It's been a long time since I've made a terrarium, but hanging around in the woods this past week while loading cut firewood brought me into contact with so many perfect woodland specimens that I wanted to bring them all home and preserve them under glass. Mosses, lichen-covered branches, weird fungus on rotting logs, rocks capped with moss, miniature ferns, partridge berry, princess pine — even tiny spruce and maple seedlings — were everywhere I set my feet, it seemed, so I decided I'd bring a collecting container, knife and small trowel with me next trip. But first, I needed to get materials together so I could put my delicate plants into a moist environment immediately.

The artificial environment of a terrarium is a direct descendant of the cases invented by Dr. Nathaniel Ward in the mid-1800s. An amateur botanist who loved to grow ferns in his London yard, Ward found the air was so polluted by nearby coal plants that none of his plants survived. To provide a healthy and humid environment for the ferns, Ward developed miniature glass terrariums, based on the same principles used in the huge glasshouses built in Kew Royal Botanic Gardens, just outside London, to house all sorts of tropical plants from the far reaches of the British Empire as explorers and scientists collected and identified thousands of species of plants. Ward's cases, originally used for elaborate displays of houseplants in Victorian parlors, were soon used to transport live plants back to England without killing them, protecting orchids and other delicate specimens from salt spray and temperature changes.

You can still buy ornate Wardian cases to fill with plants, but almost any glass container can be used for a terrarium: large gallon glass jars that formerly held condiments, clear Christmas ornaments, fish bowls, candy or apothecary jars, kitchen canisters, or recycled aquariums. Glass cloches or food covers can be used as covers on all kinds of shallow dish bases. For a terrarium on a pedestal, use a cake stand topped with a glass cloche.

The wider the mouth of your terrarium, the easier it will be to fill it. There are special terrarium tweezers, but you can always use tongs or chopsticks for placing plants in tight places.

All you need, once you've selected a container, is pebbles, horticultural charcoal (available at nurseries and greenhouses) and potting soil. Spread a 12- to 1-inch layer of pebbles in the base of your container for a drainage system. Top with a 12-inch layer of the charcoal, which will keep your soil sweet, absorb impurities and improve drainage. Arrange your plants and decorative rocks or twigs, or whatever you've selected for inclusion, on top of the soil in the container, leaving enough space between them and the glass sides for plants to grow. Then carefully dig out a space in the potting soil for each plant, place them in the holes and firm the soil around the plants’ roots. Then cover the soil with your moss, spritz with water, and place the lid on the jar. Place your terrarium in a well-lit spot but out of direct sunlight, because the glass will intensify the sun's rays. Terrariums are so humid they shouldn't need additional misting. They also shouldn't need fertilizing, as the idea is to keep the plants small.



Not everyone has access to private woodlands, so if you should want to collect natural plants, ask permission from private landowners and always take only a portion of whatever plants you harvest. Think of combining foraged specimens with small houseplants: creeping fig, dwarf coleus, delicate ferns, nerve plant, peperomia - any plant that likes low light and humidity is a candidate. And consider your tiny landscape as a place of change, like the garden and woods outside. I noticed that even on the tiniest maple seedlings the leaves were turning and wondered if, once inside, they would drop as if autumn continued under glass. If so, a spruce seedling would be a better choice than giving display space to a bare twig. Real mushrooms are very pretty in a woodland terrarium but will soon need to be replaced. In the very first terrarium we ever made we included a tiny morel mushroom. The next day, it had grown alarmingly out of scale in our miniature landscape, and on the morning of its third day in captivity we awoke to find the morel pushing up the lid of its apothecary jar, a fungal Frankenstein. Children like to people their terrariums with small animal figurines, make tiny paths or install tiny twig fairy houses. At Christmas, tiny ornaments can be added to terrariums to make them the perfect gift for friends with black thumbs.

While they are low-maintenance, terrariums do need a bit of care. If plants get leggy, prune them back. If a plant looks unhealthy, take it out immediately as it can infect other plants. Just dig the plant out with a mini trowel or long spoon, being careful not to disturb the roots of other plants, and replace it with one of similar size and light requirement. If you see water beading up on the glass, leave the top off your terrarium until it has dried out.