Open vs closed terrariums: which should you build first?

The open vs closed terrarium question comes up constantly. Here’s the honest comparison, then my recommendation for what to build first.

Closed terrariums (with a lid)

The basics: Sealed glass container with a lid. Water cycles inside the jar — evaporates, condenses on the glass, runs back down.

Pros

• Almost no maintenance after the first month
• Perfect for humidity-loving plants (moss, ferns, fittonia)
• Forgiving of beginner mistakes (overwatering, underwatering)
• Looks dramatic (foggy glass, condensation)
• Hardest to kill once established

Cons

• Limited plant selection (no succulents, no cacti, no plants that need dry air)
• Risk of mold if air circulation is bad
• Can get too humid and rot plants
• Smaller plant palette = less variety

Best for

Moss-heavy builds, tropical mini-gardens, “set and forget” projects, beginners who want a near-guaranteed success.

Open terrariums (no lid)

The basics: Open glass container, no lid. Behaves like a tiny pot.

Pros

• Can grow succulents, cacti, and air plants
• More plant variety
• Easier to access for maintenance
• Better air circulation (less mold risk)
• Looks more like a miniature garden

Cons

• Needs regular watering (every few days to weekly)
• Loses humidity fast in dry rooms
• Smaller plants dry out fast
• More frequent maintenance
• Higher failure rate for beginners

Best for

Succulent arrangements, dry-climate plants, builders who don’t mind weekly maintenance.

The honest comparison

	Closed	Open
Maintenance	Low	Medium-High
Plant variety	Narrow (humidity lovers)	Wider (incl. succulents)
Beginner success rate	High	Medium
Risk of mold	Medium	Low
Risk of drying out	Low	High
Visual drama	High (fog, condensation)	Medium

What to build first

For 80% of beginners: closed.

Why? Closed terrariums are more forgiving. If you forget to water, the system handles it. If you overwater, you can air it out. If you pick the wrong plants, the high humidity usually saves you for a few weeks.

Open terrariums expose every mistake. Forget to water for a week in dry indoor air and your succulents are crispy.

Once you’ve kept a closed terrarium alive for 6+ months, try an open build. You’ll have learned the basics and can handle the higher maintenance.

The exception

If you specifically want succulents or cacti, skip closed entirely. These plants WILL rot in a closed jar. Build open from the start.

Can you mix both?

Sort of. A “mostly closed” build with the lid propped open slightly can work as a transition between the two. This is good for plants that like humidity but not full saturation (some peperomias, certain begonias).

What to do with this info

1. If you’re building your first terrarium ever: Start closed.
2. If you only want succulents: Start open.
3. If you’ve never built either: Build one closed jar this month, one open jar next month. See which you enjoy maintaining more.
4. If you want both: Build one of each, side by side. Compare.

See our closed terrarium build guide or our [open terrarium guide (coming soon)].

Questions? Hit the Discord.