These orchids can be planted in orchid bark, moss or a mix (mixes might include bark, small rocks, moss, sponge rock, and even cork). Don’t even think about planting them in the soil. If your orchid is planted in bark you’ll need to water it more often than if it’s planted in moss. The bark will help the water drain with ease where the moss will hold the moisture longer. I prefer the bark or mixes which are predominantly bark because the watering is much easier for me to get right.
The seeds are generally almost microscopic and very numerous, in some species over a million per capsule. After ripening, they blow off like dust particles or spores. They lack endosperm and must enter symbiotic relationships with various mycorrhizal basidiomyceteous fungi that provide them the necessary nutrients to germinate, so all orchid species are mycoheterotrophic during germination and reliant upon fungi to complete their lifecycles.
Oncidium, perhaps more accurately the oncidium alliance, are a group of plants from South America that span a wide range of habitats. Inside the oncidium alliance there are a number of genera that hybridize freely to create what we call intergeneric oncidium hybrids. These can come in all sorts of shapes and sizes but are generally characterized by large quantities of small to medium flowers borne on a branched stem that generally forms a Christmas-tree shape. The most commonly identified Oncidium are the yellow “dancing lady” type.
Orchids have many associations with symbolic values. For example, the orchid is the City Flower of Shaoxing, China. Cattleya mossiae is the national Venezuelan flower, while Cattleya trianae is the national flower of Colombia. Vanda 'Miss Joaquim' is the national flower of Singapore, Guarianthe skinneri is the national flower of Costa Rica and Rhyncholaelia digbyana is the national flower of Honduras. Prosthechea cochleata is the national flower of Belize, where it is known as the black orchid. Lycaste skinneri has a white variety (alba) that is the national flower of Guatemala, commonly known as Monja Blanca (White Nun). Panama's national flower is the Holy Ghost orchid (Peristeria elata), or 'the flor del Espiritu Santo'. Rhynchostylis retusa is the state flower of the Indian state of Assam where it is known as Kopou Phul.
Most orchids are not heavy feeders. Many orchids bloom year after year with no fertilizer at all. During active growth, when new leaves are being produced, you may fertilize every other time you water at half the strength recommended on the fertilizer package. However, it's important to deliver water without fertilizer at least once a month to flush excess fertilizer salts from the bark mix and avoid fertilizer burn to the roots.