Best Way To Use Outdoor Soil for Indoor Plants

Introduction

Bring a little bit of Mother Nature into your house by practicing indoor gardening. It is a fascinating hobby in which various indoor plants and flowers help transform an area. Nonetheless, the right kind of soil is essential for indoor plants. Although outdoor soil might be the easy solution, some important issues arise between outdoor and indoor soil.

Outdoor soil is created to help plants grow in extreme open conditions where natural factors such as rainfall, sunlight, and wind are available to the plants. On the other hand, indoor varieties have even more specific requirements. Since they live in pots, space is limited for them, and they are subjected to indoor-controlled conditions. This distinction requires indoor soil to be specially formulated to enhance these aspects with good drainage, aeration, and moisture retention.

In this article, we will look at the advantages and disadvantages of using outdoor garden soil for your indoor plants, the dangers of using outdoor soil indoors, and ways to treat outdoor soil for indoor use.

The Need for Special Soil for Indoor Plants

Growing indoor plants entails growing them in pots, and their growing conditions are very different from those of regular plants. Unlike outdoor plants, which have an unlimited amount of soil to expand their roots and obtain moisture and nutrients from the environment, indoor plants are grown in pots. This means the root space is limited, moisture in the soil can change humidity levels, and it often limits exposure to vital microbes from outdoor soil.

Here are several key factors that make indoor plants’ soil requirements different from those of outdoor plants:

Drainage and Aeration Requirements

In nature, excess water can drain away from the roots of a plant, making it possible for oxygen to penetrate the plant’s root zone. However, pots and other containers do not always have the same drainage and are not able to efficiently drain soil, making the soil easily waterlogged.

Moisture Retention Ratio

The small amount of moisture that potting soil indoors retains should be in the correct amount, as over-saturation of water is dangerous for the growth of the plant.

Nutrient Availability

Plants that are grown outdoors can make use of nutrients from decaying organic matter, animal matter, and bacteria that are all present in the soil.

Joint Factors of Indoor Environment

Indoor plants are exposed to a constant room temperature, less solar exposure, and lower amounts of humidity.

Problems with Indoor Use of Outdoor Soil

Pests: Soil obtained from outside can contain insects such as fungus gnats, aphids, or spider mites, which are not suitable for an indoor environment and can spread to other plants.
Pathogens and Fungi: Soil harvested from the outdoors is often contaminated with bacteria, fungi, and mold spores. When exposed indoors, these can cause diseases like root rot and powdery mildew.
Nutrient Imbalance: Soil found outdoors could be deficient in nutrients required by indoor plants or rich in nutrients that can scorch the roots. Most indoor plants require a well-balanced and controlled nutrient supply that outdoor soil may not provide.
Unwanted Weed Growth: Soil from outdoors may also contain weed seeds that can germinate indoors and compete with seedlings for space and nutrients.
Variable pH Levels: Because indoor plants have specific requirements, outdoor soil is inappropriate due to its variable pH levels, which can lead to problems in nutrient absorption.

These are some of the problems posed by the use of outdoor soil for indoor planting, making it inappropriate for healthy indoor plant growth.

Prepping Outdoor Soil for Indoor Cultivation

Indoor plants can be grown easily with outdoor soil, but making some modifications is essential for indoor usage. Below is a step-by-step guide for the appropriate preparation of soil.

Soil Sterilization: Soil from outdoors can contain pests and weed seeds. These can be dealt with by sterilizing the soil. Soil can be sterilized by placing it in an oven at 180ºF (82ºC) for 30 minutes in small batches. A microwave can also be used for a 90-second cycle. This process is beneficial as it eliminates many microorganisms, but caution should be taken as it can produce an unpleasant smell.
Enhancing Drainage and Aeration: Outdoor soil is heavier, clumps more when put into pots, and has lower drainage. Proper aggregates like perlite, vermiculite, or coarse sand should be used to enhance the drainage ability of the soil. A suggested mix is about two parts outdoor soil to one part additive, such as perlite, which yields excellent drainage that keeps plants from being overwatered while also allowing roots to access oxygen.
Improving Nutrient Quality: The nutrients that would be ideal for houseplants are likely absent in soil derived from outdoors, or it may have very little organic material. Add compost or appropriate indoor plant fertilizer to ensure the indoor soil contains plenty of nutrients.
Monitor Soil pH Level: For indoor plants, such as orchids, coated anthuriums, and others, many prefer their soil pH level to be slightly acidic (a convenient range is between 6.0 and 7.0). It is best to assess the pH of the soil using a pH testing kit available for purchase. Lime can be added if the pH is too low; likewise, sulfur can be used to reduce the strength of the pH if it is too high.
Use a Potting Mix: It is advisable to create potting soil that is a combination of outdoor soil and commercial potting soil. A mixture composed of one-third outdoor soil and two-thirds potting mix helps mitigate the risks involved.

Adhering to these guidelines significantly improves the conditions beneficial to the development of your indoor plants, decreases the chances of pest infestation, and ensures proper root development.

Best Indoor Plants for Mixing with Outdoor Soil

With a little preparation, certain indoor plants can tolerate outdoor soil blends fairly well, as they are quite hardy. The following are a few indoor plants that do reasonably well with a combination of outdoor and potting soil:

Pathos: Pathos is particularly good at tolerating a variety of soil types, making it suitable for outdoor soil mixes.
Snake Plant (Sansevieria): Snake plant is low-maintenance and can handle different soil types as long as it drains well, making it suitable for an outdoor soil mix.
ZZ Plant: These plants are drought-resistant and can tolerate a range of soils as long as they are not densely packed and are well-aerated.
Spider Plant: Pretty tough to kill, spider plants might struggle in too dense or waterlogged soil, but they can adapt to a wide variety of soil types.
Jade Plant (Crassula ovata): These plants thrive in well-draining mixtures, so they will be able to grow in sand-dominated outdoor soil blends, provided there’s perlite for drainage.

These plants tend to be quite tolerant and easy to work with, but make sure there is proper drainage, and watch out for potential problems when mixing soil for outdoor use.

Common Signs of Soil-Related Problems in Indoor Plants

Soil-related concerns can manifest in several ways, showing signs of illness in your houseplants. Here are a few common signs to notice and some steps to take:

Root Rot:
- Symptoms: The soil appears mushy and has a bad odor, or leaves start to wilt or yellow.
- Cause: Compacted soil cannot drain well, regardless of watering.
- Solution: Remove the plant from its container, cut any damaged roots, discard the bad soil, and replace it with new soil that drains well. Remember to punch holes in the pot and control the amount of water you provide.
Yellowing Leaves:
- Symptoms: The older leaves, in particular, turn yellow, and plant growth becomes poor.
- Cause: This could be due to a couple of reasons: insufficient nutrients in the form of nitrogen or iron fertilizers, or too much water.
- Solution: Inspect the soil and pH, if possible. It’s necessary to regularly apply fertilizer to plants, or better yet, add compost mix to the soil.
Pests:
- Symptoms: Whole leaves or parts seem infected, and insects such as aphids, mealybugs, or fungus gnats are present in the soil.
- Cause: Soil conditions outdoors may lead to these bugs being present, which could be carried indoors.
- Solution: Examine the plants and soil for insects regularly. If any are found, apply insecticidal soap and sticky neem oil directly over the soil and the plants.

Maintaining Soil Health in Indoor Plants

Your indoor plants will greatly benefit from healthy and nutritious soil. Here are some steps to ensure that the soil is maintained as required:

Watering: Excessive watering leads to waterlogged soil, which can contribute to root rot. Water only when the top inch of soil feels dry, and ensure there are adequate drainage holes in the pot to allow excess water to flow out.
Change the Soil: Compressed indoor soil can become nutrient-deficient over time. Invest in nutrient-rich compost and apply it to the top few inches of the soil; this also helps enhance the soil’s structure.
Do Not Hesitate to Repot: Soil can become poor in nutrients, and plants may outgrow their pots. Repot your plants every couple of years, or whenever roots cramp the pot, using a new potting mix each time for durability.
Humidity Control: High amounts of dry air in indoor spaces can cause the soil to dry out more quickly than necessary. Mist the leaves and/or use a humidifier or position a water tray next to the plant to boost humidity around the plants.

Can You Use Outdoor Soil for Your Indoor Plants?

Outdoor soil for indoor plants appears to be an attractive and inexpensive option, but it is not as easy as it sounds. Outdoor soil can bring along pests or pathogens and may be poorly drained, which can harm your plants if not dealt with correctly. However, by mixing in potting soil, sterilizing the outdoor soil, adding drainage, and enriching nutrients, it is possible to use outdoor soil.

Mixing outdoor soil with a commercial potting mix can make it suitable, especially if you’re using hardy plants such as pathos, snake plants, and ZZ plants. Ultimately, it’s up to you to determine whether outdoor soil is good for your houseplants based on how much you alter the mix to accommodate your specific plants.

If you have any doubts about mixing potting soil or are experiencing issues, it is wise to choose potting soil that is readily available in the market. In essence, you can successfully make your indoor and outdoor plants grow and flourish, as long as you care for them, regardless of the soil type being used.