Collectors Corner Fact Sheet
Terrariums
A terrarium is an enclosed or partly enclosed container designed to grow plants, they can be dry desert environments to tropical moist containers for rainforest plants.
Terrariums were once used by earlier botanists to keep alive and transport plants during lengthy sea voyages.
A terrarium can be a simple containers with one plant in it or a complex landscape with many plant types.
A plant can be sealed in a glass jar with the correct level of moisture and exist for many years without being opened.
Closed terrariums, these generally require far less work than open terrariums as their environment becomes self contained, provided that light and moisture levels are correct levels the terrarium will self maintains itself.
Many plants however will not thrive under closed conditions as they will rot and if rotting occurs it can damage other plants.
Open Terrariums, these are similar to growing plants in pots except that the environment is partly closed creating a more stable environment for plants to grow. A much larger range of plants can survive in open or ventilated terrariums as many plants do not like the high humidity offered in closed terrariums.
Position
Terrariums must be positioned where they receive enough light for the types of plants being used.
Succulent plantings will require strong sunlight whereas Peperomia and similar plants can survive with normal house lighting.
Modern LED lights now allow cheap internal lighting with no heat being generated making them ideal to light terrariums.
Many indoors plants commonly used in terrariums are tropical plants, as indoor temperatures drop in winter move the planter to a warmer area where day temps get at least 18 degrees, colder nights will be okay if day temps increase above 20 degrees.
In extreme cold many of the plants may perish.
Watering
The secret of any terrarium care is watering.
A closed terrarium must be only barely moist otherwise the glass will constantly be covered in heavy condensation and plants will often rot.
When overwatered these must be kept open until the right moisture level is achieved. Often the only water needed will be a few table spoons.
Open terrariums require watering weekly to monthly depending on location and types of plants.
Water should wet the soil but not allow the bottom of the planter to have sitting water after a couple of hours.
Measure the water used and use this amount each time.
An example is if the terrarium has 2 liters of potting mix it may need 300ml of water each time.
Do not water a terrarium until the top of the mix feels almost dry.
A good potting mix will be one where the water will rapidly move throughout the medium and rewet any dry areas.
This way the terrarium need only be watered in one spot and the foliage can be kept dry.
Fertilizing Closed terrariums do not require fertilizing unless the potting media used is devoid of any fertilisers, most potting mixed will deliver food as they slowly decompose.
In a terrarium we are trying to keep plants small and compact so avoid fertilizing unless necessary.
Potting media
There are many views published by different authors on this subject.
You can design terrariums with layers for drainage, chemical absorption etc., all this can work but we do not believe any of the methods are essential.
Our recommendation is any good open potting mix which includes any of the following, pine bark, a commercial mix should be clean of pests so should not need sterilization., vermiculite, pearlite, peat moss.
For ease of watering mixes made from Pine bark are the easiest to maintain.
Drainage is not essential and in some instances will prevent the water from reaching the potting mix.
Charcoal is worth using if available but not essential.
Depth of mix in planters will determine frequency of watering and speed of plant growth.
No mater what media is used it is essential that correct watering practices are maintained otherwise the best systems will fail.
Maintenance
Terrariums are designed for low maintenance but a fact of life is all plants want to grow so plants will need to be cut back occasionally to reduce size.
Dead foliage should be removed as it can encourage moulds.
Pests & Diseases
It is essential that plants and media are inspected for any pests before they are used.
They will grow or breed rapidly in a terrarium.
Fungi and other infections are often present on the plants introduced so if the environment is ideal for the fungus it will grow.
Mold and mushroom like fungi can grow in bark based mixes unless watering is managed correctly.
