Terrarium Care Tips Series: All About Water
When it comes to watering, each terrarium will differ slightly depending on several factors. Jar size, amount of soil, environment (does your home have very dry air?), lighting, etc. All of these factor into a watering schedule. Terrariums with tightly fitting lids will lock moisture in more easily than those with any type of gap or those without any lid at all, resulting in a longer period of time between waterings. These terrariums can be lightly sprayed once every 6-8+ weeks. However, if you own a terrarium that is not tightly sealed you will want to water more frequently (these can be sprayed every few weeks). Adding an occasional 1/2-1 cup of water to the soil will help raise humidity inside the jar.
Also essential to the health of your terrarium is the use of the correct type of water. But isn't all water the same? Not when it comes to watering moss. Moss is a hardy plant; it can withstand freezing temperatures, minimal to no light (for a limited amount of time), and complete drought. But when it comes to the chlorine, chemicals, and heavy metals present in tap water moss will quickly suffer. In fact, using tap water even once or twice can cause moss to begin to yellow and eventually die. To make matters worse there is nowhere for these substances to go in an enclosed glass case so they accumulate very quickly.
So what kind of water should be used? Natural spring water, rain water, or distilled water is best. Some popular and easy to find brands are Aquafina and Ice Mountain, and at around $1.00 - $2.00 per bottle (which will give you at least 6-12 months worth of watering) it's not going to break the bank.