Department: Glass
Petra gave me a brief introduction to her Tropical Orchid House today. All her orchids are not strictly tropical, but some of them prefer warmer environments and don't mind the humidity - e.g. Pathiopedilum - the slipper orchid. The house temperature has been raised from 18°C - 20°C because it was felt that the Cattleya were not flowering enough and needed more heat to want to do so.
Coelogyne and Bulbophyllum likes lots of water. She has very big baskets of Coelogyne and they are very congested but they are good for impact and she hasn't got any bigger baskets to pot them in ad they don't like root disturbance, so she is keeping them like this, so it means she has to extra water them. Pseudo bulbs will shrivel if they are not watered enough. Vanda orchids have aerial roots and these have to be misted constantly, going from white to green will indicate that they are sufficiently watered. When they are in active growth a segment of the tip of the aerial roots distinctly turns light green to dark red. Pathiopedilum and Cattleya don't like too much water. At this time of year Petra waters or at least mists it twice per day to keep the humidity going. There is automatic underneath bench misting too, she estimates that they go off every hour.
A lot of the Vanda and Phaelaenopsis don't have proper names as they were bought in for displays and they were kept because they looked nice. Others if not sold or given away are composted. They tend not to give potted away potted ones because of the risk of cockroaches being in them. One sign to tell if a Phaelaenopsis is not an one off flowering wonder is when the flowering stem doesn't grow directly out of the leaves or if there is room for a new shoot to develop and grow. Dendrobium tends to flower on canes with leaves although there are exceptions. Thunia orchids (in Dave's house at the moment) looks like canes and new shoots develop at the end of them.
She feeds them special orchid feeds a Peters Excel Cal Mag Finisher for flowering and CalMag Grower for foliage. She feeds them once every week for four weeks and then has one week of not feeding so that the feed can wash through and not leave any deposits.
Pseudobulbs are modified stems, this name is used to distinguish them from true bulbs or corms that are a combination of stem and leaves underground, and because they grow overground. They are a storage organ. Why maybe some orchids have pseudo-bulbs and some just aerial roots maybe because the latter is where there is constant moisture and the former may have more sporadic levels of moisture. The growing media used for these orchids generally are a large bark and Bromeliad mix. Some of the orchids are potted in rockwool cubes as this helps them retain water.
Pest and diseases - thick leaved type orchids tend not to get aphids. They are prone to mealy bug and scales, the former likes to get into the cracks of the nodes and other hard to reach places. Cockroaches eat the flowers and sometimes nibble on the leaves. As many orchids are slow growing, they can be very delayed in their reaction to P & D, and usually develop black markings/ spots as a response to damage. This means they also take a long time to heal, or maybe the P & D isn't present anymore by the time one sees signs of these.