Despite their preference for shaded situations outdoors, ferns will not do well in low light areas inside. Ferns need plenty of indirect, fairly bright light. They should not be placed close to windows that receive hot afternoon sun and, even exposure to direct morning sun, may cause some burning in summer, although a light curtain may be enough to moderate the exposure. Rotate the pot every week or two to encourage more even growth.
A bathroom with good natural light is a great place for ferns as they revel in humidity. They don't like to be splashed with hot water though!
Lack of humidity and dehydration is often responsible for the failure of ferns indoors. Air conditioning in summer and heating in winter both produce an extremely dry atmosphere. To maintain humidity:
*group plants together
*sit pots on a layer of pebbles in a saucer
*top up the saucer with water regularly.
Water the ferns regularly so the potting mix is just moist. In winter, unless there is a central heating to maintain warmth, the ferns should dry out between waterings.
Ferns are ideal for terrariums or bottle gardens. In Victorian times they were grown in glass cases known as Wardian Cases. Choose small or slow-growing ferns. Even biscuit jars are ideal!
Bag of aquarium gravel
Bag of charcoal
Free-draining potting mix such as African violet mix (one with a high organic content)
Step 1 Thoroughly clean the jar with soap and water. Rinse well and wipe out with a lint-free cloth or chamois to avoid smearing.
Step 2 Place a layer of charcoal on the base and then a layer of gravel followed by 5-8cm of potting mix. The depth will depend on the size of the container and the size of the ferns to be planted.
Step 3 Plant the ferns, using the smallest plants first. If the container has a narrow neck, use chopsticks, an old spoon tied to a stick or a cork on the end of a satay stick to make holes.
Step 4 Mist with water to water them in and add another layer of pebbles for a decorative finish. Put the lid on and place the container in a warm, light spot but not in direct sun. If the condensation is too heavy inside the bottle, have the lid half open or leave open for a while. You won't need to water again because the moisture is recycled.
Source: A Grower's Guide to Ferns, Palms and Climbers (Murdoch Books)