This article was originally printed in 1995 in the American Orchid Society Bulletin, part one 64(9):976-985, and part two 64(10):1102-1107.
Charles and Margaret Baker
For many years growers used the name Miltonia to refer to those plants known as the 'cool growing' or 'Colombian' Miltonias. The other members of the genus, mostly from Brazil, were pretty much ignored. Now that the most well known and commonly grown plants have been reclassified to the genus Miltoniopsis, those other Miltonias, the Brazilian species, are left as the only Miltonias.
These Brazilian plants are members of a rather small genus which, according to current thinking, is made up of nine species, Miltonia anceps, M. candida, M. clowesii, M. cuneata, M. flavescens, M. kayasimae, M. regnellii, M. russelliana, and M. spectabilis. Two additional species, which were once considered Miltonias, M. schroederiana and M. warscewiczii, have been reclassified in recent years. They are now known as Oncidium schroederiana and Oncidium fuscatum.
Miltonia species have large, attractive, long lasting flowers and they are generally considered easy to cultivate, but for some reason they have been ignored by most of the orchid community. Some feel that their lack of popularity is probably because they do not look like their more famous and widely grown cousins, Miltoniopsis (pansy orchids). We feel that there must be more to it than this, however. More than 100 years ago, in his coverage of Miltonia candida, Veitch said, "Long known as one of the handsomest of the Brazilian Miltonias, but of which nothing has been recorded of its habitat or of its discovery". About Miltonia cuneata he said, "The first notice of Miltonia cuneata occurred in 1844, at which date it was cultivated by Messrs. Rollisson at their nursery at Tooting; many years afterwards it was sent to M. Verschaffelt's horticultural establishment at Ghent by a French correspondent, M. Pinel, from Brazil. Beyond this not a scrap if information is forthcoming respecting its habitat, its discoverer, or the date of its introduction". He reported this same lack of information for the other species as well, and today there has been very little added to this "wealth" of knowledge.
We are indebted to Louis Hamilton Lima, an AOS member in São José dos Campos, Brazil, for the information he was able to provide on the habitat location and elevation for most of the Brazilian Miltonia species. Without his assistance, we simply could not have selected representative climatological data for these species.
Not only has there been a lack of information about these plants, there has also been some erroneous information floating around. For many years they were referred to as, "the warm-growing Brazilian miltonias" in order to differentiate them from the "cool-growing Colombian miltonias". We now know that the cool-growing Colombian miltonias are, for the most part, actually intermediate to warm growing; and equipped with accurate habitat location and elevation information, we are able see that the warm-growing Brazilian miltonias are, for the most part, not actually warm-growing. Instead, most require cool to intermediate conditions.
Miltonia species have not received the overall attention they deserve, but they are usually found in many of the more complete collections. In addition, specialty breeders have occasionally included them in hybridizing programs. The Brazilian species hybridize easily and well with most Brassia species, which also have 60 chromosomes. On the other hand, Miltonia warscewiczii (now Oncidium fuscatum), which has 56 chromosomes, crosses easily with many Oncidium species. For readers interested in exploring hybridizing with Miltonia species, there have been several excellent articles published on this subject over the last 20 years or so. They are listed in the bibliography at the end of this article. For the most part, the progeny generally possess hybrid vigor, and they tolerate a wide range of temperatures. As a result, they are usually very easy to grow and flower.
Common Cultural Needs
Although Miltonia species are found over a large region, several cultural requirements are common to all the species. We will first look at these common needs, and then take a closer look at the specific requirements of each species.
LIGHT: 1500-3000 fc. Strong air movement is recommended at all times, especially if plants are grown at higher light levels. Growers report Miltonias grow well even in the bright light required by Cattleyas, but their leaves tend to be very yellow when light is high.
HUMIDITY: 80-85% year-round. Not only is rainfall relatively high in the region, but humidity is high because of moisture laden southeast trade winds that blow inland from the ocean. Low clouds, fog, and mist frequently develop from condensation when the warm moist air cools as it is lifted over the mountains. Thus, large amounts of moisture, which is not necessarily reflected by rainfall totals at nearby weather stations, is available to plants growing in the region.
WATER: Although rainfall patterns vary somewhat in the various habitats, the common thread is the absence of a truly dry season. Rainfall in most areas is moderate to heavy from spring into autumn, with somewhat lesser amounts in winter. While rainfall in most habitats is lower in winter, the condensation previously discussed results in additional water being available from frequent mist and heavy deposits of dew.
Cultivated plants should be watered often while actively growing. Water should be gradually reduced in autumn when growths are mature and flowering is completed. During winter, water should be reduced even more, especially for plants grown in the dark, short-day conditions common in temperate latitudes. However, plants should never be allowed to dry out completely. In most growing areas, these conditions may be provided by occasional early morning mistings with a light watering given every two weeks or so, particularly if a period of bright sunny weather is forecast. Fertilizer should be reduced until water is increased in spring.
FERTILIZER: A balanced fertilizer, mixed at 1/4-1/2 recommended strength, should be applied weekly during periods of active growth. Many growers use a fertilizer with lower nitrogen and higher phosphate in late summer and autumn. This improves blooming and encourages new growths to harden before winter. Pots should be leached every few weeks to prevent salt buildup, especially when fertilizer is being applied most heavily. Plants should first be watered normally to dissolve any accumulated salts. An hour or so later, the medium is flushed with water equal to about twice the volume of the pot. Year-round leaching is important in areas with heavily mineralized water.
GROWING MEDIA: Because most Miltonia species have rather rambling growth habits, plants are more easily managed when mounted on slabs of cork or tree-fern fiber. However, high humidity must be maintained, and water should be applied at least daily during the summer. Mounted plants may even need to be watered several times daily during particularly hot, dry weather. Most growers find it difficult to keep mounted plants moist enough in summer, so they are usually grown in baskets or shallow pots filled with an open, fast draining medium based on fine fir bark or tree-fern fiber. Normally, varying amounts of materials such as perlite and charcoal have been added to produce a medium that drains rapidly but still retains some moisture. Undersized pots which are only large enough to hold the roots and allow one to two year's growth should be used. Because the continually moist medium starts to break down fairly rapidly, plants usually grow better if repotted every year. Repotting should be done just as new root growth is starting so that plants become re-established in the shortest possible time.
Each grower should experiment to find which combination of materials works best in their particular growing area with their particular watering practices. For example, tree-fern fiber holds moisture better and does not break down so rapidly, so it seems logical to use it for plants that should not dry completely between waterings. And yet, Miltonia species grow better for us in a fir bark medium.
We have also had excellent results growing in shallow pots and baskets with loosely packed New Zealand sphagnum moss. The drawback to this medium is the cost of the material and the fact that it breaks down so rapidly that plants must be repotted every 9-12 months. We have come to believe that most orchids may be grown in about any medium the grower chooses to use if watering is adjusted to match the medium and the conditions in the growing area.
The following information includes a brief description of the plants and flowers, habitat location and elevation, and specific cultural requirements for each of the Miltonia species.
Miltonia candida, M. clowesii, M. cuneata, M. flavescens, and M. spectabilis are all found in the State of Espirito Santo northeast of Rio de Janeiro, Brazil. Also, they all grow at about the same elevation. Therefore, in the interest of saving space, climate data for Vitoria has been used to indicate probable cultural conditions for all of these species.