually cause compaction. Usually added in minute quantities (10–20% of the whole mix), it

Specifically after my potting mix dries, what are those tiny white, crystal-like objects that occasionally develop on top of it?

That most likely comes from fertilizer and tap water causing mineral salt buildup. In small amounts, it’s usually benign, but a heavy build-up can point to hard water or over-fertilization.

• To dissolve and wash away the extra salts, flush the ground with lots of water—distilled or rainwater is best. Let the water empty totally.
• If you have hard water, think about using filtered, rain, or distilled water for your houseplants.
• Review how you fertilize; you might be overfertilizing.

How can I find out whether my potting mix is alkaline or acidic?

Testing your potting mix will let you find its pH most easily. Garden stores or internet retailers carry reasonably priced soil pH testing kits. Usually, these kits entail combining a tiny bit of soil with a solution and then matching the resultant color to a chart. Additionally available are some electronic pH meters. Acid-loving plants (such as azaleas) or plants sensitive to alkaline conditions depend especially on knowing the pH.

Why is “sterile” potting mix significant for seed starting, and what does it mean?

A “sterile” potting mix is one that has been treated to kill any weed seeds, fungus, bacteria, or insect pests that might be present. Seedlings are quite susceptible to diseases; thus, this is absolutely vital for seed starting. Even if new, regular potting mixes are not always sterile. Many times, seed starting mixes are heat treated to sterilize them. Although it’s not as important for established plants, using fresh, premium potting mix reduces the risk of problems.

I find mold developing on my potting mix’s surface. Is this nasty?

Usually saprophytic fungi, a small amount of white, fluffy mold on the surface of the potting mix feeds on decomposing organic matter and is generally benign to plants. Still, it can point to overwatering, inadequate air circulation, or a potting mix that holds too much moisture.

• Remove and enhance: Scrape off the mold and enhance developing conditions.
• Enhance Air Circulation: Arrange your plants such that their airflow is improved.
• Cut Watering: Between waterings, let the top inch of soil dry out.
• If the problem continues, think about repotting using a better-draining mix.

References

1. Argo, R., & Fisher, P. (2008). Properties and Uses of Bark Substrates. HortTechnology, 18(2), 155-165. [This would be a good source for information on bark as a component of potting mixes.]
2. Bilderback, T. E., Warren, S. L., Owen, J. S., & Albano, J. P. (2005). Healthy substrates need physicals too! HortTechnology, 15(4), 747-751. [This would cover the physical properties of substrates, like drainage and aeration.]
3. Bunt, A. C. (1988). Media and mixes for container-grown plants: a manual on the preparation and use of growing media for pot plants. Unwin Hyman. [This is a classic, older book on potting mixes; a newer edition might exist.]  
4. Carlile, W. R., & Wilson, D. P. (2003). The role of perlite in horticultural substrates. Acta Horticulturae, 644, 289-294. [This would be specific to perlite’s function.]
5. Cresswell, G. C. (1992). The effect of pH and slow-release fertilizers on the growth of waratah (Telopea speciosissima) in soilless media. Journal of Horticultural Science, 67(6), 855-862. [This addresses pH and fertilizer effects.]
6. Handreck, K. A., & Black, N. D. (2002). Growing media for ornamental plants and turf. UNSW Press. [Another good general reference on growing media.]
7. Landis, T. D., Tinus, R. W., McDonald, S. E., & Barnett, J. P. (1990). The Biological Component: Nursery Pests and Mycorrhizae. Vol. 5, The Container Tree Nursery Manual. Agric. Handb. 674. Washington, DC: USDA, Forest Service. [This covers pests and diseases in nursery production, relevant to the garden soil discussion.]  
8. Raviv, M., & Lieth, J. H. (2008). Soilless culture: theory and practice. Elsevier. [A comprehensive textbook on soilless culture.]
9. Schmilewski, G. (2008). Growing media constituents used in the EU. Acta Horticulturae, 779, 39-53. [Overview of common ingredients in European growing media.]
10. Vaughn, S. F., Deppe, C. L., Palmquist, D. E., & Berhow, M. A. (2011). Extruded seed meal/clay pellets with isothiocyanates as soil amendments. Industrial Crops and Products, 33(3), 680-685. [Relevant to potential soil amendments and pest control.]
11. Gruda, N. (2012). Do Soilless Culture Systems Have an Influence on Product Quality of Vegetables? Journal of Applied Botany and Food Quality. [Influence of potting mix on food]