Houseplant Soil Explained: An Interview with Sybren Bies of Sybotanica

 

Soil is one of those parts of houseplant care that’s easy to overlook. It sits quietly under the surface, and if a plant looks healthy, we tend not to think about it much at all. But when things start going wrong, soggy compost, stressed roots, and the slow slide into decline, it’s often the substrate that’s doing the heavy lifting.

We’ve been interested in Sybotanica for a while because their approach feels unusually practical. It’s led by testing, observation, and a clear effort to make the confusing bits of plant care simpler for real homes. We sat down with founder Sybren Bies to talk about how the brand began, why substrates matter more than people think, and what he’d want every grower to understand before they change a thing.

For readers discovering Sybotanica for the first time, can you tell us a little about how the brand began and what first drew you to substrates rather than plants themselves?

Sybotanica started in my bedroom. I’d been making my own soil for quite some time for different kinds of houseplants, mainly because I found it surprisingly hard to source the right materials and properly experiment with what actually worked.

At the time, I was also selling cuttings, plants, DIY terrarium kits and even isopods. But focus is important. Over time it became clear that substrate was the part of plant care where I could make the biggest difference, so I decided to go all in on houseplant soil.

Substrates are often treated as an afterthought by houseplant growers. Why do you think they play such a central role in long term plant health?

I see substrate as something that makes everything else easier. When your soil more closely mimics the original habitat of a plant, watering becomes simpler and more predictable. The right mix also supports steady nutrition, which helps plants grow better and makes them more resilient to pests and other issues.

A good example is Calathea. They can become very dramatic as soon as the soil dries out. We add vermiculite to their mix because it holds water for longer. In practice, that means you don’t have to be quite so perfect with watering.

Many people struggle with standard composts without really knowing why. What are the most common issues you see, and how does a more considered mix help?

The biggest issue I see is the balance between water retention and oxygen around the roots. Compost based mixes tend to be quite heavy, which increases the risk of roots sitting in wet, airless soil.

Another very common problem is the lack of drainage holes. You can sometimes get away with it if you’re extremely careful, but I don’t see many reasons not to use them. Roots need both water and air, and drainage makes that balance much easier to achieve.

Your approach feels very education led rather than trend driven. Was that a conscious decision from the beginning?

I’ve always been very into the technical side of soil. We’ve also consciously invested in getting experienced biologists on our team who really understand soil biology.

We’re starting by introducing the universal blend to our customers. Who is that mix designed for, and what kind of growing situations does it suit best?

It’s perfect if you just want to get started and try out what the combination of worm castings, lava gravel and organic nutrients can do.

It’s funny because I didn’t want to launch this product at the start, but one of our biologists kept pushing for it because we were getting requests often. We decided to test it, and now it’s actually one of our best selling mixes.

The Universal Mix, or the Base Mix if you don’t want perlite, is also great if you want to start experimenting. You can begin with a bag of that and then add soil improvers you already have at home to create more custom mixes for different plant types.

Sybotanica has built a strong following across Europe. How do you think about engaging new growers, particularly those earlier in their substrate journey?

We publish a lot of content about how to use soil mixes, plus practical tips, and we try to make it as easy as possible for people to pick the right mix.

A great example is our SYBAScan tool. We built a web based app that advises the right soil mix based on an uploaded picture. We’ve also done quarterly surveys and interviews for years, and we focus on making everything we put out into the world simple and usable.

There’s a lot of noise in the houseplant world around miracle solutions and one size fits all advice. How do you decide what’s genuinely useful versus what’s just marketing?

Our best answer has always been to test it. We also fact check against studies where we can.

We’re strict about what we keep selling. We’ve removed more products than we added in the past year because we need to see a real use case for something, and we don’t want to overwhelm customers. While we’re experimenting with a new product line in the pest control space, most of our effort goes into improving existing products.

Looking back on building Sybotanica, what’s one business decision you were very confident about at the time that didn’t work out as expected?

Way too many things to put into one answer, but I lost a lot of money on isopods. I bought expensive starter colonies and underestimated the level of care they needed.

Conversely, what’s a decision that felt risky or uncomfortable at the time but ended up shaping Sybotanica for the better?

The scan tool took around a year and a half. We thought we could do it in a month or two. It was expensive and took a lot of work to fine tune, well over a thousand hours, but now it’s widely used by our customer base.

We thought about stopping the project a couple of times but ultimately kept going. We made it free to use, so we actually get a lot of non houseplant identifications too from people who just want the photo recognition functionality. It’s very popular in Spain for some reason we still haven’t figured out.

Finally, for someone curious about substrates but unsure where to start, what’s the single most important thing you’d want them to understand?

Use plant pots with drainage holes. It’s one of the most common issues we see in customer service. Even with the right soil, if roots are suffocating in water the plant will not be happy.

The second thing is to think about where the plant came from and how it lived in its original habitat. Most houseplants are conditioned to do well in homes, but it helps to understand what their natural conditions were like, and how that habitat behaves.

And don’t be afraid to test. I like taking a few cuttings from a mature plant and putting them in different substrates to learn what works best. It’s also a good way to experiment with fertiliser types, methods and frequency.

What we like about Sybren’s approach is how unromantic it is, in the best way. Better soil does not promise miracles. It simply gives roots the air and structure they need, and makes watering less of a guessing game.

If you take one thing from this, it’s probably the most boring advice in the world, and also the most useful. Start with drainage. After that, think habitat, then test gently and learn from what your plants tell you.

About Sybotanica

Sybotanica is a houseplant substrate brand focused on practical soil mixes and clear, easy to use plant care resources. Built around experimentation and observation rather than trends, their mixes combine structured aggregates, organic nutrients and purpose-designed materials to support healthier roots and more predictable watering.

Sybotanica also offers the SYBAScan tool, a web-based feature that helps growers identify the right soil mix from a simple photo, plus guidance and tips based on real growing conditions.

To explore Sybotanica’s range of soil blends, tools and growing resources, visit https://www.sybotanica.com.