Closed Bottle Terrariums
The moisture inside a closed terrarium is constantly recycled, so they need minimal care. A layer of condensation on the inside of the glass container is normal and part of the water cycle within the terrarium.
Your terrarium will rarely need watering, if at all however if you notice the soil turning a light brown, add a few drops to dampen it. If the terrarium is placed in an ideal position, the soil should remain damp without the need of additional water.
Please ensure your closed terrarium is placed away from direct sunlight (windowsill) as the Fittonia will wilt or require additional water.
The environment is one of the most important factors to consider before watering your air plant. If the plant is placed in a moist or humid room, they will need less watering as the plant takes its moisture from the air. However in drier rooms - perhaps those with heating - the plants will need more water and misting.
Your air plant must be completely dry before misting as if they are over watered, the plant will develop root rot. They can also suffer from dry rot if the plant doesn't receive adequate air flow and will appear brown at the tips.
In Spring and Summer months, I soak my air plants in a bowl of water for 15 minutes. Next, I gently shake them before placing the plants onto a towel. Once the plants are completely dry, I return them to the terrarium glass.
During the colder months, I mist my air plants once a week but if the heating is on more frequently in my house, I will increase the misting to 2 times a week.
Succulents, Aloes and Cacti
As there is little drainage in open terrariums, the plants require minimal watering. It's best to water as close to the roots as possible to ensure the water is evenly distributed.
Succulents and Aloes:
In the warmer months, I water my succulents and aloes once every 2-3 weeks. Use no more than a few drops of water per plant. During winter, I lightly mist (spray) once a month and avoid watering the roots directly.
Terrariums with succulents and aloes need bright but indirect sunlight. It's best to place your terrariums in a bright room near a window.
Cacti need most of their watering during their growth period which is usually from March to September. I recommend watering each plant with a few drops every 2 weeks. However, the soil must be completely dry - if it is still even slightly damp, wait another week or so.
Most cacti go dormant from Autumn until Spring which means they stop growing. I only lightly spray in Autumn and avoid watering altogether during Winter.
Cacti need bright and direct sunlight so place your terrarium as close to a window as possible.
Moss balls require medium indirect sunlight, if placed in direct sunlight they will develop brown patches.
They can also adapt to low light conditions.
I replace the water for my moss balls every 1-2 weeks. Simply empty the contents of the moss ball terrarium, run the moss ball under cold water and gently roll it between your hands (the same motion as making a sphere), place it back into the glass vessel and fill with regular tap water.
The moss ball may float for a couple of days and bubble as it absorbs water but it will soon sink again.