The World’s Second Oldest Sealed Terrarium?


David Latimer’s terrarium hasn’t been watered in 47 years. Photo:

I am the proud owner of what I believe may be the world’s second-oldest sealed terrarium. 

The oldest one is claimed to be one grown by David Latimer of England, started in 1960, when he planted a single tradescantia cutting inside, and last opened in 1972, when he added a bit of water, then sealed again, never to be reopened. That means it has been growing inside its bottle with no additional air, water or fertilizer for 47 years. The same photo has been circulating on the Internet for at least a decade. David has certainly aged since then, but the appearance of the terrarium probably hasn’t changed.

My son Mathieu started “my” terrarium when he was 10 years old. He didn’t ask my permission nor my advice, but presented me one day with a large bottle with a miniature landscape inside, composed of cuttings he had taken from among my houseplants. He wanted to see how long plants could live in a bottle with no added air or water. So, we put it under my plant lights and waited. 

He is now 40 years old and his terrarium is still alive, making it 30 years old. That’s a far cry from 47 years, but still, I’ve not heard of any other terrarium older.

Gradual Evolution

Mathieu’s experimental terrarium 29 years later. Photo:

When he presented me with the finished terrarium, I knew the experiment wasn’t going to work perfectly. Most of the plants he had chosen weren’t “terrarium plants.” For example, he’d included some cactus in his mini-garden and they don’t like high humidity. And it was really very humid: condensation covered the sides of the bottle most of the time. Mathieu ought to have left it open for a week or so to bring the humidity down before sealing it forever. 

Over time, various plants petered out one by one, starting with the cactus: they only lasted a few weeks. And moss began to grow everywhere: on the soil, on the sides of the glass. Obviously, there had been moss spores either in the potting mix or the air when he assembled the terrarium. 

Sinningia pusilla is a tiny plant, but flowers wonderfully in a small terrarium: here, a wine glass. Photo: –ki—,

That appearance lasted for years, but even the moss has since died back. The sides are now covered in what I can only presume to be some kind of gelatinous translucent algae. And all the higher plants finally disappeared, except for one: a miniature sinningia (Sinningia pusilla). Instead of dying out, it spread. The original single plant is now a colony of—I’m guessing, of course!—over a hundred, entirely covering the soil. And they bloom on and off over the year, sometimes with dozens of flowers at once. But you can often barely see them through the glass, thanks to the algae and the condensation.

The 30-year-old terrarium is no beauty: for that, you’d need to open it up and give the sides of the bottle a thorough clean-up … but that would put an end to the experiment. So, there it sits under my plant lights, year in, year out, thriving in its own special way. 

How Does It Work? 

But how can plants survive for so many years inside a sealed container? It’s because they recycle everything! 

Plants photosynthesize during the day, using CO2 and giving off O2, then invert the cycle when they respire at night. Ill.:

They use carbon dioxide during the day for their growth and give off oxygen as a by-product. At night, they invert the process, giving off carbon dioxide and absorbing oxygen. They absorb water through their roots, then give it off through their leaves as water vapor that then condenses into water droplets again to water their roots. Minerals get recycled when old leaves and flowers die and decompose, fertilizing the news ones to come. (At any rate, most plants don’t need anywhere near the amount of fertilizer humans try to force upon them.)

The only “input” plants need is light, their unique source of energy, and I’ve been providing that by setting the container under my plant lights.

The Experiment Continues

The top of the terrarium used to be perfectly white; now there’s a bit of rust. Corrosion! It will eventually eat through the top and put an end to the experiment, but that could take another 30 years; perhaps even more. 

Mathieu, you’re hereby warned that when I die, you’re to recuperate the terrarium and either take care of it (all it needs is room temperatures and a bit of light) or give it to someone who will.

Thus, the experiment will continue and the world’s second-oldest terrarium will live on for probably a long, long time. 


Lawns Still Need Mowing in Fall


As nights get colder and colder, remember that lawn grasses continue to grow throughout much of the fall, usually only stopping when temperatures remain below 50˚F (10˚C) or so for a good week. Even a first light frost won’t usually not stop them. So, in many areas, you will still need to mow into November or even later, although less frequently than in summer.

However, when the grass finally does stop growing, it’s time to mow one last time … and shorter than you did all summer long, too, at about 2 inches (5 cm) in height. And for once, collect the grass clippings (you can put them in the compost or use them as mulch). This will help to better aerate the lawn grasses, making them more resistant to winter damage and especially to the diseases that often set up shop under the cover of snow.

Article originally published on October 5, 2015

Give Your Succulents a Weekly Walk!


A week in the sun and a week in the shade will keep your succulent happy!

Succulents are all the rage these days. Millenials, especially, as said to be wild about them, treating them practically like the pet dogs they’re not allowed to have in their apartment dwellings.

They’ve been told they’re low-care plants, that they need practically no water, even that they don’t need sun and will grow anywhere. But if the first part is mostly true, the last bit is an out-and-out lie. They do need light and plenty of it. In fact, although there are a few exceptions, they prefer full sun.

Salespeople can get away with lying about how to care for succulents because the latter react so slowly. If something is wrong, the plant won’t show symptoms for many months, even over a year. But that’s not because they thrive under low light, but because they die slowly. That beautiful echeveria you’re so proud of, with its blue to grayish to purple rosette of thick leaves, may well be starving from lack of light and simply showing no symptoms. By the time you realize it’s losing leaves and desperately stretching for more light, it may be too late to save it.

Switch ’Em Up

Here’s an easy tip on keeping succulents alive in the average apartment nearly forever. 

Place them in the ideal décor, the spot where they just look so cool—and probably far from any window—for only one week at a time. The second week, move it right up near your sunniest window, or at least as close as you can to the window without it touching the glass. Let it charge its batteries with solar energy for a week, then move it back into your décor. And repeat weekly.

Two weeks of intense light per month will keep almost any succulent happy; the other two weeks can be in nearly total darkness and it won’t matter.

Logically, of course, you’d buy two succulents so that, at any given time, one is doing décor duty and the other basking in sunlight.

So, like a pet, you need to take your succulent for a walk, but only once a week. 

Sometimes making plants happy is so simple!

Ill.:,, &, montage:

How to Overwinter Cannas


Winter is coming! Ill.: &, montage: laidbackgardener.coom

I hope your cannas did well this summer, providing great tropical-looking foliage and spectacular, colorful flowers. But as fall sets in, and certainly before winter hits, you have some choices to make. 

Cannas, you see, are essentially tropical plants and won’t overwinter outdoors in cool temperate climates. If you live in hardiness zones 9 to 12, that is, in a warm temperate to tropical zone, you can leave them in the ground. In fact, in zones 10 to 12, they may even continue growing and flowering through the winter as long as they receive sufficient rain. In zone 8 and in some parts of zone 7, you might want to risk leaving them outdoors if your soil doesn’t freeze more than superficially, especially if you mulch them (a good 6 to 8 inches/15 to 20 cm of chopped leaves or grass clippings would be perfect), as their “bulbs” (actually rhizomes) are underground and out of reach of light frost.

Elsewhere, you can either let your cannas freeze and replace them with fresh rhizomes next year, or bring them in. Here’s how to do the latter.

After Frost Hits

When frost hits, it’s time to get your cannas in. Photo:

Logically, you’d want to leave your cannas outdoors until frost hits, partly because they’ll keep growing and blooming until then. However, this also gives them longest possible growing season over which the plant can store food for next year’s growth. But when frost does kill them back (it will literally blacken the leaves!), their growing season is officially over and it’s time to act.

If there is no frost before mid-November (in the Northern Hemisphere; mid-May in the Southern Hemisphere) though, bring them in any way: you don’t want them to be still in the ground when it does freeze solid!

Container-Grown Cannas

The easiest cannas to handle are those growing in containers. Simply cut them back to 1 to 2 inches (3 to 5 cm) above the soil and bring them in. (More about where to store them later.) You can even pile pots one on top of the other. If you feel the need to repot them or divide them, you can do that in the spring.

In-Ground Cannas

Freshly dug, these rhizomes need a bit of drying and root trimming before storage. Photo: Rebecca Finneran, MSU Extension

Otherwise, before digging your cannas, cut the leaves and stems back to about 8 to 12 inches (20 to 30 cm) so they won’t be in your way. Now, dig up the root ball with a shovel or garden fork, using the leaf stubs as a handle to shake off the excess soil. Spread the rhizomes on newspaper, cardboard or an old blanket for about a week in a frost-free spot (a garage or shed, for example). Now, cut the foliage back completely (1 to 2 inches/3 to 5 cm from the rhizome) and trim back the thick roots. Clean the rhizomes roughly with a brush to remove most of the dirt. Don’t rinse them, though: they need to stay dry. 

Do make sure you label the rhizomes, with the cultivar name if possible; if not, at least as to flower color, leaf color and size (i.e. “tall red w purple leaves.”). Canna rhizomes all look pretty much alike when they’re naked and certainly, by spring you’ll have forgotten which is which! Either write on a plastic label with a twist tie and fix it to the rhizome or write on the rhizome with a garden marker. I find just placing plastic labels with the tubers risky: they always seem to end up being mislaid. 

Some people like to divide their cannas before they store them, but I only do this if the clump is really big and difficult to handle, in which case I simply break the clump in two or three. (It will separate along “natural lines.”) I do any precision dividing in the spring before starting a new growth cycle.


Plenty of canna rhizomes to store for the winter! Now, just cover them with a layer of wood shavings or peat moss. Photo:

If possible, store the rhizomes in a cardboard box or a plastic container (the latter should have a few holes so there’ll be a bit of air circulation), covering them with vermiculite, peat moss, wood shavings, or shredded paper. Or wrap them in newspaper. One friend simply tosses his into a series of plain trash bags (air circulation be damned!) and uses a twist tie both seal the bag and attach the label. Whatever works for you!

The ideal location for winter storage is a cool but not cold spot that remains between 40 and 55˚ F (5–12°C) for much of the winter. Spots to consider are root cellars, unfinished basements, crawlspaces and barely heated garages. 

You have nowhere cool to store the rhizomes? Don’t worry: they can be kept at room temperature if necessary, but if so, the rhizomes will tend to dry out over the winter, so check them monthly, giving them a spritz of water if they start to shrivel.

You need to check the rhizomes occasionally at any rate, even if you can keep them cool. Just remove any rotting rhizomes and lightly spray any shriveling ones.

You’ll see that the rhizomes may start to sprout well before spring, especially when conditions a bit warmer than they should be. Just ignore their pushiness and put them back into storage until you’re ready. After all, who’’s the boss here, you or the rhizomes?

Come Spring

Dividing rhizomes. Photo:

By earliest spring, the rhizomes will be itching to grow and starting to sprout. This is the time to divide them, if necessary. Rhizomes stored in their pots can be dumped out for division at this point. Most will be too pot-bound to leave in the same container more than a year or two.

In areas where spring comes early, you can plant canna rhizomes directly in the garden as soon as there is no more risk of frost and the soil temperatures rise above 55˚ F (12° C). Don’t plant them while the soil is still cold: that will just stunt their growth. 

Plant them in full sun in rich soil (add slow-release fertilizer), covering the rhizomes with about 3 to 4 inches (8 to 10 cm) of soil and setting about 12 to 18 inches (30 to 45 cm) apart, depending on the size of the plants. 

Giving cannas a head start indoors. Photo:

In colder climes, cannas will need a head start indoors if you want to see them bloom before summer’s end, so, about 4 to 5 weeks before the expected last frost, pot them up temporarily in pots about 12” (30 cm) in diameter, barely covering them in soil (you can plant them deeper when you move them to the garden). If they’ll be growing in a pot all summer, you might find it practical to plant them directly into their final container, probably a large tub. 

Place the pots in front of a sunny window indoors, in a cold frame or an unheated greenhouse: somewhere there is plenty of light. Start watering lightly, increasing as sprouts appear and start to grow. Then plant your cannas out once the soil warms up (again, 55˚ F/12° C is the minimum) and there is no danger of frost. 

💡Helpful hint: If you’ll be placing pot of cannas in a water garden (cannas can be grown as semi-aquatic plants), cover the container’s soil in about 2 inches (5 cm) of gravel. That will help keep the soil from floating away and dirtying the water.

And there you go: successful overwintering for cannas!

Don’t Clean Up Your Garden in the Fall


Ill.: Claire Tourigny

If you feel the need to clean up a flower bed or vegetable garden (and many gardeners insist on doing so, even when they know may know it’s harmful: they just can’t seem to help themselves!), it’s certainly not something you want to do in the fall. The more a garden is littered with plant residues over the winter, the better the condition it will be in the spring. And there are many reasons for that, including:

• dead leaves and stems protect permanent plants (perennials, bulbs, shrubs, etc.) against the cold;

• garden waste left in place (dead annuals, leaves, etc.) protects your precious garden soil from erosion;

• yanking out dead vegetables and annuals disturbs the soil’s natural balance and is harmful not only to beneficial soil microorganisms, but even to larger ones, like earthworms, 

• the very best nutrient source for any plant is its own decomposing leaves;

• beneficial insects overwinter in “plant waste” and, if you leave it in place, the “enemies of your enemies” will be there the following season to help deal with plant pests;

• the seed capsules of the plants you didn’t cut back will attract birds and feed wildlife;

• and the list goes on and on.

Cleaning up a garden in the fall is simply an unnatural practice!

Even knowing that, though, I know many gardeners will hesitate. “Imagine all those soggy leaves we’ll have to pick up in the spring if we don’t do it in the autumn!” is a common thought.

But that’s the beauty of the whole thing! When spring comes, most “waste” magically disappears. The leaves largely decompose over the winter and the first warm days of spring complete the process. And you can leave what little is left on the ground as a mulch. There is, in fact, very little to pick up in the spring, just a few dead stems still standing, not even a fifth the of stuff you would have bagged in the fall.

In a nutshell, the less you clean up in the fall, the more beautiful and healthy your garden will be. Who knew?

Just trust Mother Nature: she always knows what to do!

How Oaks and Beeches Control Their Predators


During a mast year, squirrels find more acorns than they can eat. Ill.:, montage:

Squirrels, jays and other nut-eating animals like nothing better than fattening up on acorns, chestnuts and beechnuts in preparation for winter. They’re rich in oils, protein and carbohydrates, as well as calcium, phosphorus, potassium and the vitamin niacin. Not only do nut-munchers stuff themselves on the nuts, they bury countless others for future eating… then either forget to dig them back up or finally don’t use them, as they typically hide far more than they’d need when the harvest is good. Thus, they actually plant future beech, chestnut and oak forests, bending to the will of the trees.

Population Control

And oaks, chestnuts and beeches are even craftier than you might think. If they produced equal numbers of nuts every year, the squirrel and jay population would remain high and they’d consume most of the fallen nuts. Instead, they have “mast* years”: years in which they produce huge quantities of nuts, far more than their predators could possibly eat, followed by several to many years of slim pickings. This keeps the squirrel and jay population relatively low. 

*Mast: name for the fruit of beeches, oaks, chestnuts and other woodland trees.

How? When a mast year occurs and thus food is plentiful, there aren’t that many nut predators around, as they’ve gone through several low-nut winters in a row. The winter and summer following a mast year, since food is plentiful, many more predators survive the winter and the forests fill with squirrels and jays. But the following winter, after a skimpy harvest when there’s little to eat, fewer squirrels and jays survive. And several years in a row of low nut production really keep the population in check. Mast years occur every 3 to 15 years, depending on factors yet unknown.

And the off years, when few nuts are produced, allow the nut trees to store up more energy for the next mass year.

Coordination Is the Key

Of course, this wouldn’t work if each oak, chestnut and beech in the forest were on its own schedule and thus there were always trees having a mast year each fall. Instead, the trees somehow collaborate locally. All the nut trees in a given region will have their mast year all at once, followed by several coordinated years of low production. 

It’s possible trees communicate with each other to coordinate a mast year. Ill.:

How do the trees coordinate their mast years? That remains a mystery. Perhaps there is a climatic signal of some kind that indicates that a certain year would be a good one to hold a mast year. Others theorize that the trees actually communicate with each other, not in words, but by sending signals from tree to tree via their roots. (“Hey, guys! We’ve been taking it easy for the last six seasons, storing up our energy. Why don’t we make this year a mast year!”)

Whatever the reason, mast years have been recognized by foresters (and nut harvesters) for generations, but it’s only recently that the reason behind them – over- then under-producing to control predators – has been studied. 

Ain’t nature wonderful!

Underpot to Keep Indoor Trees Under Control


Do you really want your indoor trees to reach the ceiling? Photo:

Indoor trees are marvelous things. They give you the feeling of being in the great outdoors even while you’re in your own living room. They provide shade, making reading easier, they help purify the air and they perk up your décor like nothing else. But they do tend to get big over time. Ficus, scheffleras, money trees, corn plants and other indoor trees just want to keep growing. In nature, some can reach 50 feet (15 m) or more in height. That’s just not possible indoors. So, what’s an indoor gardener to do?

Benign Neglect

Once your indoor tree (here, a Ficus benjamina) has reached the size you want, slow it down by no longer potting it into bigger containers. Photo: Julie Deken,

One thing you can try that requires very little effort on your part is to simply stop potting them up. That is, start leaving them in the same pot year after year instead of moving them to a bigger one every two to three years, as you’ve been told you ought to do. With their roots severely constrained, most trees wisely start to grow more slowly, some putting on almost no new growth worth mentioning, but simply replacing older leaves with fresh ones. 

Severe underpotting has helped keep this nearly 400-year old bonsai small. Photo: Ragesoss, Wikimedia Commons

Underpotting in this manner has been used in producing bonsais, tiny, pot-bound replicas of full-sized trees, for 2,000 years. On indoor trees, you simply apply it at a later stage, when they’ve reached the size you want.

Now, depending on the species, some selective pruning may also be needed, cutting back taller branches to stimulate denser, shorter growth, but by the time a tree has been in the same pot about three years, you’ll find you won’t need much of it. Underpotting will have slowed it down considerably.

Saves Time, Effort and Cash!

Repoting a large plant is a lot of work. Do you really want to do it? Photo:

Besides, repotting a big plant is a major hassle. They’re heavy and awkward to manipulate. Just getting the old pot off without a second pair of helping hands can be a struggle! If you keep the plant in the same pot year after year, you avoid that.

Plus, you save the price of fresh soil and the cost of a new, bigger pot. OK, admittedly, potting soil is not that expensive, but pots—certainly big pots suitable for an indoor tree—certainly can be.

What About Mineral Salt Buildup?

Mineral salt buildup inside a pot. Photo:

One of the reasons for repotting houseplants has always been to reduce the buildup of mineral salts, deposits caused by the use of hard water and fertilizer that have high concentrations of dissolved substances such as calcium carbonate, sodium, and iron. They’re often visible as a sort of white to yellow crust forming on the inside of the pots and are a sign the potting mix is becoming slowly toxic to the plant. By repotting into a larger pot, thus changing part of the old growing mix and adding fresh, uncontaminated mix around the root ball, you can help alleviate that. 

So, what happens if you’ve stopped moving your tree into bigger and bigger pots. Won’t the mineral salts build up until they kill them?

Not if you try one (or both) of two things: leaching and top dressing. 

In leaching, you pour fresh water over the soil until it drains out the bottom. And keep it up until you’ve applied the equivalent of two to three times the pot’s volume. That will dissolve and carry away much of the minerals. Then you simply throw away the drainage water. 

It’s easy enough to leach a small houseplant in the kitchen sink, but trees may need to be leached outdoors. Ill.: Claire Tourigny, from the book Les 1500 trucs du jardinier paresseux

Leaching a tree while it’s indoors is pretty much impossible, though. It’s not as if you can put it in a kitchen sink to leach it as you would for a smaller plant. And it may no longer fit into the shower. I leach my indoor trees simply by putting them outdoors for the summer without a saucer underneath. There, Mother Nature does the leaching by supplying regular downpours. In a drier climate, simply water more than strictly necessary and the leachate will drain off, carrying the excess minerals away. 

Top dress by scraping off the top layer of potting soil and replacing it with fresh mix. Ill.: Claire Tourigny, from the book Les 1500 trucs du jardinier paresseux

To top dress, just scrape off the top layer of soil (about an inch/3 cm or so) annually and drop it into the compost pile. That works because mineral salts tend to migrate upwards and mainly accumulate in the top part of growing mix. By removing the top layer of soil, you’ll severely reduce mineral salt buildup … and all that’s left to do is to replace the inch (3 cm) of soil removed with an equal amount of fresh potting mix.

How Long Can You Delay Repotting?

But how long can you keep this underpotting thing going? 

Actually, I don’t know the upper limit, but I have some fairly imposing corn plants and ficuses that haven’t been repotted in 20 years and they’re still doing fine just through leaching them outdoors in the summer and annual top dressing. And remember 400-year old bonsais in their tiny, root-cramped pots. 

I therefore figure there is probably no real upper limit. You can just keep not potting up pretty much forever.

So, slow your trees down by not repotting them, a laidback solution to a common houseplant problem!