A Wardian Case is another name for a terrarium. The case was invented by Dr. Nathaniel Ward, an explorer and plant collector in the 19th century, to protect plants from salt spray on ships while he traveled. While Dr. Ward's case was probably a very ornate terrarium, today a terrarium can be anything from a fish tank or a plastic bottle to an open-air container made from a dish. Because a terrarium is a miniature environment, you can use compost made of manure to improve the quality of the soil.
Layer pea gravel into your terrarium to a depth of 3 inches. Since there is no drainage in the terrarium, the pea gravel will keep excess water away from the roots of your plants.
Place a ½ inch layer of activated charcoal over the pea gravel. The charcoal will absorb any odors in your terrarium. You can purchase activated charcoal at an aquarium supply store.
Spread a 1-inch layer of peat moss on top of the activated charcoal. This will prevent the soil from falling into the pea gravel.
Add your compost to the terrarium over the potting soil to a depth of 4 to 6 inches. The compost is very nutrient-rich and can promote heavy growth in your terrarium plants. For a less nutrient-rich compost that will not promote vigorous growth, you can mix the compost with potting soil.
Plant your plants into the soil and water sparingly with a watering can. Since your terrarium is a closed environment, you will need very little water.