If you have indoor plants or are planning to buy some, you’re probably wondering, “Can I Use Dirt From Outside To Grow Pot Plants Indoors?” Most people will immediately say yes because soil is soil, and every plant needs soil to grow. Unfortunately, the answer isn’t that simple.
You might feel tempted to use the soil from your garden, but that could end up doing your inside potted plants more harm than good. Instead, have a read of my reasons why using outside dirt for house plants may not always be a good idea, and consider what you can do as an alternative.
Using Outdoor Garden Soil for Indoor Plants
Generally speaking, you can use outdoor soil for your plants in the garden and they will thrive. This is because the soil in your garden can retain water during dry seasons and drain off excess water when it rains. It also contains beneficial microflora and microfauna — microorganisms that help with aeration and breaking down nutrients.
In addition, rodents and insects like to burrow, find food and take residence in soil. These activities are great for our dirt because it contributes to creating aeration in the soil.
These factors combined work together to make the garden soil healthy for outdoor plants.
Potted plants, on the other hand, don’t fare too well with outdoor soil. They tend to lack vitality and overall health when they are planted in outdoor garden soil. This can be for a number of reasons including the density of the soil, a depletion in nutrients, or exposure to pests or diseases. It’s often the case that outdoor plants have stronger roots than potted plants and are therefore more robust and hardy. They are able to survive in harsher conditions and sometimes less favorable soil conditions too.
Risk of Pests & Diseases
There are many reasons not to use garden soil for potted plants, and a major reason is the risk of disease. Houseplants also tend to fall victim to pests that are present in the soil. Some common pests and diseases caused by outdoor garden soil include pot worms, aphids, and Botrytis blight.
Pot worms are similar to earthworms. They perform the same function — providing aeration in the soil. Pot worms feed on waste in the soil and, by doing so, provide aeration. Although they are beneficial, they tend to multiply quickly.
If you don’t take care of pot worms before they become too many, they will feed on all the waste in the soil. After feeding on the waste in the soil, they will feed on your plants.
There are some species of worms you can find in your outdoor soil, including pot worms, earthworms, grub worms, nematodes, and red wigglers. The most dangerous ones are the nematodes and grub worms.
- Nematodes: They are usually harmless, although different nematode species are poisonous to humans, animals, and plants. They are not usually found in potted plants unless you put an outdoor plant in the pot or use outdoor garden soil.
- Grub worms: These are beetle larvae. They are usually small, white, and fat. They tend to target your plant’s roots and will eat them up after a short while. After this, they move to leaves and stalk.
Here are some signs you will see if your plant is suffering from a worm infestation:
- Worms on the soil surface
- Holes in leaves
- Plant is wilting because its roots have holes
Here are some ways to deal with an infestation:
- Soak the plant to get rid of the worms
- Repot the plant
- Use a natural predator such as fireflies or frogs
- Use an organic or chemical agent
Aphids are usually found under a plant’s leaves. They tend to feed on the plant, then produce a secretion that remains on the leaves. The secretion prevents the leaves from receiving sunlight, which in turn prevents photosynthesis.
- Yellow leaves
- Leaves with holes
- Plant begins to wilt because of lack of sunlight
- Presence of aphids under the leaves
You can get rid of aphids by spraying your plant with water mixed with insecticidal soap until all signs of the pests and their eggs are removed.
If you have a plant with bigger leaves, you can use a plant-safe piece of cloth that has been wet with the insecticidal mixture to wipe the leaves. Continue to spray and wipe regularly until all visible signs of the infestation have gone.
You should also move the infected plant away from other plants and give these other plants a thorough check for any signs of reinfestation.
Botrytis blight, or gray mold, is a fungal infection that affects many indoor plants. The causative fungus attacks the plant when there is a high level of humidity.
The signs of Botrytis blight are:
- Discoloration of flowers
- Rotting of fruit
Here is how to treat botrytis blight:
- Good sanitation
- Picking up and burning all infected plant parts
- Using a fungicide
Soil pH and Nutrients
The pH level of your soil matters greatly when it comes to your potted plants. Where you live dictates the pH level in your outdoor garden soil, and the pH level could be harmful to your potted plants. It is much safer and better for your plant to be planted with a potted plant mix that is conducive to the requirements of your house plant.
Your outdoor garden soil also might not contain the necessary nutrients for your inside plant. This can lead to leaf drop, browning or curling of leaves, deformity, an increased risk of disease, or even the death of your plant. On the other hand, the soil could have a high concentration of nutrients or too much or too little acid or alkaline. All this could lead to soil toxicity which can be absorbed by your houseplants.
Accidentally Used Garden Soil for Potted Plants?
If you accidentally planted your indoor potted plants with outdoor garden soil, there is a chance that your plant won’t make it. If you’ve realized this early on then there is a chance it can be fixed, however.
The first step you need to take is to remove the plant from its pot or container. Once you’ve done that, pour the soil in a spare bucket, clean the pot, replace the dirt with indoor plant soil, and then carefully repot the plant.
Using Bagged Garden Compost Indoors
Compost helps plants grow. This is because of its composition — manure, lawn trimmings, and other animal and plant matter. Many people wonder if they can use compost for indoor plants because most of what it consists of is typically found outdoors.
You can use bagged compost for your indoor plants since it provides them with nutrients. The amount of compost you will add to your indoor plant will depend on its size and its pot’s size.
When adding compost, it’s important to get the balance right. Using too much can be harmful and may add too much nitrogen to the composition of your soil while too little won’t provide the plant with enough nutrients.
As a rule of thumb, the best thing to do is add an inch of compost to your plant’s soil. Try to blend and add the compost near the plant’s roots to ensure you don’t disturb or harm the soil. You could increase the ratio of compost to the soil as the plant grows, adding fresh compost at least two times a year.
Using Outdoor Potting Compost for Houseplants
When you have half a bag of outdoor potting compost leftover and you’d rather use it up than leave it on the shelf and run the risk of it expiring, it’s tempting to want to use it when repotting indoor plants. Although this doesn’t apply to every plant, potting compost can work well as a substrate for some houseplants.
Make sure you know what the composition of the potting compost is and then research the type of soil your house plant needs. Some plants thrive on nutrient-rich, acidic, and nitrogen-heavy soil and since potting compost is made up mainly of organic matter, this is perfect for them.
On the flip side, many house plants need well-draining soil and often potting compost will not contain ingredients such as perlite of bark that help with this so always consider adding additional ingredients to get the mix that your indoor plant needs.
Overall potting compost is preferable to using outdoor garden soil, as the compost is less dense than the garden soil.
One further matter to consider is the odor that organic potting compost may omit. If it’s made of 100% natural ingredients it is likely to smell, well, natural! What can seem perfectly normal in an outdoor space may smell somewhat offensive to us humans especially in confined indoor space. Also, organic matter is usually highly attractive to domestic pets. The last thing you want is your dog or cat digging up your precious indoor plants.
Outdoor Vs. Indoor Potting Soil
Although outdoor garden soil and potting soil both offer benefits to plants, they are not interchangeable.
Outdoor soil is the soil you find in your garden and can contain clay, sand, stones plus other naturally occurring minerals relative to the region. The amount of water, nutrients, and microorganisms it contains along with the pH level (how much acid or alkaline it contains) will differ from one backyard to the next.
Potting soil, on the other hand, is mixed using specific ingredients with the specific growing needs of window boxes and potted plants in mind. It is typically less dense than outdoor garden soil, which makes it easier to handle when potting houseplants and for drainage purposes.
Difference Between Indoor Potting Mix and Compost
A potting soil mix can be made up of components such as pine bark, peat moss, and vermiculite or perlite. It can also contain organic matter such as bat guano, bone or blood meal, and worm castings. The market is flooded with options depending on your specific houseplant needs. Quite often indoor potting mixes are steam-heated to minimize the risk of diseases or infestations.
Compost begins life as specific items of household waste. Items such as vegetable peelings and scraps, eggshells, tea leaves, coffee grounds, bits of cardboard, grass clippings, leaves, twigs, and pine needles are left to mingle together over time to form a nutrient-rich, 100% organic soil that is full of nutrients.
Aeration and Drainage
Aeration is crucial both to soil and to plants because it enables oxygen to circulate. Without oxygen the microorganisms that provide nutrients to enrich soil would not be able to survive, plants would not be able to convert food into energy in order to grow and compost would not decompose effectively.
Ensuring sufficient aeration in soil occurs both naturally and with some intervention from man. Rocks, stones, worms, critters, and rodents all serve to move the soil so that little pockets of oxygen are made. Turning soil by regularly digging with a spade, fork, or till can also serve as highly effective in aerating soil. In potting soil and compost adding ingredients such as grit or vermiculite can help to create these all-important little pockets of air.
Drainage prevents these pockets of oxygen from getting filled up with water and helps any pools of water to flow more freely. Good drainage is vital for the health of your plants to ensure that their roots are able to absorb oxygen as well as water.
Best Potting Mix for Indoor Houseplants
The soil needed for most house plants has to be one with very good drainage. This will ensure that roots are not allowed to become soggy and waterlogged.
You’ll need a soil mixture that has good aeration but also has the ability to retain a small amount of moisture. A 50/50 mix of coco coir or peat combined with grit, orchid bark, perlite or even clay balls is a good place to start. If you find that your potting compost remains soggy try adding a little sand for even more drainage.
Using commercial houseplant soil with a bit of extra grit or pumice mixed in is a great option too. If you need a commercial soil recommendation,
I suggest trying Espoma Organics Potting Mix combined with extra perlite or grit.
Buying a good quality potting mix for your indoor plants means that you know what you are getting and you can read up on the list of ingredients and match it to the requirements of your plant.
You also get the wisdom and knowledge of other people who have used that particular product if you can read reviews before you buy.
You can, of course, make some yourself. If you have lots of houseplants or you are on a budget then this is a good option. Keep reading to find out what goes into making a healthy potting mix.
Best Indoor Potting Soil Ingredients
The following are the best ingredients for making your own indoor potting soil:
- Coco Coir: Great for moisture retention, eco-friendly and a good substitute for peat moss
- Perlite: This volcanic glass aids in the aeration of the soil
- Vermiculite: A naturally occurring hydrous phyllosilicate mineral that absorbs water and helps retain moisture
- Compost: This nutrient-rich organic soil can be used as an alternative for peat moss, but make sure it’s not too much to reduce the over-retention of moisture
Houseplant Potting Mix Ratio
Now that you know the ingredients for a potting mix, the next thing is to understand the correct ratios of the necessary materials. The ratio of each depends on the size of your container, but there is a rough estimate for the balance. Here is the recipe:
- 1 part material to aid with aeration/drainage (perlite or veermiculite)
- 1 part woody material (pine bark)
- 1 part material to help with moisture retention (coco coir or peat moss)
- 1 balanced houseplant fertilizer
Verdict: Can I Use Dirt From Outside To Grow Pot Plants
Using outdoor garden soil for your houseplants and indoor potted plants can cause more harm than good. Outdoor soil does not have the correct nutrient balance, or drainage to meet the specific requirements of houseplants and this will prevent them from thriving.
Choose instead, a good quality potting soil that can either be shop-bought or homemade and tailor it to the needs of your beloved plants. After all, they deserve it! They offer so much to your indoor space and demand only a little in return.