A terrarium is an indoor micro-garden that can provide years of pleasure. Terrariums are not carefree but will thrive on a minimum of attention.
Light and Temperature:
Keep your terrarium in indirect light. Direct sunlight will overheat the container and injure your plants. Flowering plants such as African Violets, Sinningias, Begonias, Epicsais, and Orchids need additional light to bloom. Place terrariums containing blooming plants in an east window and remove the cover when exposed to direct sunlight. Plants become “leggy” when there is insufficient light. Stems and leaves tend to be weak and are more susceptible to fungus attack than more sturdy plant growth.
Terrariums can be placed anywhere in the home if artificial lighting is provided. Blooming plants particularly respond to their own direct light source with more flowers and improved leaf growth. Use either fluorescent or incandescent bulbs to light a terrarium. The former are preferred for their cooler temperature and more even distribution of light. Many special bulbs are on the market, such at Vita-Lite, which emits long and medium ultra violet rays, in addition to a wide spectrum of other needed wave lengths, and inhibits stretching of plant stems.
Houseplants in containers without drainage holes pose a special problem for the indoor gardener. Water remaining in the bottom of the container can rot the roots and damage plants. Feel the soil, look at the plants, water cautiously and only when dry. You do not need to fertilize for at least a year, then only fertilize at half strength every six months.
A terrarium with no cover will naturally need more water, though water sparingly—do not over water, and should be misted daily. A covered terrarium recycles water by producing condensation during periods of active photosynthesis or increased heat in the room and the water then drips back into the soil. Periodic checking of soil moisture is still essential.
Since most containers have no drainage, and to keep the growing medium in good health, it’s best to…
Add a layer of fine gravel for drainage – topped with a layer of fire charcoal chips – if no gravel is used, then a half-inch of charcoal should be used. Then add an inch or more, depending on the depth of the planting area, of potting medium.
If planting a desert-scape, using only cacti and other succulents, add extra sand, grit or perlite to the potting medium. And a terrarium without a cover is best for a desert-scape. Water seldom and just enough to wet the top 1/2 inch to 1 inch of soil.