Autumn terrarium with pumpkins: open, closed and a little Halloween
Autumn is the season where a terrarium (or bottle garden) suddenly makes a lot of sense. It gets dark early, the heating goes on, and most houseplants start sulking. A terrarium keeps going. And with a few mini pumpkins, some moss and a warm light behind the glass, you get a bit of autumn indoors without buying a whole bunch of new deco.
In this post we go through open and closed autumn terrariums, real versus fake pumpkins, why succulents are the easiest autumn choice, and how to turn the whole thing into a Halloween terrarium for a few weeks.
Open or closed for autumn?
The difference matters more in autumn than in any other season, because the air in your house changes.
Closed terrarium
A closed bottle garden with a cork lid makes its own water cycle. Water evaporates, condenses on the glass, runs back into the soil. In autumn and winter that is a real advantage: your radiator dries out the air in the room, but inside the glass the humidity stays high. Ferns, fittonia and moss keep their colour while the rest of your plants go dull.
What a closed terrarium does not like: anything organic that rots. That is the whole issue with real pumpkins, more on that below.
Open terrarium
An open terrarium is the opposite. Air moves through it, moisture escapes, the soil dries out between waterings. That makes it the right home for succulents and cacti, and it also means you can put loose autumn deco inside and swap it whenever you feel like it. Pumpkin in October, pine cones and a small deer in November, done.
If you want one terrarium that carries you through the whole autumn and winter, an open one with succulents is the practical answer. If you want green that stays lush without you doing anything, go closed.
Pumpkins in a terrarium: real or fake?
Both work, but not in the same place.
Real mini pumpkins
Real mini pumpkins look great. The colour, the ribs, the little stem, nothing artificial comes close. Use them in an open terrarium only. Sit them on top of the moss or gravel rather than pressing them into wet substrate, and give them a dry spot so the underside can breathe.
Expect roughly four to eight weeks out of a small ornamental pumpkin indoors. Check the base every week. As soon as you see a soft patch or the first white fuzz, take it out. In a closed terrarium a real pumpkin will mould within days, and that mould will not stay politely on the pumpkin. Do not do it.
Our mini pumpkin set of 3 is sized 6 to 8 cm, which fits inside most terrarium jars without crowding the plants out.
Fake pumpkins
Artificial mini pumpkins are the answer if you want a closed terrarium with an autumn look, or if you simply do not want to check on anything. They do not rot, they do not sweat, and you can pack them away in a box and use the same ones next year.
One thing to watch: cheap foam pumpkins in a closed jar can get a film of condensation on them and look grubby. Ceramic, resin or a well finished polyfoam pumpkin holds up better behind glass.
Ready-made autumn kits
If you would rather not source pieces separately, we build two autumn kits with the plants and mini pumpkins already matched:
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Little Joe Autumn, Ø 20 cm and 22 cm high, a good first kit
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Emma Autumn, Ø 23 cm and 25 cm high, more room to build up layers and a landscape
Both come as a DIY kit, so you plant it yourself. That takes about half an hour and is the best part.
Succulents: the low effort autumn terrarium
Succulents get overlooked in autumn because everyone reaches for moss and ferns. But they suit the season well for a boring, practical reason: your house is dry and dark, and succulents mind that less than tropical plants do.
A few things to know for autumn and winter:
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Water much less. From October onwards, once every three to four weeks is usually plenty. Succulents in a glass container rot from too much water, never from too little.
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Give them your brightest window. South or west facing. If they stretch out and go pale, they want more light.
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Never a closed lid. Succulents in a sealed jar will rot. Open terrarium, always.
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Keep them off the radiator. Direct heat from below dries the substrate unevenly.
Kits we make for this, all open terrariums:
Already have a terrarium standing around? The succulent refill and starter kit gives you three succulents plus substrate, which is the cheapest way to bring an empty jar back to life for autumn.
Autumn deco that actually fits inside glass
The trap with seasonal deco is scale. Most autumn deco is made for a table, not for a 20 cm jar. Anything you put in a terrarium has to be small enough that the plants still read as plants.
What works:
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Moss. The single best autumn upgrade. A layer of green or dark green reindeer moss turns bare substrate into a forest floor.
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Small pine cones. Look for 4 to 6 cm. Anything bigger dominates the whole scene.
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Bark and a few dried leaves. Fine in an open terrarium. In a closed one, be careful, dried organic material plus permanent humidity equals mould.
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Miniature figures. A deer, a mushroom, a hedgehog. Our Forest Friends set is 1 to 3 cm, which is the right size for a terrarium rather than a dolls house.
Keep it to two or three elements. A terrarium with eight things in it stops looking like a landscape.
Turning it into a Halloween terrarium
Halloween is a nice one for terrariums, because the mood you want is already there. Damp moss, dark green, glass, a bit of gloom. You are only adding the last five percent.
Three things that do the work:
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Go darker on the plants. Dark moss, a fittonia with red veins, black gravel instead of white. The deco reads much better against a dark base.
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Add one or two figures, not ten. A single small skeleton peeking out of the moss beats a crowd. The Horror House mini figures are 1 to 3 cm, so you can hide one behind a plant and let people find it.
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Use light. This is the one that makes people stop and look. A terrarium lit from behind at night throws the plant shapes onto the wall. Glow in the dark figures like the Spooky Squad set charge up during the day and quietly glow once you turn the lights off.
The good part: it is all reversible. Pull the figures out on the first of November, leave the moss and the pumpkins, and you have an autumn terrarium again. Swap the pumpkins for pine cones in December and it carries on.
Everything for this, plants, kits, pumpkins and figures, sits together in our autumn and Halloween collection.
Autumn care in three lines
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Light. Days get short, so move your terrarium closer to the window, but not into cold draught or direct midday sun through glass.
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Water. Closed terrarium: almost never, only if the glass stops fogging up entirely. Open terrarium with succulents: every three to four weeks.
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Heating. Keep it off the radiator and away from the hot air of a wood stove. Sudden heat is the main reason terrariums struggle in winter.
Where to start
If you want green that looks after itself, go closed with fake pumpkins. If you want to change the deco with the season and keep it simple, go open with succulents. Either way, start with one jar, plant it yourself, and see how the autumn light hits it in the evening. That usually settles it.
Have a look at the full autumn and Halloween range to see what suits your space.
