The right philodendron selloum soil mix is chunky, airy, and drains fast while still holding steady moisture. Get that balance right and your tree philodendron will push out huge, deeply cut leaves. Get it wrong and you’ll see yellowing, soggy roots, and fungus gnats.
In this guide, I’ll share the mix I recommend, what each ingredient does, and how to pick a pot that helps instead of hurts. You’ll also learn when to repot and how to spot soil trouble early.
What Selloum Roots Need
Selloum roots need air, steady moisture, and fast drainage, all at the same time. A dense, peaty soil can’t do all three, so a chunky blend with orchid bark and perlite works far better.
Air Around the Roots
Philodendron selloum, now called Thaumatophyllum bipinnatifidum, is a big aroid in the family Araceae. Like its relatives, it has thick, fleshy roots that need oxygen to stay healthy.
When soil packs down tight, air pockets disappear. Roots sitting in airless, wet soil start to rot. That’s why I always add chunky materials that keep the mix open.
The two products I’d reach for first are:
- Orchid bark: Medium-sized fir or pine bark chunks that create big air gaps and slow down compaction.
- Perlite: Lightweight white volcanic granules that improve drainage and keep the mix fluffy.
You’ll find both in the potting or orchid section of most garden centers. Coarse perlite is better than the fine, dusty kind.
Steady Moisture, Never Soggy
Here’s the tricky part. Selloum likes steady moisture, but it hates soggy soil. It wants a mix that holds some water and lets the excess drain right through.
A good mix stays lightly damp a few days after watering. It shouldn’t feel muddy or stay wet for a week. Potting mix and coco coir give you that moisture-holding side, while bark and perlite handle drainage.
The Right pH and Nutrients
Selloum grows well in soil with a pH of about 5.5 to 7.0. That’s slightly acidic to neutral, which most standard potting mixes already fall within.
This plant is also a heavier feeder in summer. A mix with some organic matter gives roots a little nutrition between feedings. Still, fertilizer does most of the work, which I’ll cover later.
The Best Soil Mix Recipe
The best philodendron selloum soil mix is roughly equal parts potting mix, orchid bark, and perlite, with optional coco coir. It’s simple, cheap, and easy to adjust for your home.
My Basic Recipe
Here’s the recipe I recommend for most indoor selloums:
- 1 part quality indoor potting mix
- 1 part medium orchid bark
- 1 part coarse perlite
- Optional: ½ part coco coir for extra moisture retention
Mix everything in a bucket or on a tarp. Lightly dampen it before potting so it’s easier to handle and doesn’t repel water at first.
| Ingredient | Amount | Main Job |
|---|---|---|
| Potting mix | 1 part | Holds moisture and nutrients |
| Orchid bark | 1 part | Adds air pockets, slows compaction |
| Perlite | 1 part | Improves drainage |
| Coco coir (optional) | ½ part | Extra moisture retention |
A “part” can be any measure you like. Use a cup for a small plant or a bucket for a large one. What matters is the ratio.
Adjusting the Recipe for Your Home
Every home is different, so tweak the mix to fit your conditions. If your house is dry and warm, the mix may dry too fast. Add a bit more coco coir or potting mix.
If your home is cool, humid, or a bit dim, the soil will stay wet longer. In that case, add extra bark and perlite. Less water-holding material means less risk of root rot.
Your watering habits matter too. If you tend to overwater, go chunkier. If you forget to water, add a little more coir.
Mix for Outdoor Selloums
In warm areas, roughly zones 9b to 11, selloum grows outdoors in the ground. There, it does best in rich, well-drained soil with compost worked in.
Dig compost into the planting area to improve both drainage and fertility. Avoid low spots where water pools after rain. Heavy clay should be loosened and amended well before planting.
Ingredients and What Each One Does
Each ingredient in the mix has one main job: holding water, adding air, or improving drainage. Knowing what each does makes it easy to fix a mix that isn’t working.
Potting Mix and Coco Coir
Potting mix is the base. It holds moisture and gives the blend some body. Pick a general indoor potting mix, not garden soil, which is far too heavy for containers.
For more on picking a good base, see my guide to the best soil for indoor plants. The same basics apply here.
Coco coir is made from coconut husk fiber. It holds water well, rewets easily after drying out, and doesn’t break down quickly. It’s a nice optional add-in for thirsty plants or dry homes.
Orchid Bark
Orchid bark is the backbone of a chunky aroid mix. Its large pieces leave gaps for air and water to move through. Roots grip the bark, too, which helps anchor a heavy plant.
Bark breaks down slowly over a year or two. As it decays, the mix gets denser. That’s one reason regular repotting matters.
Medium-sized chunks, roughly ¼ to ½ inch, work best for most selloums. Very large chunks can leave the mix too loose for smaller plants.
Perlite and Other Optional Add-Ins
Perlite keeps the mix light and helps excess water drain fast. It doesn’t break down, so it keeps working for years.
A few other materials can play a supporting role:
| Add-In | What It Does | Use It When |
|---|---|---|
| Horticultural charcoal | Adds texture and air space | You want a chunkier mix |
| Pumice | Drainage, heavier than perlite | Tall plants tip over easily |
| Worm castings | Gentle organic nutrients | You want a richer blend |
| Compost | Nutrients and structure | Planting outdoors |
Keep add-ins modest. A small handful of worm castings or charcoal is plenty. Too many extras can throw off the balance you’re aiming for.
Store-Bought vs. Homemade Mix
Homemade mix gives you the most control and usually works best for selloum. Store-bought aroid mixes can work well, but plain bagged potting soil alone is too dense.
Pros and Cons of Store-Bought Mix
Bagged “aroid” or “chunky” mixes are convenient. They’re ready to use and often contain bark, perlite, and coir already.
The downside is cost and consistency. Some bags are mostly fine material with only a little bark. Others are very loose and dry out fast. Always open the bag and look before you pot.
| Option | Pros | Cons |
|---|---|---|
| Store-bought aroid mix | Convenient, ready to use | Pricier, quality varies |
| Plain potting soil | Cheap, easy to find | Too dense on its own |
| Homemade chunky mix | Customizable, affordable in bulk | Takes a few minutes to mix |
Why I Prefer Homemade
My advice is to make your own. Buying potting mix, orchid bark, and perlite separately lets you adjust the ratio for your plant and home.
It’s also cheaper over time, especially with a big plant. Selloums can grow very large, and a big pot takes a lot of soil.
How to Upgrade a Bagged Mix
If you already have regular potting soil, you don’t have to toss it. Just amend it.
- Start with the bagged potting soil as one part.
- Add one part orchid bark.
- Add one part perlite.
- Mix well and check the texture.
The finished blend should feel loose and crumbly. When you squeeze a damp handful, it should fall apart instead of forming a tight ball.
Pots and Drainage
The best pot for selloum has drainage holes and is only slightly larger than the root ball. Even a perfect mix will fail in a pot that traps water.
Drainage Holes Are Non-Negotiable
Always use a pot with at least one drainage hole. Without one, water collects at the bottom and rots the roots.
If you love a decorative pot with no hole, use it as a cover pot. Keep the plant in a plastic nursery pot inside it. Empty any water that collects in the outer pot after watering.
Skip the layer of gravel at the bottom. It doesn’t improve drainage. It actually raises the wet zone higher into the pot, closer to the roots.
Choosing the Right Material
Pot material changes how fast your soil dries.
| Pot Material | Drying Speed | Best For |
|---|---|---|
| Terracotta | Fast | Overwaterers, humid homes |
| Plastic | Slow | Dry homes, forgetful waterers |
| Glazed ceramic | Slow to medium | Heavy, top-heavy plants |
| Fabric | Fast | Strong root growth |
A mature selloum gets heavy and top-heavy as its trunk leans with age. A wide, heavy pot