Terrariums Are Making a Comeback; Projects Can Be Fun, Educational

Question: My daughter would like to build a terrarium. It’s been years since I had one. How do I go about starting one?

V.J., Garden Grove

Answer: Terrariums are fun and educational projects for children. They were, of course, popular in the 1960s and early 1970s, and have been experiencing a comeback in recent years.

Be aware, though, that terrariums aren’t the low-maintenance miniature gardens they were once touted to be. They do need regular care.

To have success with a terrarium, you need to choose plants that will grow well together, not overwater them and provide adequate light. If grown right, a terrarium can last for years.

When assembling and caring for your terrarium, keep the following tips in mind:

* Choose a container. Your options are virtually limitless: Aquariums, fish bowls, large jars and milk jugs. Keep in mind that the larger the container’s opening, the easier to install and care for the plants. An aquarium is a good choice for beginners.

* Select your plants. Choose plants with similar growing requirements. Foliage plants are usually the easiest, although some flowering varieties will survive in terrariums in ideal conditions.

Avoid plants with fuzzy leaves, because their foliage holds too much water and they’re subject to rotting.

Inspect plants carefully for pests. Starting with pest-free plants will help prevent having to deal with insects or disease later on.

For the best visual effect, choose plants of various sizes and heights and include some with variegated foliage.

To avoid frequent replanting, choose slow-growing plants. And for the same reason, don’t crowd plants into the terrarium; leave some room for growth. Also, an odd number of plants usually looks best.

* Set up. Besides plants, you’ll also need gravel, charcoal, planting mix and accessories such as ceramic figures or rocks.

Put a 1-inch layer of pre-moistened horticultural gravel on the bottom of a completely dry aquarium or other container. Then add a 1/2-inch layer of slightly moistened charcoal to absorb foul odors. On top of the charcoal, put 2 to 3 inches of a pre-moistened potting soil containing perlite for good drainage.

* Plant. If you have a wide-mouthed container, this is easy. Make holes for the plants; put them in the holes and firmly press the soil around the base.

With a small opening, however, this process gets tricky. You might have to use a stick or wooden spoon to make holes for the plants. Then carefully lower the plants into the holes with tongs and press the soil down around the roots with the handle end of the spoon.

* Create a scene. Building a terrarium is like making a tiny garden. Add visual interest by mounding the soil in some areas to form little hills. Include various accessories such as rocks, polished stones, colored pebbles, marbles, small mirrors and ornaments as tiny gazing balls. Some people furnish the terrarium with doll furniture, such as tables, chairs and umbrellas.

* Top it off. When planting is complete, lightly mist the terrarium. Clean the sides with a cloth. Keep the top open until the mini-garden has dried and there is no condensation on the glass. Then cover the top with glass or plastic.

After a day or two, check the terrarium for condensation, because overly moist conditions will lead to rot. To minimize wetness, ventilate the terrarium by removing a corner of the covering at all times and by avoiding temperature fluctuations.

* Provide appropriate light. Terrariums need bright light or to be covered by a couple of 2-foot fluorescent light tubes 14 hours a day.

* Water sparingly. Terrariums need very little water. Water only when the top of the soil appears dry.

* Feed sparingly, too. Fertilizer causes plants to grow, which you don’t want to encourage. After four months, use a small amount of liquid plant food at 1/8th strength. Repeat every four to five months.

Have a problem in your yard? University of California Cooperative Extension (UCCE) Master Gardeners are here to help. These trained and certified horticultural volunteers are dedicated to extending research-based, scientifically accurate information to the public about home horticulture and pest management. They are involved with a variety of outreach programs, including the UCCE Master Garden hotline, which provides answers to specific questions. You can reach the hotline at (714) 708-1646 or send e-mail to ucmastergardeners @yahoo.com. Calls and e-mail are picked up daily and are generally returned within two to three days.