One is more likely to grow these graceful plants in a conservatory than a greenhouse as they tend to be on the large side and are very much a decorative plant to form a backdrop for other plants in a display.
They are easy to grow but are prone to becoming dry at the tips of their leaves. This is caused by dry air. If a conservatory is to be a room for plants as well as for people it is essential to think about how decorations and furniture can be tied in with the need to keep the air humid by damping down or spraying. There must also be adequate provision for shade if leaves are not to be scorched. Another scourge of palms is red spider mite which are encouraged by dry air. A constant vigil must be maintained to spot and treat this pest before the palms are ruined. Remember that spraying under the leaves regularly will discourage them. In the wild, palms grow very large and the specimens we grow are only juvenile forms which are much more tender than the palms we might see along the Mediterranean coast in full sun.
Some palms such as Chamaerops, Livistonia, Phoenix and Trachycarpus can tolerate cool conditions. Apart from Phoenix these are also all palms that have fan shaped leaves. The other palms need warm temperatures to do well. I prefer to pot them into a loam-basedbecause as they are large plants and will need a lot of water peat-based mixes will become drier, lighter and easier to knock over. Watering palms is a case of allowing the surface to become dry between waterings but not for longer than a day.
Trachycarpus is able to grow outside in the milder parts of Britain so I would give this one a miss for the conservatory. Washingtonia, Livistonia and Phoenix are very majestic but grow easily as wide as they are high and have quite stiff leaves. They are probably the most tolerant of dry air and bright light. They will certainly lend a Mediterranean air to the area they inhabit. For a soft palm that is more upward growing, graceful and elegant Howea belmoreana which used to be called Kentia is the best choice. These will reach a good 2.5 m (8 ft) tall and need to be warmer, more humid and slightly shaded in summer. For a smaller palm I would recommend Chamaedorea elegans which used to be Neanthe and is widely referred to as the Parlour Palm. This has a nasty habit of turning yellow if in full sun during summer or not fed sufficiently. There will come a time when they have outgrown their attractiveness. Palms cannot be pruned as they will not shoot from places lower down on the stem. Rhapis excelsa is a super little bushy palm from Japan. R. e. ‘ Variegata’ looks great potted into a Japanese style glazed pot. Although able to do well in a cool house it will do equally well in warm or even tropical conditions.
If you have a warm or tropical house you will be able to grow one of my favourites which is Caryota mitis the Fish Tail Palm from Burma and Malaya. The leaflets really do resemble the tattered edges of a fish’s tail in a most unusual and attractive way. Offsets are produced around the base of the plant. This is quite common with palms and when they have grown about three leaves with hopefully a few roots of their own they can be detached and grown on. Do not be dismayed by heights of 4.5-7.5 m (15-25 ft) being quoted in books as this is only reached very slowly and only usually in the wild. Before yours gets anywhere near that you should have some offsets to provide newer, more sensibly sized, plants.
I know they look really nice but I would avoid buying one of those palms growing out of a coconut on the surface of the compost. There have been a lot offered for sale in recent years and I have not seen one which was not infected with red spider mite. For some reason they seem to love them more than any other palm. Even a clean looking plant from a good garden centre may be harbouring eggs which will hatch out and infect all your other plants.
It is possible to germinate palms from seed but it can be a painfully slow process. Soak the seed for at least two hours in warm water before sowing. Use a peat-based seed compost and place the pot in the dark at 24°C (75°F) to germinate. Keep this moist and occasionally dig into theto see if a root has been produced. If it has it is best to pot on to a deeper pot so that there is room for this root to grow. A shoot will follow shortly.