Do Terrarium Plants Stay Small?


assorted small terrarium plants on the table at indoorplantsforbeginners.com

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Choosing plants that are the right size for your terrarium doesn’t have to be complicated. Once you know a few of the basic requirements including the size of your terrarium it’s much easier to choose the proper plants to grow inside it. Obviously the plants will all need to start off small to comfortably fit inside your terrarium, but do terrarium plants stay small?

Whether terrarium plants stay small depends on the species. Certain plants are always tiny while others start that way and become larger later. However, research has shown that by growing a plant in a bigger environment versus a smaller one, more growth occurs.

I want to get into a lot more detail about what causes some terrarium plants to stay small compared to others, so I suggest you keep reading. This article will help you choose the right plants for a small indoor terrarium that will stay as picturesque and tiny months from now as they are today!

Terrarium Plant Size: What Influences It?

A terrarium is a great way to start a tidy, contained indoor garden just about anywhere, whether that’s in your home or apartment or even at work. Yet if you’re choosing to go the terrarium route, it’s likely because you have certain expectations about plant care, right?

You anticipate your plants will only get to about yae high, and perhaps some will. Others though could extend beyond the confines of the angular glass terrarium walls to get more space.

That’s why I now want to delve further into whether a terrarium plant stays small because it’s just that way naturally or because you put it in a terrarium versus a pot.

Plant Species and Size

When buying a plant of your own, think of it less as purchasing a home accessory and more like adopting a dog or cat. You need to put just as much research into your decision rather than blindly making a choice that you might later regret.

Let’s say you wanted to adopt a dog. With more than 200 breeds recognized by the American Kennel Club, you can choose a nice, normal-sized dog, a huge breed, or even a dog that fits in your pocket.

Most dogs–except for the very large breeds–start off as cute, tiny, handheld puppies. Then they grow, and in a matter of months, they’re on their way to reaching the size their breed standard calls for.

Okay, but you’re not adopting a dog. You’re buying a plant. Yet it’s not all that different.

Plants, like dogs or even cats, will start small if you buy yours when it’s young enough. Then, through time and care, the plant begins to grow. How big will your plant get? That depends on the species.

Let’s use one of the small terrarium plants I recommended in my last article as an example, the air plant. If you recall from that article, I mentioned that air plants may be as little as 2 inches and as large as 7 feet. In this case, it’s all about which air plant variety you choose.

The Red Jonatha is a large air plant with stunning deep red foliage. The Tricolor Melanocrater is another sizable air plant while the Medusa has thick, curvy appendages almost like a succulent. It too is quite big.

The Stricta Hard Leaf air plant is probably the one you saw in pictures that made you think, “yes, this is the perfect small plant for my terrarium.” If that’s the air plant variety you buy, you’d never have to worry about it growing too large for the terrarium.

Yet if you purchased another air plant instead because you thought all air plants are the same, you would soon find out you’re sorely mistaken. That’s why I advocate for at least a minimal amount of research before you buy any plant.

You need to ask questions at the gardening supply store too. It’s okay to admit you don’t know everything. Learning new information makes you a better indoor gardener!

When shopping online, be even more inquisitive still. If a listing doesn’t make clear what kind of plant you’re getting in terms of size and maturity, get in touch with the company and ask. You’ll always be glad you did.

Enclosure Size

Let’s say you goofed and bought a plant that will grow bigger than the confines of your terrarium allow. Will the tight environment keep the plant small?

Yes and no. You can’t make a miniature version of a large plant by putting it in a terrarium, as that’s just not how it works. Yet there is data out there that indicates that plants will grow larger if they have more room to do so.

That information comes from a 2012 report from the journal Society for Experimental Biology. A group of plant scientists assessed the way a plant’s roots will lay themselves out over time according to the size of their environment using 3D MRI root scans.

To supplement their research, the scientists reviewed more than 60 studies on different plant species and how large they would grow depending on the size of their containers. Some of the plants that were in this body of research include cotton plants, wheat, cacti, pine trees, corn, and tomato plants.

What did the scientists find? The plants that grew in pots that were at least twice bigger than average had huge growth gains. These plants were 43 percent bigger than those houseplants grown in smaller containers.

The scientists attributed the reduced growth of the plants in the smaller pots to slowed photosynthesis.

Okay, so what does this tell us? That photosynthesis occurs at a lesser rate for plants grown in small containers than large ones, and that these plants will be more than 40 percent smaller than plants grown in a larger container. Well, at least according to the information from the study.

This may sound like a very promising argument to just put a plant of whatever size in your terrarium since it won’t grow as large anyway. Yet it likely will. 

I’m assuming you’re not neglecting your plants, so you’re providing them water, sunlight, maybe humidity if they need it. These things all encourage growth, not impede it. Thus, your plants will grow.

In a small terrarium, you don’t want any one plant dominating the others. If an original plant hogs up all the space, limiting how much the other plants in the terrarium can grow, the other plants will receive less sunlight and water as the larger plant sucks up these resources.

Before you know it, the other plants begin dying and your terrarium features but one plant.

Want Your Terrarium Plants to Stay Small? Choose Your Plants Selectively

Similar to the way some dogs have been bred to remain puppy-sized forever, many indoor plant species won’t grow large. For a small terrarium, you want to look into houseplants that are 6 inches or smaller.

I once again recommend you check out my list of the best small plants for open terrariums. From hen and chicks to living stones, Venus flytraps, mini African violets, and zebra plants, that list is full of variety for a visually appealing terrarium.

If you want to add any plants to your small terrarium outside of the ones on my list, then look up the plant’s height (and width) at maturity. Remember that maturity is different from one plant to another. Some plant species will reach maturity after a few months.

In the case of Marimo moss balls, it takes anywhere from 8 to 15 years.

Plants for Mid-Sized and Larger Terrariums

Any plant that exceeds 6 inches would do best in a medium terrarium and those plants that are 12 inches or more should be in a large terrarium. To wrap up, I thought I’d share a list of terrarium plants that do better in bigger environments.

Stonecrop

The stonecrop is a succulent that starts at about 6 inches but reaches heights of 24 inches at maturity. It’s also a spacious grower, with average widths of 12 to 24 inches. Anything smaller than a large terrarium won’t be able to contain the stonecrop.

To grow your Sedum, provide full sun. If you notice your stonecrop is leggy, that’s because you haven’t given the plant enough sun. Moisten the soil fully but don’t water the stonecrop again for a while. Remember, it is a succulent, so it will keep the water you give it for a while. Avoid exposure to temperatures over 90 degrees Fahrenheit or your stonecrop’s leaves will burn.

Butterworts

Do you want a carnivorous plant for your larger terrarium akin to the Venus flytrap? Try the Pinguicula or butterworts. This plant’s leaves are sticky so insects that land upon the leaves will get stuck and then become the butterwort’s lunch. Each leaf can grow to lengths of 6 inches to catch even more flies and other bugs!

Bright, indirect sun and even some partial shade will keep your butterworts healthy. Use well-draining soil and ensure the soil doesn’t get bone-dry. In the winter, prune your butterworts so you can see more leaf growth come the spring. You could enjoy fewer bugs around the house for your troubles.

Sundews

Your butterworts would pair well with sundews, a second carnivorous plant to add to a bigger terrarium. The average size of a sundew is 10 inches. With more than 194 species of Drosera, what your sundew looks like will vary. Some resemble pink flowers with rosettes and others long, green vines.

All sundews are covered in glandular tentacles that release secretions to entrap prey. Enzymes within the plant can digest the insects the sundew catches while its sessile glands allow for optimal nutrient absorption.

Like butterworts, sundews require moist soil around the clock. Avoid using tap water for sundews, choosing mineral-free water instead. If your sundew is colorful already, full sun will maintain its color and sometimes make it more apparent.

Prayer Plant

Here’s a stately plant for your terrarium, the prayer plant. Growing between 10 and 12 inches tall with a width of up to 18 inches, the prayer plant will need considerable room in your large terrarium.

Its appealing leaves will give you a lot to admire. Some varieties of prayer plant feature leaves flecked with dark patches while others have neon pink veins. Think of the prayer plant as a nerve plant but for bigger terrariums.

Just keep your prayer plant away from your terrarium succulents, as the Maranta leuconeura grows best in partial shade to full shade depending on the variety. It too likes well-draining and moist soil, so water it when the soil begins drying out. In the spring, your prayer plant may grow white flowers, but this doesn’t happen all that often. Still, it’s something to aspire to!

Spider Plant

Like the prayer plant replaces the nerve plant, your spider plant will act as a nice stand-in for the air plant in a bigger terrarium. Its average height is 12 inches, but it can get wide and bushy.

Use distilled or filtered water for the spider plant, anything that’s fluoride-free. Maintain slight soil moisture but nothing soaking. Room temperature is a-okay for the spider plant, as is bright, indirect light.

Golden Pothos

How about some trailing plants for your terrarium? The golden pothos is a suitable pick, what with its beautifully variegated leaves in a lovely heart shape.

While a golden pothos may start off small, it’s one plant you’ll need to prune more often than others, especially if you’re growing it in a small space such as a terrarium.

Since it’s a vine, the golden pothos grows longer than it does wide, sometimes reaching lengths of 10 feet. I doubt it will get that big in your terrarium though, as sizes of 4 to 8 inches are much more common.

The golden pothos requires bright, indirect light with periods of shade. Keep those periods short if you want your golden pothos to retain its variegation. You’ll know it’s time to water your pothos because the soil will be dry to the touch at least an inch deep.

Fred Zimmer

I'm a lover of plants, animals, photography, & people, not necessarily in that order. Currently, I'm focused on photographing indoor plants & chachkies. I write & rewrite articles about creating an environment where indoor plants can thrive. I'm good at listening to music but bad at shopping to muzak.

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