How to Make a Terrarium Last

I want to be honest with you about how long you can expect your terrarium to last and thrive.  Many blogs show fast and easy terrarium crafts in tiny glass vessels and bubbles, but they rarely show you what a tiny terrarium will look like after three months.  Probably dried out or moldy.  Tiny terrariums are cute if you think of them as a cut flower arrangement.  But part of the thrill of building terrariums is chasing the lasting terrarium, which sometimes means restarting, trying new combinations of plants, soil, and containers - until the ecosystem clicks and then plants thrive.  My longest-lasting terrarium was built in a wine jug and lasted about three years.  It looked a lot like the photo above from thedebrief.uk. Note the deep moss roots, and appearance of algae type stuff in the bottom layers of the soil. This is what a slice of the outdoors looks like under glass!

Secrets to a Long-Lasting Terrarium

1. Use a large enough glass container. A general equation seems to be, the larger the container, the better the chance the terrarium has to thrive.
2. Use an adequate amount of soil. If plants are to grow, they will need some space.
3. Use healthy plants and moss that have been inspected for insects and washed if needed. Select plants that have similar light and water requirements (e.g. woodsy ferns with moss, succulents with cacti.) See 19 of the most popular terrarium plants.
4. Keep up with terrarium maintenance! This includes managing water and temperature levels (e.g. water occasionally and don't leave it in full sun all day).  You might need to put a lid on your terrarium occasionally to help keep water in the system.  You might need to remove dead leaves or scrub the sides of the container of algae fuzz.
5. If all else fails, try again. Don't be afraid to restart your terrarium if mold takes over, plants die, or insects infest.  Shake it all out, scrub out the container with water and a bit of bleach, and try again when it is dry.  Fresh plants and soil!

How long has your healthiest terrarium lasted? 53 years?

How to Water an Air Plant Terrarium

Tillandsia aeranthos in collectie Eric J. Gouda

Air plants or tillandsia make an ethereal addition to an ornament terrarium or hanging terrarium, and are among the most common terrarium plants.  But how to water these spiky beauties?  Traditional air plant care indicates a periodic soak in water to allow for watering.  However, it may be difficult to remove an air plant from an ornament terrarium with a small opening.

Shari Petrucci from the Western Mass Masters Gardeners Association shares a suggestion at Mass Appeal:

"If your air-plants are in a small terrarium and you are unable to remove them for watering, we recommend misting them through the opening once weekly. This method can also be used for our hanging globe terrariums, wall pockets, and apothecary terrariums. Pay close attention that your plants are getting adequate moisture, but are not sitting in water within any terrarium."

Remember that using distilled water in terrariums can reduce the amount of mineral deposits that develop on the glass.  Be sure to visit Air Plants 101 at Mass Appeal to learn more about air plant care.

1012 Terra Terrariums Operate Without Soil

Image via Gizmodo

If you'd prefer the pristine view of your terrarium plant sans soil, check out these fascinating hydroponic terrarium vessels from 1012 Terra.  I wonder if the plants would survive for long?

Q & A: Ants in Terrarium

Image from Wikipedia Commons, by Fir0002/Flagstaffotos

I've never had the misfortune to find ants in a terrarium - let alone an entire colony moving in!  Does anyone have any ideas for Natalie K.:

"I have a 2.5 gallon desert terrarium that sits on my window sill It has a screentop lid to keep the humidity low and allow an extra light to sit on top. Ants have moved in though and are nesting in the soil. I don't know how long they've been there but I just noticed them moving pupae in. I dumped a bunch of water in(there's a layer of marbles and moss to allow drainage) and that seems to have scattered them out for now. How do I get them out for good??? Short of dumping the entire thing and starting over?"

See the solution to the ants in a terrarium.

Help, I Overwatered: Removing Water from a Terrarium

You've gone and overwatered your terrarium and all the signs are there: condensation on all the interior surfaces, drowned plants and possibly the appearance of algae scuz.  I have one trick for you to try.

Twist up a paper towel or two and dangle them into your terrarium until it just touches the surface of the soil.  Paper towels are mega absorbent and thanks to capillary action - water will travel up the surface and out of your terrarium.  Think of it as the opposite of using a water wick to water houseplants.

Leave the paper towel wick for a few hours and then toss the sopping thing out!

Mixing Soil for a Terrarium

I generally recommend a ratio of about two parts potting soil to one part sand for a terrarium.  I find this mix promotes drainage but still retains enough moisture to keep humidity-loving plants like ferns and moss happy.  Watch out for potting soil loaded with fertilizer (like the one in the photo).  You don't want terrarium plants kicking into hyper-grow mode and outgrowing your terrarium vessel.

Soil mix with water added

Only mix a little water into your soil mix prior to adding it to your terrarium.  Very wet soil will be difficult to add into a narrow-necked vessel and it is always easier to add more water to a terrarium than remove it later!

I'll be sharing an ultra-insider, expert tip to remedy an overwatered terrarium tomorrow so stay tuned!

53-Year Old "Bottle Garden" Terrarium!

The Daily Mail reports that David Latimer fashioned this terrarium out of a "ten gallon carboy, or globular bottle, which once contained sulphuric acid" and spiderworts in 1960, last watered it in 1973 and then sealed it up.   The entire system has been self-sustained for over 40 years!

This story seems to corroborate my hunch that, while we are all entranced with teeny-tiny terraria, the best vessels for creating an established ecosystem seem to be the big ones.   A Carlo Rossi 5 liter wine jug housed my longest-lasting terrarium.   Said wine jug terrarium also developed the algae bloom looking stuff in the soil layer like Mr. Latimer's behemoth. 

5 Tips from a Terrarium Pro

Jennifer Schultz Nelson is a horticulture education in University of Illinois Extension and apparently a savvy terrarium keeper who has shared a detailed, two-part article at herald-review.com on making top-shape terrariums.  I'll recap the five best tips but read both articles if you want a great overview of making and maintaining terrariums.

1. Plan on using 25% of a terrarium vessel for drainage material and soil mix.  Read more about the supplies you'll need to build the soil layers in a terrarium.      
2. Don't overwater your terrarium.  "If the walls are completely fogged up with condensation, open the terrarium and allow some of the water to evaporate for a day."
3. "A closed terrarium will likely not need watering more than once or twice per year."  That one is news to me!  I've never had a completely sealed up terrarium so I cannot attest to that fact based on my personal experience. 
4. Like many plants, you will need to occasionally prune or remove dead leaves.  "Prune plants by pinching out growing tips or using a small blade attached to a stick inserted through the container opening."  I've had minimal luck with the small-blade idea and prefer using very, very long scissors (specially purchased online).  This probably depends on the sturdiness of the plant in question.
5. And I've saved the best for last, as it an unfortunate truth of the terrarium hobby that I've mentioned before.

"Occasionally, plants may overtake a terrarium or die, making replacement necessary. It may be necessary to start over if plants are extremely overgrown and cannot be removed without disrupting the entire terrarium."

Whether a terrarium is overgrown, or fails - just like any other gardening experience - sometimes plants don't work out.  Read my five tips for starting a terrarium over again (the right way).

Choosing the Best Plants for a Terrarium Ornament

I always receive some questions about making terrarium ornaments during the weeks that lead up to the holidays.  Terrarium ornaments make wonderful gifts, conversation pieces or even tree decorations.  However - it is a small vessel in which to build a terrarium environment.  How can you ensure your precious project won't be a dud in a matter of days?  

The best advice would really be dependent on:

•  the type of ornament vessel you are using (does it have a hole in it or is it sealed?)
• Do you intend for the plants in your terrarium ornament to last beyond a couple of weeks?

If you are using the typical empty ornament that unscrews at the top and then results in a sealed environment - your best bet is to use an air plant or a succulent with a very small amount of soil.  The succulent is not going to be happy in the ornament environment indefinitely.  Read more about using an air plant for a terrarium ornament in my earlier post. 

If you are looking for a terrarium ornament to last you beyond the holidays - consider springing for a hanging terrarium vessel like the one pictured above, available from CB2.  This larger vessel would allow you to add more soil and the proper drainage layers, and the air hole would allow a plant to grow and extend beyond the dimensions of the container over time.  You could even select a plant that would fully utilize the air hole, such as a string of pearls succulent (photo from Inner Gardens).

Why You Should Use Distilled Water in Your Terrarium

Q: Does distilled water have significant advantages over boiled and cooled water?

A: Using distilled water in your terrarium reduces the accumulation of mineral build-up in your environment. If you choose to water your terrarium with tap water or boiled tap water, you may see a crust of mineral deposit form in your soil or on the walls of your terrarium vessel over time.  If you know your tap water is particularly hard or soft - I would recommend using distilled water in your terrarium as much as possible. 

Buy Air Plants (tillandsia) Online

My post last week about the Jellyfish Air Plants attracted quite a bit of attention.  While I love the ingenuity of that Etsy seller, the item doesn't look that hard to DIY.  If you are looking for a variety of tillandsia to jumpstart your next craft the site air-plants.com have a variety and some reasonably-priced combo packs.  The site also provides excellent information on how to water your air plant or tillandsia:

"You can also mist your plants as needed, in between watering but misting should not be used as a sole source of moisture. We prefer to use a dunking method when we water, and then every other week or so we will give the plants a longer soak for an hour or 2.  Always take care to gently shake any excess water off the base of the plants, as sitting water can cause rot and damage/kill the plant.  It is recommended that you water your plants in the morning, and leave them out of their containers in an area that they can dry within 4 hours.  Never let your Air Plant sit in water for prolonged periods of time!"

Operation Diagnose: Proper Temperatures for Your Terrarium

Condensation "fog" in terrarium soil.

Operation Diagnose:  I'm wrapping up the "Operation Diagnose" week with a combination of two questions I received this week that aim at the same topic: temperatures for terrariums.

Here are the questions from Nesting Ranch:

Question:  We could really use your advice as we're having just a dickens of a time with our terrariums.  The latest theories are:
a) our house doesn't get much light as the southern exposure faces dense woods and the windows are east and west facing... so we don't put them against the window or they could fry in the direct light, but elsewhere in the house isn't enough?
b) we like our AC temp set cooler than moss or ferns care for (75-77)?

And the question from reader Ian: I planted a terrarium. As soon as I added the soil moisture seemed to be between the dirt and the glass. It doesn’t look like condensation. It looks like fog.

TL:DR Answer: Terrariums need to be out of direct sunlight so they don't overheat and fry, but other than that they should be fine in regular indoor temperatures.    

For those of you that have some more time: read on...

Nesting Ranch, your indoor house temps are fine.  The beauty of terrariums is that they thrive in the temperatures that us humans prefer to keep in our homes.  The main temperature concern for terrariums is overheating.  What are symptoms of an overheated terrarium?  

An overheated, open-top terrarium could get dried out quickly - with bone dry soil and dried out plants.  An overheated, lidded terrarium would have wilted plants, excessive condensation on the glass, and the excessive appearance of steam or fog between the soil and the glass.



Please note the emphasis on "excessive."  The fog-appearance of water condensation around the soil and the glass is pretty normal if it looks like the terrarium pictured at the top of the post.

If you notice fog, I would caution you to track what times of day and how frequently you see the fog.  It is common for a terrarium to steam up when it is in direct sun (and it shouldn't be in direct sun all day - maybe 45 mins at most).  If you see the fog around the clock- your terrarium may be getting overheated due to being too close to a window or other heat source.  Overheating, in the long run, contributes to disease and plant rot.

With that said, terrariums will need sufficient indirect light.  They need to be kept in the general vicinity of a window but not right next to it and not anywhere that direct sunbeams are hitting them for too long of periods.

Operation Diagnose: The Best Soil for a Terrarium

Soil Mix by Nesting Ranch

Operation Diagnose:  This week I'll explore a variety of ailments that commonly afflict terrariums.  A reader contacted me a with a bevy of floundering terraria (with accompanying photos).  This affords a great opportunity for me to attempt to diagnose the problems and make suggestions - but I also encourage you to chime in and share suggestions or anecdotes in the comments!

Here is a brief summary of the questions from Nesting Ranch:

Question:  We could really use your advice as we're having just a dickens of a time with our terrariums. Some are open, others closed, some with ferns, some are just moss, some "wild" from the yard and some revived... none are doing quite well. Ferns are loosing leaves or turning black. Mosses are browning or yellowing. Just can't seem to pin-point why. 

Answer: Today I'd like to discuss soil mixes for terrariums.  

TL:DR Answer: I recommend a 50/50 potting soil and sand mix for terrariums.

For those of you that have some more time: read on...

If you are using a larger terrarium vessel like an aquarium, you may want to increase the ratio of soil you mix into your substrate.  This will ensure your larger plants get more nutrients as time goes on.

Nesting Ranch, it appears from your photos that you used a potting soil mixed with peat?  I use soil mixed with sand to ensure that I can water frequently and have it drain through the soil quickly.  As the environment is so small and enclosed, I do what I can to make sure roots aren't standing in overly dry soil or damp soil.  Here is my brief spiel on soil from my how to, Adding Soil Layers:

"Mix one part potting mix with one part sand to ensure proper drainage. Add distilled water to make damp but it is easier to transfer to terrarium when it is dry. Remember - you can always add more water to your final terrarium but it is difficult to remove!  You should have enough soil to fill about 1/4 to 1/3 of your terrarium container. I would recommend using about 1/2 of the portion you have set aside for your terrarium and then adding the rest after you have planted your largest terrarium plants. Add the soil by scooping spoonfuls into your paper cone and tamping down with a skewer.   Once you have layered your dirt into the terrarium you'll want to mist down the soil.  Soil will need to remain damp throughout the life of your terrarium to support your plant growth."

According to Wikipedia, "The most important property of peat is retaining moisture in soil when it is dry and yet preventing the excess of water from killing roots when it is wet."  That doesn't sound inherently bad for a terrarium, but the part about retaining moisture in the soil makes me hesitant of its application to terrarium life.  Yes, plants like moss and ferns need a lot of moisture.  However,  a healthy terrarium has an interior water cycle; water moves through the soil, evaporates into condensation on the sides of the vessel, which again spill down into the soil in a cycle.  

Has anyone had good luck using peat or sphagnum soil mix in terrariums?

Operation Diagnose: To Lid or Not to Lid

Terrariums by Nesting Ranch

Operation Diagnose:  This week I'll explore a variety of ailments that commonly afflict terrariums.  A reader contacted me a with a bevy of floundering terraria (with accompanying photos).  This affords a great opportunity for me to attempt to diagnose the problems and make suggestions - but I also encourage you to chime in and share suggestions or anecdotes in the comments!

Here is a brief summary of the questions from Nesting Ranch:

Question:  We could really use your advice as we're having just a dickens of a time with our terrariums. Some are open, others closed, some with ferns, some are just moss, some "wild" from the yard and some revived... none are doing quite well. Ferns are loosing leaves or turning black. Mosses are browning or yellowing. Just can't seem to pin-point why. 


Answer: I'd like to start off the week discussing the merits and issues associated with putting lids on terrariums.  

TL:DR Answer: lid your terrariums for 75-85% of the time.    

For those of you that have some more time: read on...

Nesting Ranch, I see that some of your terrariums are lidded and some were not.  Many terrarium vessels come with lids (candy jars, apothecary jars) but most do not.  I would encourage anyone with an open top terrarium to find a way to partially or fully cover the terrarium 75-85% the time.  The larger the ratio of vessel opening to vessel volume, the more necessary lidding the terrarium will be.  The lid helps maintain the humidity levels in the terrarium - which is necessary for most terrarium plants (mosses and ferns).  A fishbowl-type vessel is losing most of its humidity right through the opening in the vessel.  A wine bottle terrarium maintains humidity levels due to its small opening.

Ideas for lids: plexiglass, acrylic plastic sheets, small dishes or plates, tin foil, lids from other vessels.

With that said, you must uncover the terrarium for short periods of time - perhaps one day a week.  Outdoor ferns and mosses benefit from air circulation in addition to humidity.  You must allow this same air circulation for your terrarium plants occasionally.  This prevents plant rot and fungus growth as well.  

But every terrarium is its own ecosystem.  It takes some experience with "settled" terrariums to learn to watch the moisture accumulation on the glass as a gauge for how frequently to cover/uncover the lids.  If you see water droplets on more than 50% of the interior surface you should unlid for a day.  If the soil layer in the terrarium appears light and color and completely dry you need to consider lidding the terrarium more frequently.

Read more about lidding terrariums here.

How to Make a Moss Terrarium by Twig Terrariums

Garden Design Magazine shares a how-to guide for creating a moss terrarium ala the fabulous Twig Terrarium ladies.  The twelfth (and final step) contains a good comment in regards to long-term care for a terrarium: a well-made terrarium will become more self-sufficient over time and will need less care and watering.

Build Your Own Electronic Automatic Watering System

This short video demonstrates a DIY system for setting up automatic irrigation for a house plant.  I'm not convinced the soil-dryness sensor is sensitive enough to tailor for a finicky plant's water needs but this would probably work for a hardier, water loving plant.  The arrangement appears rather simple to set up if you have some electronics know-how.

Here's the full Instructable, via Lifehacker.

What Can Kids Learn from Making a Terrarium?

We've all seen the "make a terrarium with your kids" articles but Carmen at Off the Grid News makes a valuable point about the teachable moments you can share with your kids during the process:

As for science, a terrarium is a great way to learn about the water cycle. Water on the earth cycles through several different states from ground and surface water to clouds, to rain, and back again to the ground. It evaporates from the earth to become a vapor in the atmosphere. There, water condenses to form the water droplets that make up clouds. When they get large enough, the droplets fall back to the earth as precipitation, and the cycle begins again. In a terrarium, you get to see this process in miniature. You need only add water to it once a month because within the container, the water will evaporate, condense, and precipitate, just as it does in the earth at large.

Q and A: Plants for an Ornament Terrarium?

Q:  I am making a terrarium in an ornament. It will have a hole for air. Wondering what you think would be a ideal plant in that environment?

A: Some of the factors you will be considering for your project: finding a plant that will stay small, tolerate an open air hole, and won't need much soil.  See some very cute examples at lesliehalleck.com.

If you'd like to skip soil all together I'd suggest using a tillandsia (air plant) for your terrarium.  These are about the right size for an ornament.  They are easy to care for as you just have to submerge the
plant in water once a week in order to water it - and you could easily fill the ornament up with water, let it sit 15 minutes, and then pour it out.

If you did want to add soil to the ornament - I would suggest using cactus soil (or mixing regular potting soil with sand) and planting a small succulent in your terrarium. This way you won't have to attempt to keep a humid environment inside your terrarium and you can get away with watering it in very small, infrequent amounts.

Q and A: To Lid or Not to Lid (from the archive)

I am at a conference and will be sharing posts from the archive this week.

Question: I have a number of Moss terrariums, all are open top. I must go away for two weeks this december and was wondering what your advice would be on watering? Do I just seal them up and let them do their thing?

Answer: I am forever warning against condensation build up in terrariums. It can lead to rot and fungus growth and can be difficult to "dry out" a terrarium once the condensation appears. One way to avoid condensation is to maintain "open top terrariums" - which require more TLC (and more frequent misting) to keep hydrated.

But what to do over an extended holiday? Pack up your terrariums and take them with you! Haha. I'm joking. Lid them up. This is one circumstance where a little extra condensation will not do any grievous harm. If you have large "mouthed" open-top terrariums you may want to consider obtaining sheets of plexiglass or acrylic at your local hardware store and balancing them on the tops of your terrariums to form a lid. If the openings are smaller (ie. a bottle terrarium etc.) you can top with anything that fits- even cap the opening with a piece of foil.

If you are worried about the condensation you could try a test-run with a lid for 48 hours. If the condensation is overwhelming after the test you may want to try a lid with some holes punched in the top to promote airflow. A yogurt lid with some holes or anything similar would suffice. If it's a large "mouthed" terrarium that's getting too wet with a lid you can try balancing an acrylic sheet a little off-kilter to leave a small opening.

Upon your return home if you find your terrarium soaking wet you can remove the lid and dangle a strip of absorbent paper towel into the terrarium that touches the surface. This will act as a wick and after a few hours you would be surprised how much moisture it can absorb.

And enjoy your trip!

Q and A: Reviving sphagnum moss (from the archive)

I'll be heading out of town for a conference next week.  I'll be sharing posts from the Q&A archive so you might see something you haven't seen before!

Question: I was wondering if you could offer any more details on how to revive dried sphagnum moss? and how would I know if what I have is even capable of regeneration?

Answer: Most of the dried moss you find at craft stores is a form of dried long fiber sphagnum moss. These dried vine-like tendrils sometimes, but not always, contain the dormant live sphagnum moss. You can check for the live moss by looking for the "crowns" of the moss- which look like a small clover blossom. These crowns are a good indicator of a chance at sprouting the moss.

To propagate the moss you must provide a humid temperate environment with a decent amount of air circulation. This can be achieved in a bottle terrarium, a plastic take out containers with a few holes punched in the top or even large plastic bins with open tops. People all seem to have their own secret for success- a grow lamp or a partial submersion in standing water or even seaweed sprays.

Watch for the appearance of mildew, spidery webs or algae. If it's a small bit you can remove the offender but if it becomes expansive its best to start over with clean containers.

I have found that you can experiment with light levels and moisture levels- but you do need to stay patient. Sometimes it can take the live sphagnum moss a few months or more to revive. But once it becomes a bright green you know you are working with the live stuff.

Once it becomes a healthy darker green you can switch it over to growth on a soil substrate. Under the proper conditions and given enough time it can fill out to get the mossy miniature "grass" appearance.