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Propagation is your best friend as a plant parent. It's a free way to make more of the plants you already have, and watching new roots grow is so much fun! But there's more to it than sticking a pothos in a glass of water, not to mention that if you get the humidity wrong, you’ll get mold. So I invited over my go-to propagation nerd, Lindsay Sisti, to guide us through the different ways you can propagate successfully. She’s a propagation expert, plant breeder, and author of The Ultimate Guide to Houseplant Propagation. She’s been in the podcast before, and we've both survived mold cleanup in our own homes. Listen in!

 

In this episode, we learn:

• [02:22] Welcome back, Lindsay, my propagation nerd and friend of the pod!
• [04:28] What tropical houseplants are found in the rainforest?
• [06:00] Why your heating/AC sucks the humidity out of your home
• [10:00] Why growing houseplants indoors in Florida is hard!
• [10:56] When does humidity become a big aspect of plant keeping? (common plants vs. the divas)
• [14:51] Experience the richness of single-origin honey with 3x more antioxidants with Manukora!
• [16:36] Why filling your house with humidifiers isn't realistic
• [17:45] Lindsay's black mold nightmare in her 100-year-old home!
• [21:20] How humidity travels through your HVAC and grows mold where you'd never expect
• [23:29] Humidity hacks that fail (sorry!)
• [25:09] Why misting is mostly pointless and when it causes problems
• [28:31] IKEA grow cabinets 101: the MILSBO, Rust-Oleum, and building your glass box
• [33:40] Choosing grow lights: Barrina, Monios, and T8 vs. T5
• [35:53] Why you need fans and airflow (transpiration and guttation explained)
• [40:18] What prop boxes are and why they root plants better than a glass of water
• [43:21] Building a prop box (containers, sphagnum moss, and the “wrung-out sponge” rule)
• [46:30] Lindsay's layered setup!
• [49:44] Do you really need to “burp” your prop box?
• [52:31] How to rebuild Raffi the Rhaphidophora from node cuttings
• [58:16] Should you let cuttings callus first? Variegated vs. non-variegated
• [1:01:16] Mold vs. algae, and the diluted hydrogen peroxide fix
• [1:03:18] Final steps: lid on, into the window, and when to transplant
• [1:06:56] Can you crowd the nodes?
• [1:08:11] Why are prop boxes low stakes?
• [1:09:43] Where to find Lindsay and her propagation book!
• [1:11:21] Update: how Raffi's prop box actually turned out

 

 

Order my book!

Growing Joy: The Plant Lover's Guide to Cultivating Happiness (and Plants) by Maria Failla, Illustrated by Samantha Leung

 

 

Why Humidity Matters for Houseplants

Lindsay lives in the Midwest. The winters are freezing and summers are hot, so her home runs heating/AC almost year-round.

That dries out the air fast.

She noticed it right away: stick a pothos or monstera cutting in water, and it just wasn't happy. Her tropical plants needed more humidity to survive.

Tip: Grab a hygrometer so you actually know your numbers.

 

 

What Tropical Houseplants Actually Need

Your monsteras, philodendrons, and alocasias come from the rainforest, where humidity sits around 70-90%.

It's misty and warm, and it rains on and off all day. If you bring those plants into a dry home, they struggle. And if you take a cutting with no roots, it's even worse.

For comparison, our body is happy at 30-60%. Your plants want way more.

 

 

When Do You Really Need to Worry About Humidity?

Most of the time, you don't. Plants sold at garden centers and big-box stores are usually “hardened off,” and they're fine at normal home humidity (40-50%). Like green monsteras, ZZ plants, and snake plants.

Humidity only really matters in three cases:

1. Thin- or fuzzy-leafed rainforest plants (fuzzy begonias, thin alocasias) that can't handle dry air.
2. Rare plants from specialty sellers that start wilting a few days after you get them home.
3. Propagations – cuttings have no roots, so their leaves rely on moisture in the air to stay firm.

 

 

What Doesn't Work: Pebble Trays, Grouping, and Misting

I know you've probably seen a lot of humidity hacks on the internet, or probably heard some from other plat parents. Unfortunately, some of those hacks are not as effective as promised. Like these:

• Pebble trays – barely raise humidity and you mostly get slimy algae
• Grouping plants – creates a “microclimate,” but humidity effect is very minimal
• Misting – in a dry home, the water just evaporates. Worse, in a closed cabinet, water sits on the leaves and can cause fungal/bacterial problems

If you love misting, do it on your moss poles (they always need moisture) or use it to wipe dust off leaves.

 

 

Setting Up an IKEA Grow Cabinet

An IKEA grow cabinet is basically a big glass terrarium that keeps humidity in without soaking your home. Here's what you need:

• A glass cabinet – metal ones (like IKEA's) are preferred over wood because they won't rot from moisture
• Rust-Oleum paint on the metal, especially the bottom, to prevent rust from water buildup
• Shelves – swap the originals for wire or acrylic shelving, or hang plants with hooks
• Grow lights – two-foot T5 or T8 LED strips (Monios and Barrina are common budget brands) placed at the top of the cabinet
• Fans – a small waterproof fan on each level keeps water from sitting on the leaves. Search “IKEA cabinet fans” on Amazon.

 

 

Setting Up a Prop Box

A prop box is just a clear container you root cuttings in. Here's what goes in it:

• A clear container – smallest useful size is a tall plastic shoebox
• A drainage layer -1-2 inches of perlite or LECA on the bottom to catch extra water
• Moist sphagnum moss on top – add moss on top, hydrated until it feels like a wrung-out sponge (moist, not dripping). Too much water means too little oxygen, which causes rot. The layer should be thicker for plants with bigger root systems
• Leave air space above the substrate so new shoots have room to grow

About “burping” (lifting the lid to let in air): you don't have to, but it happens naturally when you check on your plants, which you should do every week or two anyway.

 

 

How to Deal with Mold in a Prop Box

First, know the difference: green fuzz on the moss is usually harmless algae. White mold is what you should keep an eye out on. Still, it’s a normal thing.

To handle it:

• Remove the moldy spot and swap in fresh sphagnum moss.
• Spray diluted hydrogen peroxide (1 part peroxide to 4 parts water) on any mold you see.

Best prevention: start clean (sterile tools, clean hands) and check your box every week or two. If a stem rots, pull it and spritz the area.

 

 

Keep the Stakes Low

Again, this is supposed to be fun! Every plant influencer (Lindsay and I included) has started a propagation and forgotten about it until it dried up or rotted.

My own Raffi box was proof where I cut everything up right before a move, left the pieces in a hot car, and fried them. It happens. So give yourself grace and enjoy watching a clipping burst into new life!

 

 

 

Mentioned in our conversation:

• The Ultimate Guide to Houseplant Propagation by Lindsay Sisti
• IKEA MILSBO
• Barrina Grow Light
• Monios-L Grow Lights
• LECHUZA-PON

 

 

 

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