The most important considerations when cultivating airplants are their requirements for air, light, water and warmth. Plants can be placed outside in the summer in the UK to benefit from the brighter conditions, rainfall and increased humidity. Return them under glass or bring indoors in early autumn.

Tillandsia have leaves coated in specialised water-absorbent cells called trichomes which in some species are so dense they give the plants a silvery, frosted appearance. The trichomes are their primary method of obtaining moisture from rainfall or fog.

Airplants are often grown on gnarled wood, or shells and rocks to which they are glued for support. The ornamental appearance of Tillandsia and their colourful, exotic-looking flowers make them intriguing and popular plants to grow in the home and conservatories.

Ventilation

Airplants have evolved in sites which all have superior airflow. It is therefore very important to provide a well-ventilated position for plants to remain healthy.

Light levels

Tillandsia enjoy bright but diffused light, so provide light shade from direct sunshine, particularly under glass. A position in a south-facing window behind a net curtain is ideal.

Watering and feeding

• From spring until autumn, immerse plants in rainwater on average two to three times a week, allowing them to dry off in between
• Avoid using tapwater especially in hard water areas as the water contains dissolved sodium bicarbonate which can precipitate out on the trichomes and block them, preventing the Tillandsia from absorbing moisture and nutrients
• In higher temperatures and low atmospheric humidity, watering may be required more frequently; less often in cooler, humid conditions
• Misting plants in-between immersing them can help to prevent dehydration in warm conditions, but does not provide sufficient moisture alone so should not be used instead of immersion
• Avoid watering plants if temperatures drop to 12ºC (54ºF) as they can remain wet for too long
• In summer, plants can occasionally be left to soak overnight in water to which some fertiliser suitable for orchids has been added. This will ensure they are fully hydrated and able to absorb the fertiliser. Tillandsia will not tolerate being kept in water for longer periods or being kept continuously wet
• Allowing plants to dry off in between watering is very important for good plant health
• Plants should be angled facing downwards when mounted, to allow water to drain out of the centre or crown of the plant, or gently shaken after watering to dislodge any water droplets

Temperature

Plants do best if the temperature does not drop below 12°C (54°F) and can tolerate a maximum of 30°C (86°F) if relative

The amount of water vapour in the atmosphere. Different plants require different levels of humidity. Houseplants that need high humidity are best grown in a steamy bathroom, misted regularly or the pot placed in a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor, overhead watering or misting. However, high humidity can cause fungal problems, in which case open vents to improve ventilation.

Pruning

Most bromeliads including Tillandsia are monocarpic, meaning they grow to maturity, flower, set seed and then die, but not before producing offsets or young plants from the base. The mother plant once it has died completely, can be pruned away, leaving the offsets in situ to grow on; but pruning is not otherwise required.

Useful websites:

Air Plant City
Article on growing tillandsia from seed
Bromeliads
Air Plant Expert 

Offsets

Tillandsia are easily propagated by detaching offsets, although it is best to wait until the offsets have reached one third the size of the mother plant before doing so to ensure success. Once they have been detached they can be treated as for an adult plant.

Seed

Seeds of Tillandsia need warmth, moisture, light, and good air circulation for germination and survival;

• Old tights or stockings stretched over a wire frame, or chunks of tree fern fibre can be used as a substrate for germination
• Spread the seeds thinly so that they have plenty of space and are not touching as this helps when moving them on without damaging them once they have reached manageable size, as well as enabling the seedlings to grow larger
• Keep in strong but diffused light, good air circulation, high humidity and a temperature of approx. 25°C (75°F) for germination
• For the first two years or so, the plants require the same growing conditions as for germination
• Water by misting heavily whenever the surfaces of the young plants appear dry
• Feed weekly with an orchid feed or a regular liquid feed at one quarter strength
• Avoid keeping the substrate too moist as this will cause development of algae that can suffocate the young plants
• Once the plants have reached 1.25cm (½in) in height, they are ready to be separated onto individual pieces of substrate to grow on to flower

Tillandsia usneoides (originating from Southern states of USA, C. America and South America): In the wild it grows in large silvery green festoons often several metres long, from branches of trees and even other inanimate structures such as telephone lines. Produces small yellowish green fragrant flowers.

Tillandsia caput medusae (originating from C. America and Mexico): Produces silvery, sage-green linear leaves from a swollen bulb-like base. Purple flowers are produced on a reddish spike height 10-15cm (4-6in) spread 15cm (6in).

Tillandsia xerographica (originating from C. America and southern Mexico): Produces silvery green leaves that turn blush-pink in bright light. Height and spread 20-25cm (8-9in).

Rotting: Rot can cause the centre of the plant or some of the leaves to turn brown or black. It most usually occurs from water collecting in the crown of the plant, in conjunction with poor air circulation.

Dehydration: Dried out plants can occur as a combination of infrequent watering, high temperatures and low relative humidity. Plants can sometimes be revived by soaking overnight, but in the long term an adjustment to more favourable watering and growing procedures is required. Extended use of hard water instead of rainwater can also cause dehydration.

Shedding leaves: Loss of lower leaves is the result of stress such as from a change of conditions or water stress. This can also be an indication of rot (see above).

Brown or bleached leaves: This is usually the result of the plant overheating under glass in direct sunlight, and low relative humidity, causing the foliage to scorch. Provide more shading and raise the humidity around the plants to correct this problem.

Slugs and snails: These common pests can be a problem on the plants especially if they have been placed outside for the summer.