Houseplant Soil FAQ: Everything You Need to Know for Happier Plants

Houseplant Soil FAQ: Everything You Need to Know for Happier Plants

Choosing the right soil is one of the most important steps to keep your houseplants happy and thriving. Healthy soil isn’t just a place to anchor roots — it provides water, nutrients, airflow, and a home for beneficial microbes.

But with so many options and conflicting advice online, it can feel overwhelming to know what's best for each plant. That’s why we put together this ultimate FAQ: to answer every question you might have (and even some you didn’t think of) about soil for houseplants.

Let’s help you grow strong, healthy, and — most importantly — happy plants! 

Back to blog

General Questions

What is the best soil for houseplants?

The best soil is airy, well-draining, and matches your plant’s natural environment. Tropical houseplants like a chunky mix with bark and perlite, while succulents need gritty, fast-draining blends.

To be sure to get the right soil mix for your specific plants check out our SYBASoil guide. And if you have a plant or variety that is not yet in our guide, please let us know, as we regularly update this guide!

What is potting soil made of?

Typically a mix of peat or coco coir (for moisture), perlite or pumice (for drainage), compost (for nutrients) and bark (for structure). It greatly depends on the brand. And for plants like orchids no peat or coco coir is needed, as potting mixes for orchids are mainly orchid bark.

Can I use garden soil for houseplants?

We don’t recommend it. It’s too dense, can compact easily, and is therefore not suited to use in pots. So although it can be a great solution for your garden, it is not the best for your potted houseplants indoors.

What is the difference between potting soil and garden soil?

Potting soil is lighter, often sterilized, and made for plants grown in pots. It is often a mixture of soil improvers, such as coco coir, compost, perlite and bark. While garden soil is more compact and meant for outdoor use. Often consisting of peat, compost and composted bark.

How do I choose the right soil for my plant?

Match it to the plant’s needs: Aroids love airy, chunky mixes; succulents need sandy, gritty mixes; ferns prefer moisture-retentive but airy mixes. Check out our plant finder, for our plant specific soil advice.

Why is my plant's soil turning white?

This is usually mineral or salt buildup from water or fertilizer. Remove the top layer or flush with clean (distilled) water.

Why does my soil smell bad?

Likely from overwatering and / or anaerobic conditions, which can cause root rot. This process is not otherwise harmful, but the smell is very unpleasant. Most brands poke a hole in the bag to prevent this from happening. Leave the soil outside to air out for 1 or 2 days. The smell will then disappear.

How often should I change the soil in my houseplants?

We recommend changing the soil/repotting once any of these things happen:

  • You see roots growing out of the bottom of the pot
  • The soil dries very quickly between watering
  • The plant is top-heavy and wants to fall over
  • Roots are pushing the plant up and out of the container
  • Every 1 to 2 years, as the soil decomposes
  • The soil is very hard and compacted

Want to know more about repotting your plants? Check out our repotting blog!

How do I know if my soil is well-draining?

Water should run through quickly without pooling on top, and pots should have drainage holes. This will ensure the soil will not stay wet for too long or hold on to too much water, thereby preventing root rot.

Why is my soil staying wet for so long?

Soil may be too dense, pots lack drainage, or the plant is in low light or is exposed to cooler temperatures. Peat-based soil can sometimes stay wet for a long time, which usually isn’t a good sign as it can cause root rot and lead to compacted soil soil.

However, coco coir based soils can ALSO stay wet for a long time, but usually the structure is more airy, which makes this less of a problem. Root rot only happens when there is no air at the soil, as long as there is enough airflow there should be no issues.

How can I make my own potting mix at home?

A very basic recipe is to combine coco coir, perlite or pumice, and bark. Adjust ratios for your plant. Want to go more in depth? Each of our soil mixes has the recipe listed right on the product page. 

Can I reuse old potting soil?

Yes, but refresh it: remove dead roots, add perlite or bark, and mix in new worm castings. It also greatly depends on the type of soil you use, peat-based soils are usually harder to re-use, where high quality coco coir based soils can be re-used for a lot longer.

How do I sterilize potting soil?

In general we do not recommend sterilizing your potting soil, since most of our soil mixes contain worm castings, these provide many beneficial microfauna we like in our soils! When the soil is sterilized these beneficial microfauna would die.

These microfauna ensure healthy and happy plants. If you still prefer to sterilize the soil because of plant pests, place the soil spread out in the oven at 80–90 °C for 30 minutes or microwave small batches for a few minutes.

What does "airy soil" mean?

Soil that lets air reach the roots, helping prevent compaction and root rot. Soils that contain coconut coir, perlite, bark or pumice are generally more airy, ensuring healthy root growth.

How do I make soil more airy?

Add perlite, pumice, bark, or coarse coco chips. If you prefer you can add any of these to improve the drainage and airiness of the mix, but this is not necessary as the SYBASoil mixes are ready to use as is!

Can I mix perlite or pumice into my soil?

Yes! Both improve drainage and aeration. But all our SYBASoil mixes are ready to use as is, so this is not an absolute necessity.

What is the best soil pH for houseplants?

For most houseplants a pH around 5.5–7.0, slightly acidic to neutral would be optimal. Some plants prefer a bit more acidic soil, around 5.5 - 6.5, this includes Orchids, Carnivorous plants, Syngoniums, Alocasias and Calatheas. While others prefer a more neutral soil pH around 6.0-7.0, such as Hoyas, Ficus, Cacti, Bonsai and Terraria plants.

How do I improve poor soil?

You can try many things, it depends on what you want to improve. As a general rule of thumb you can add worm castings for nutrients and perlite or bark for structure.

How do I store unused potting soil?

In a closed container or bag, in a cool, dry place. Keep out of direct sunlight! Our SYBASoils are shipped slightly wet so if you plan to store these for some time, we recommend you dry them first! Space the mix out. Then, leave them to air dry for 2-7 days, depending on your room's temperature and humidity.

Does potting soil expire?

Not technically, but it can degrade over time. Check smell and structure before use. Also, depending on the nutrients they can become less effective over time. Normally speaking soil should last 1-2 years in storage, before becoming noticeably less effective.

What are the signs of bad soil?

Musty smell, compaction, mold, pests, or stunted plant growth.

Specific Plant Needs

What soil is best for Succulents and Cacti?

A very gritty, fast-draining mix with sand, pumice, and minimal organic matter (coco coir or compost).

What is the best soil for Orchids?

Chunky orchid bark mixes with moss and a bit of coconut husk bark, such as our orchid soil mix. For some species of orchids mixes containing less sphagnum moss and added perlite are recommended, but preferences vary widely among orchid growers.

What type of soil do Aroids need?

A chunky, airy mix with bark, perlite, and coconut coir for moisture balance, such as our Aroid mix for Monstera & Philodendron. Want to learn how to make our popular Aroid mix yourself? Check out this blog!

Do Calatheas need special soil?

They prefer moisture-retentive but airy mixes, with coco coir, perlite (for drainage) and vermiculite (for water retention) such as our calathea & maranta soil mix.

Can I use the same soil for all my houseplants?

You can, but this is not ideal. Different plants have different needs; tailor your mix when possible.

What is chunky soil mix?

Soils containing large particles like bark, perlite, or pumice to improve air flow and drainage, for example our anthurium soil mix.

What is the best soil for Fiddle leaf figs?

An airy, well-draining mix with bark, coco coir, and perlite, such as our ficus mix.

What soil is best for Monstera?

A chunky, airy aroid mix with bark, perlite, and coco coir, such as our aroid mix.

What soil should I use for carnivorous plants?

A mix of coir/peat, sphagnum moss and sand; no added nutrients, such as our carnivorous mix.

Is Cactus soil good for other plants?

Generally no. It’s too fast-draining and lacks organic matter most other houseplants need. To be sure to get the right soil mix for your specific plants check out our SYBASoil guide.

Can I use orchid bark in regular soil mixes?

Yes! It improves aeration and structure. This is a great addition for soil mixes for Hoyas, Anthuriums, Aroids or Alocasias.

Moisture, Drainage & Watering

Why does my soil develop mold?

Too much moisture, poor air flow, or organic material that breaks down. Let it dry and improve aeration. There is also a good case of mould possible, due to organic fertiliser. Don’t worry it’s totally safe for you and your plant!

It’s just nature doing its thing as organic materials break down, improving the soil and boosting plant health. Think of it as a sign your fertiliser is alive and working hard! After 2 weeks the fuzz will disappear again. Find our tips to get rid of mold here.

How can I prevent fungus gnats in soil?

Let the top layer dry, add a pumice, sand or LECA on top of the soil, and avoid overwatering. Make sure there is no water left standing in the (decorative) pot or saucer.

Why is my soil compacting?

This is generally due to breakdown of organic materials and frequent watering. Adding more chunky elements, such as bark, pumice or perlite, to a fresh soil mix will help prolong the airyness of soils.

Should I add sand to my soil?

We recommend it only for Succulents, Ficus, Ferns or Cacti’s. For other houseplants, perlite or pumice is better. Any plants with small roots will benefit from it, and it’s a fine alternative if you have no perlite or pumice on hand. It’s also great for plants who are top-heavy, as it will make the soil heavier, so the plant is more stable in its pot!

How much perlite should I add to my soil?

About 20–30% depending on how airy you want it and which plant the soil mix is made for. To give you a bit of a guideline, each of our soil mixes has the recipe listed right on the product page.

Can I add charcoal to my soil?

Yes, horticultural charcoal helps with drainage and odor control. Make sure the charcoal, biochar or activated carbon is suitable for plants before you mix it in!

What is the purpose of LECA or clay balls in soil?

They improve drainage and create air pockets around roots. We do NOT recommend putting LECA on the bottom of your plant pot to act as 'drainage holes’, it’s not a substitute for drainage holes as the reservoir it creates is not visible, so you have no clue how much water is actually in there. Which can lead to overwatering.

How can I tell if my soil is too dense?

Water sits on top of the soil and it doesn’t drain properly, roots suffocate and slowly die off, or plant growth is slow.

How to increase drainage in soil?

Add perlite, pumice or bark, this improves the airyness of the mix and thereby the drainage.

Why does my soil dry out so quickly?

This can be due to high temperatures, strong light(s), small pots, or overly airy mixes. Another issue can be that the soil contains peat, which compacts and is then unable to take up and retain moisture for a longer period of time.

Fertilising & Nutrition

Does potting soil contain nutrients?

Yes, but amounts vary depending on the brand. Many mixes contain fertilizer, which release nutrients that are taken up over time by your plants.

How long do nutrients last in potting soil?

Roughly 1–3 months, depending on plant growth, watering and the brand of potting soil. SYBASoil mixes contain fertilisers for the first 6 months after repotting.

Should I fertilize when I repot?

Wait a few weeks after repotting to avoid nutrient overload. Our SYBASoil mixes already contain enough fertiliser for the first 6 months after repotting, so we do not recommend adding any extra, as this can cause root burn.

Can I add worm castings to my soil?

Yes! It adds gentle, slow release organic nutrients and beneficial microbes. Our SYBASoil mixes already contain enough fertiliser for the first 6 months after repotting, so we do not recommend adding any worm castings during that period.

How do I know if my soil is nutrient deficient?

Your plants show yellowing leaves, poor growth, pale color, or weak stems.

Can I add compost to my houseplant soil?

Yes, but in moderation (around 10–20%) to avoid nutrient overload and potential pests. Worm castings is a better alternative.

What are organic soil amendments?

Things like coco coir, worm castings, kelp meal, or biochar to improve fertility and structure.

Can I add coffee grounds to my soil?

Better to compost them first. Raw/used coffee grounds can mold and may alter the pH of your soil.

Repotting & Maintenance

When should I repot my plant and change the soil?

We recommend repotting once any of these things happen:

  • You see roots growing out of the bottom of the pot
  • The soil dries very quickly between watering
  • The plant is top-heavy and wants to fall over
  • Roots are pushing the plant up and out of the container
  • Every 1 to 2 years, as the soil decomposes
  • The soil is very hard and compacted

What is root rot and how is it related to soil?

Root rot is caused by overwatering and poor drainage, leading to mushy, black roots. This can lead to yellowing leaves and stunted growth. And when left untreated for too long can kill your plant entirely.

How do I get rid of pests living in my soil?

Let soil dry, use sticky traps, treat with beneficial nematodes, and/or repot with fresh soil. The treatment depends on the type of pest you are dealing with.

Should I water before or after repotting?

Lightly water before to reduce transplant shock and ease root removal from the old pot. This reduces a bit of repotting stress some plants experience. Water when adding new soil after you are done repotting, so it settles nicely around the roots.

How do I remove old soil from roots safely?

Gently loosen by hand or rinse lightly with water. As a rule of thumb, most plants are okay if you damage the roots lightly, up to 20% of the root ball can be lost and the plant will still thrive.

Can I mix different soils together?

Yes, as long as the final mix meets your plant’s needs.

How do I refresh old potting soil?

Remove old roots, add new airy materials and fresh coco coir or worm castings.

Can I add slow-release fertilizer to my soil?

Yes, it provides steady nutrients over time. While most of these slow release fertilisers are designed for mineral mixes, they are also suitable for soil mixes. However most mineral slow release fertilisers do not add any beneficial microfauna, which BIO fertilisers or wormcastings do, and thereby improve soil health.

How to avoid soil mess when repotting indoors?

Use a tarp, plastic bag or large tray.

Storage & Other

How should I store soil over winter?

Dry, sealed, and cool storage to prevent pests and mold. Keep out of direct sunlight! Our SYBASoils are shipped slightly wet so if you plan to store these for some time, we recommend you dry them first! Space the mix out. Then, leave them to air dry for 2-7 days, depending on your room's temperature and humidity.

Can soil attract bugs indoors?

Yes, especially fungus gnats if the soil is kept too moist.

Can I use outdoor soil indoors?

No. It can introduce pests and is usually too dense and is therefore not suited to use in pots.

What is bioactive soil?

Soil containing beneficial microbes and/or insects to create a mini-ecosystem.

What is the difference between potting soil and potting mix?

Terms are often used interchangeably, but “mix” usually means it is a mixture of soilless components. This can be coconut coir, perlite, bark, pumice and/or charcoal.

Why is my soil hard on top?

This can be compaction of the soil, due to frequent watering and mineral buildup. Replace the compacted soil with a fresh soil mix, containing chunky materials, such as perlite, pumice or bark to help prolong the airyness of soils.

How do I loosen compacted soil?

Add airy amendments, such as perlite, pumice or bark and gently break it apart when repotting. Additionally you can add extra coco coir or worm castings to freshen up the soil.

Can I use peat-free soil?

Yes! Coco coir is a great peat alternative and a more sustainable option.

What are sustainable soil options?

Peat-free mixes, compost-based mixes, and locally sourced materials. Coconut coir is a good alternative to peat, although the shipping distance can be a bit much from Sri Lanka, where it is usually harvested, to Europe.

Why is soil acidity important?

Soil pH affects the nutrient uptake by your plant. Wrong soil pH can lead to nutrient deficiencies. This can cause stunted growth or cause spots on the leaves.

Do I need to flush my soil?

Occasionally flushing helps remove salt and mineral buildup, if you have hard water this might help. For fresh soils this is usually not necessary.

Advanced Questions

What is mycorrhiza and is it in my soil?

These are beneficial bacteria and fungi that help roots absorb nutrients. Worm castings is a great source of mycorrhiza, which will improve plant and soil health.

Do houseplants need active microbes in soil?

They help! Active microbes improve nutrient cycling and root health. While most plants can also thrive without them, in sterilised or soilless mixes, such as mineral mixes in semi-hydro set-ups.

What is the CEC (cation exchange capacity) of soil?

A measure of how well soil holds and can exchange nutrients. Higher CEC means soil can retain more nutrients. Want to know more about CEC? Read this.

Why do some soils have bark chunks?

For aeration and to mimic natural soil compositions. It’s especially great for Orchid’s, Hoyas, Anthuriums and Alocasias.

What is the difference between peat moss and sphagnum moss in soil?

Peat moss is decomposed sphagnum from bogs; sphagnum moss is harvested live and holds more water. Want to know more? Read the difference between peat and sphagnum!

What are soil conditioners?

Materials added to improve structure, aeration, or nutrient content. This can be coco coir, compost, perlite, bark or biochar. Want to know more about soil conditioners? Read about soil conditioners.

Why do some soils have a strong smell?

Decomposing organic matter, anaerobic conditions or overwatering which can cause root rot. This process is not otherwise harmful, but the smell is very unpleasant. Most brands poke a hole in the bag to prevent this from happening. Leave the soil outside to air out for 1 or 2 days.

The smell will then disappear. If the smell is more earthy, this is a sign your soil is fresh and maybe contains worm castings or other compost. Fresh worm castings are sometimes described as having a hazelnut like scent.

How does soil texture affect watering?

Yes, coarse soil drains faster; fine soil retains more water. Different plants have different preferences in soil texture and drainage.

Can I grow hydroponically without soil?

Yes! You can use water and mineral mixes. This is often called (semi) hydro(ponics).

How do professional growers make their soil?

They tailor custom blends for drainage, aeration, and nutrients using high-quality components. To give you a bit of a guideline of what those blends could look like, each of our peat-free soil mixes has the recipe listed right on the product page.

DIY & Troubleshooting

Can I make a soil mix for propagation?

Yes, make a very airy, nutrient poor mix. Often for propagation only perlite, coconut coir or moss is used until roots have developed and the cutting is ready to be repotted. Want to learn more about how to make propagations of your plants? Read more on propagation!

How do I prevent root-bound issues in soil?

Repot regularly and choose slightly larger (2-3cm bigger in diameter) pots when needed.

Can I add gravel to improve soil drainage?

Best to mix drainage materials throughout rather than layering at the bottom. We do NOT recommend putting Gravel on the bottom of your plant pot to act as 'drainage holes’, it’s not a substitute for drainage holes as the reservoir it creates is not visible, so you have no clue how much water is actually in there. Which can lead to overwatering.

Why does my plant keep tipping over in its soil?

This can be due to various reasons, either the current pot is too small, as the plant has grown the pot is no longer able to support the plants weight. The soil mix is too loose, which does not support the roots enough. Or roots are shallowly placed within the pot.

How do I make a cheap soil mix?

Combine coco coir, perlite, and worm castings— skip more expensive additives, such as pumice, lava gravel or active carbon.

How to get rid of algae on the soil surface?

Improve air flow, reduce watering, scrape off the top layer and treat with diluted hydrogen peroxide.

What is the difference between vermiculite and perlite in soil?

Vermiculite retains more water, while perlite improves drainage and aeration. This makes vermiculite a great soil mix addition for alocasias and carnivorous plants.

Perlite is great for Aroids, Bonsais, Ferns and Universal soil mixes. What to learn more about the differences between vermiculite and perlite? Read about the difference between perlite and vermiculite!

Can I grow plants in 100% compost?

We would not recommend it, as compost or worm castings are too dense (both in texture and nutrients) and moisture-retentive. This can lead to root rot and nutrient burn.

Is coco coir better than peat in soil mixes?

Yes, it’s generally seen as better as it is more sustainable and similar in function. Coco coir compacts less and is less likely to waterclog, both can lead to root rot. However peat is more acidic, which leads to better nutrient uptake by some houseplants.

Due to coco coir lasting longer, providing more aeration to the soil and being a more sustainable option we consider it better than peat!

Can I use aquarium soil for houseplants?

No, it may hold too much water and isn’t designed for pots. Some aquarium soils such as fluval stratum are great for propagation and rooting alocasia corms.

Mix customization

How do I make a chunky mix for aroids?

Use bark, perlite, coco coir, and a bit of worm castings. Add organic nutrients as well for quicker growth! For aroids that are sensitive to root rot, we would generally recommend our anthurium soil mix.

What is a semi-hydro soil mix?

A mix with LECA or other inert media like zeolite, pumice or lava rock. The mixes consist of completely mineral components and are used in combination with selfwatering pots, to create semi-hydro(ponics) setups.

Should I rinse soil additives before mixing?

Yes, for most soil additives this is recommended to remove dust and impurities.

What ratios should I use for different plants?

We have a recommendation per plant type on our coco mixes product pages! So you are able to mix our expert soil mixes easily at home.

What are the best ingredients for a DIY soil mix?

Coco coir, perlite, bark, and optional activated carbon or worm castings. To be sure to get the right DIY soil mix for your specific plants check out our plant finder.

Can I mix soil from different brands?

Yes, as long as it fits your plant’s needs.

How to make soil lighter without losing nutrients?

Add perlite instead of sand or pumice. This will increase the aeration of the mix. We would not recommend doing so for Lithops, Split rock plants, Carnivorous plants or terrarium soils.

How to make soil pest-resistant?

Use sterile components, good aeration, and beneficial microbes if needed. This will help prevent pests, but it will never mean your soil is fully pest resistant.

How to balance water retention vs drainage?

Adjust ratios of coco (retains water) and perlite/pumice (drains water) according to your plant’s needs. We have a recommendation per plant type on our houseplant soil product pages!

Can I add bark chips to all my soil mixes?

Yes, if the plant prefers an airy mix. So, this would not be beneficial for Calatheas, Marantas, Carnivorous plants, Lithops, Cacti and Succulents.

Extra Questions

Why is there green moss growing on my soil?

High moisture, compact soil and low airflow. It’s mostly harmless but can indicate overwatering. The moss can be scraped off, but drainage and airflow will need to be improved to prevent the moss from growing back.

What to do if my soil smells like ammonia?

Likely anaerobic decomposition, which can cause root rot. This process is not otherwise harmful, but the smell is very unpleasant. Most brands poke a hole in the bag to prevent this from happening.

Leave the soil outside to air out for 1 or 2 days. The smell will then disappear. Always inspect your plants roots if this is the case, to monitor for root rot.

How to make soil fungal-resistant?

Good aeration, sterile ingredients, and beneficial microbes. This will help, but not fully make your soil resistant to fungal infestations.

Can I use forest soil for houseplants?

No, it may contain pests and is too dense, and is therefore not suited to use in pots. So, it is not the best for your potted houseplants indoors.

Can I microwave soil to sterilize it?

Yes, for small batches (1–2 minutes), but do so carefully to avoid overheating. In general we do not recommend microwaving your potting soil, since most of our soil mixes contain worm castings, these provide many beneficial microfauna we like in our soils!

When the soil is microwaved these beneficial microfauna would die. These microfauna ensure healthy and happy plants.