Growing Bromeliads in the Greenhouse
There are around 2,000 different species of bromeliads – a fascinating and exotic-looking family of largely tropical plants which can add a striking splash of the unusual to any warm greenhouse or conservatory.
Most of them grow as a rosette of foliage, which is often variegated or banded and many kinds produce striking flowers. The majority of the world’s bromeliads are epiphytes – sometimes called “air-plants” – growing attached to trees and obtaining the water and nutrients they need to survive directly from the air via their leaves. Other forms, including the familiar pineapple (Ananas), have a much more normal lifestyle, growing in soil and some kinds – notably Fascicularia bicolour – can even be grown outdoors where frosts are not a problem.
The most natural-looking way to grow epiphytic bromeliads is to recreate in miniature the way they are found in the wild – suitable sections of old tree branches being ideal to support them. Dampened sphagnum moss can be used to form a suitable bed for the plant until it begins to anchor itself and will help keep the air around the leaves suitably moist. Small plants can often be simply wedged into natural crevices in the bark, while bigger ones may need a little additional help; gently wire them in place while they become established on their new home; the wire can then be removed, once they have. As a general rule, younger plants become anchored quickest, making them the best choice if they are available.
By growing a variety of different epiphytes on the same artificial tree you can produce a very impressive display, especially if you choose the types imaginatively to make the most of their different colours, patterns and shapes. Many kinds are suitable for use like this, including Aechmea, Guzmania, Nidularium and Tillandsia.
Epiphytic bromeliads need mist spraying daily, ideally with rainwater which has been allowed to come up to temperature; many forms are very intolerant of lime, so mains water should not be used in hard water areas.
Some kinds can also be grown in compost, though it is essential that the mix is very open and free draining or the plant can quickly develop root or basal rot. A number of varieties with particularly striking foliage are grown in this way for sale as houseplants – including the likes of Billbergia and Nidularium.
Although outnumbered by their aerial relatives, there are still several hundred different types of bromeliads which need a more conventional approach to cultivation. In addition to Ananas and Fascicularia mentioned previously, plants such as Dyckia, Hechtia and Portea are ideal candidates. Although they can all be grown in pots, they really do best when given a bit more space in the greenhouse border – provided they can get enough light. Bright light throughout the year is essential to keep these plants flourishing, which usually means supplementary lighting in the winter months, since short days and low light levels trigger a resting period in many species.
The plants need watering in the conventional way, with a little also added to the centre of the rosette in those species which form a natural container until the flower spike begins to develop.
Many kinds of bromeliads flower only once in their lifetime and then die – which botanists describe as being monocarpic – so it is as well to have a go at propagating your favourites if you can.
Most varieties can be grown from seed in the usual manner, although it is important to use fresh seed – either newly collected or bought – since the germination rate and viability tends to fall quite quickly with age.
Alternatively, the plants typically produce offsets, which can be separated and grown on to yield a new plant. The offsets of monocarpic epiphyte varieties should not be removed before they have grown to around a third of the size of their parent or they may be slow to become properly established. They should be potted up without delay in free draining compost – a mix of peat, leaf mould and sharp sand – kept at a temperature around 21 degrees C (70 degrees F) and misted regularly. Non-monocarpic offsets can be simply attached to new supports, misted daily and allowed to develop on their own under the same conditions as the original plants.
Despite their tropical origins, with a little care to get their conditions right, bromeliads can be surprisingly easy to grow and propagate in the greenhouse – most kinds asking for little more than a minimum temperature of 10 degrees (50 degrees F), adequate humidity and light. Get these relatively modest demands right and they will thrive – their exotic looks alone making it well worth the effort!