Indoor plants rely almost entirely on compost for nutrition. This is because your potting soil may lose plenty of beneficial nutrients as the plants grow. To give your plants enough nutrients, you must reintroduce the depleted organic material at some point during the process.
The goal is to find a compost with sufficient nutrients to support the plant’s growth and health.
The best compost for indoor plants should be well-drained, nutrient-rich, and free of harmful chemicals or pathogens.
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Why Do Indoor Plants Need Compost?
While proper lighting and watering are essential for indoor plants, compost also plays a significant role in healthy growth.
Compost is a natural mulch that helps your soil balance nitrogen, potassium, and phosphorus levels, and it also keeps soil from drying out and protects your plant from over- or under-watering.
You can use indoor plants composted in the primary soil or mixed into an existing potting mix. Check the ingredients list on commercial compost before use. This ensures that your indoor plants enjoy the necessary nutrients from compost.
If using homemade compost, keep in mind the following:
- A well-done compost appears crumbly and dark and produces an earthy scent.
- The breakdown process reduces the volume of compost ingredients by almost 50%.
- Overall, the presence of green waste or food scraps indicates a poorly done compost not properly aged for your garden soil.
The Best Composts to Use for Indoor Plants
Finding the best compost, whether for repotting or a new application provides enormous benefits to indoor and outdoor plants.
For your indoor plants, experts recommend three types of compost.
1. Loam-based Compost
In a nutshell, loam compost improves aeration and drainage in the soil. Unfortunately, finding the best quality of loam is complex because it is currently in limited supply. This makes it difficult for homeowners to obtain beneficial loam compost for their plants.
Loam-based compost contains peat, grit/sand, loam, and plant matter. It also has an equal amount of clay and silt.
Although sand particles are the largest, they only hold a small amount of water. Clay, on the other hand, easily absorbs moisture due to its small size.
Finally, there is silt, which contains clay and sand particles. The beauty is that mud allows better mixing on your compost pile.
2. Multipurpose Compost (Peat-free)
Amazon stocks some of the most nutritious multipurpose compost. The structure of these products is also ideal for certain plants, such as orchids. Still, the high organic matter content may occasionally sink to the bottom during the breakdown process.
Apart from poor aeration, this also impacts your indoor garden’s moisture buildup and plant root growth.
However, you can reverse the situation by:
- Add drainage materials such as horticultural sand in a ratio of 4:1 (compost to sand).
- Succulents and cacti are two other preferred options. Add them in a balance of 2:1.
- Vermiculite adds value to your DIY project by increasing air porosity. Apply it in a 2:2 balance because it can hold water and slowly release it to your house plants.
- Perlite, a type of volcanic glass, is also a great addition to multipurpose compost. Perlite does not retain water because of its permeability, but it is ideal for garden soil on patios and balconies. In a 4:1 ratio, add it to your compost when necessary.
- The final option is biochar, which functions similarly to vermiculite. Although uncommon, use it in the exact quantities as perlite or sand.
3. Houseplant Compost/Potting Mixes
Potting mixes are a good source of organic material specially designed for plants in containers and pots. They are often light in weight, drain well, and rarely retain excess water.
You can also use it for your outdoor space because it contains an ideal combination of perlite, vermiculite, sphagnum moss, and peat moss.
More importantly, it provides sufficient nutrients to your plants over time through a slow release process.
Keep in mind the following when using potting mixes:
- When purchasing potting mixes, choose a brand with adequate wetting agents to allow it to spread evenly and improve drainage.
- Moisten the compounds with warm water before planting your plant. This saves you the time and effort of mixing the content with the soil inside the pot.
- Replace potting mixes every one to two years. To prevent pest and disease attacks, add at least 50% fresh mix during this time.
How to Use Compost Indoors
The amount of compost required in an indoor garden depends on the plant and the size of your space.
You can add more compost if you have ample indoor space, such as a greenhouse with plenty of light. If space and light conditions are limited, start with a small amount.
There is also no set time for adding compost to your plants. Nonetheless, nutrients have ample time to incorporate into the soil if you do it in early spring or late fall.
A maximum period of about a fortnight before planting ensures the best plant care.
- Place your pots carefully when potting to avoid contaminating your indoor space.
- Scoop an inch of compost from the top of the soil and replace it with a fresh mix during the repotting process.
You can make your compost and adjust the number of ingredients needed based on the needs of your plants.
How to Make the Best DIY Compost for Indoor plants
Here are some secrets to making the best compost for indoor plants.
- Use small amounts of fresh grass clippings.
Vast amounts of grass clippings may be too dense and compact for composting. They are also high in water which can supply your pile with excess water.
- Avoid raw meat scraps or bones.
These items take much longer to decompose and will foul up your compost over time.
- Look for locally grown ingredients.
Avoid using compost made from non-native materials in your area—this help to prevent pests and diseases from attacking your indoor plants.
- Do not use unhealthy or sick-looking plants.
Pathogens in dead or living plants can contaminate your pile and entire compost. Still, plants recently treated with herbicides and pesticides may alter the compost bin temperature and affect the C/N ratio.
- Refrain from pet waste
Pet waste carries many unhealthy parasites transmittable to other animals and humans.
There are specific requirements that homeowners should meet to compost the trash safely and kill pathogens.