How to Make a Plant Propagation Box

Learn how to make a plant propagation box to create a little greenhouse that’s perfect for creating the conditions necessary to root plants.

How to make a plant propagation box

Hey all. It’s been plants out the wazoo over here lately. Heads up, you should expect that going forward! 🙂 It’s spring, meaning it’s propagation and plant season. So what better time than now for me to share my moss propagation box setup?

What’s a plant propagation box?

A plant propagation box is basically a way to create a small greenhouse and keep humidity and moisture levels high. Which is great for propagations and root development. They are typically made out of clear storage containers, but I’ve seen people use a ton of different things for them (old clear plastic takeout containers are common).

A long time ago, I wrote about my plastic clamshell salad container propagation box. You know, the ones that the mixed greens come in? I usually didn’t keep the lid on it, but I kept it in Ramona’s bathroom window. It still did an amazing job of helping plants root.

But now I use a clear shoebox-sized storage bin with a lid that latches on for most of my propagations. It’s the perfect size for a windowsill so I can ensure it gets great light. (I also have a smaller plastic container that used to hold lunch meat, and I’ll talk about that one too.)

Here is what I use for my moss propagation box setup:

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• Clear plastic bin and lid, like this kind
• Sphagnum moss
• Perlite
• Worm castings
• Mixing bowl
• Spray bottle and water
• Rooting hormone powder

And here’s how to make a plant propagation box.

Step 1: Decide on your approach

You can either dump all of your potting medium into the box and set your cuttings in that, letting them root freely. Or you can fill the bin up with smaller containers to keep each individual cutting’s roots contained.

Each has pros and cons. If you just fill your bin up with your potting medium and let your cuttings root freely, you’ll surely be able to fit more. However, the roots might get tangled, and it might be hard to monitor root development on specific plants.

Therefore, I chose to use small containers for each of the cuttings in my shoebox-sized propagation bin. The little plastic cups that sides come in at Chipotle are PERFECT for this! They are a great size. Oh, and I use old plastic containers from Ramona’s little slimes, lol. I try to reuse everything.

I did have some leftover moss mixture though, so instead of tossing it, I grabbed an old plastic lunch meat container to be a prop box too. This one has two different kinds of hoyas, and it’s much smaller. So I decided to ditch the smaller cups for that one and just dump the medium in the bin.

Step 2: Mix the moss-based medium

There are endless different recommendations for what to use as a potting medium to room propagations. It depends a lot on the plant, too. I have had a lot of luck with sphagnum-moss-based mediums, so I’ll share my mixture. It isn’t right or wrong. It’s just an option 🙂

I would say that my mixture is about 50% sphagnum moss and 50% perlite. Too much moss can get soggy and can potentially rot your plant. (See my post all about how to propagate cuttings in sphagnum moss for more, too.) The perlite helps keep things breathable.

I put the moss in a bowl and soak it with water. Then I wring out all of the water I possibly can. The moss should just remain damp. Seriously, squeeze EVERYTHING out that you possibly can. Then mix in the perlite. The perlite tends to fall to the bottom while mixing.

I also add in a handful of worm castings for some extra nutrients. Not too much—just enough. I mix that in thoroughly. No need to add extra water. 

Step 3: Set up the box

Next I fill my little cups with the mixture, dip my cuttings in a bit of rooting hormone, and nestle them down into their cups for the long haul. I arrange them in the box, put on the lid, and call it a day!

If you aren’t using cups, you can just dump the propagation mixture in, add your cuttings, and call it a day. That’s what I did with my lunch meat box.

Step 4: Add the lid and wait

Once I was finished filling my boxes up, I put the lid on and set them in the window. The humidity gets SUPER high in the boxes, which is great. But you also do want some air flow, and you want to be mindful of rot.

After a few days, I take out the box and check on everything. I let the box sit open for a bit to help with air flow. Then I check all of the cuttings, as well as how damp the mixture is. It will probably stay pretty damp with the lid on. 

When it starts drying out, you can use a spray bottle to dampen it again. I do a check every few days just to make sure things are looking good. I haven’t had any problems with rot using this setup.

What about air holes?

If you want to use a hammer and nail, you can poke a few holes in the lid to allow a bit of air in. I haven’t done that, but I know some people do. I think it depends a lot on moisture levels (how often you want to dampen everything again) and the plants you’ve got in there!

Here’s what I have in my boxes right now

In my little lunch meat box, I currently have hoya linearis and hoya australis (some kinda yucky cuttings that I pruned off of my main plant and didn’t have the heart to throw away). In the main shoebox-sized propagation box, I have these plants:

• Philodendron grazielae
• Scindapsus treubii moonlight
• Hoya pubicalyx splash
• Scindapsus pictus exotica and silvery Anne
• Hoya carnosa Chelsea
• Scindapsus jade satin
• Pothos cebu blue
• Pothos global green

Pin my tips about how to make a plant propagation box!