Miltonias have gained a reputation for being difficult to grow. However, their culture is basic and rewards of growing this beautiful genera are many. Below are a few notes on successful culture of these plants.
Light
Miltonias should be relatively shaded. Direct sunlight burns the thin leaves within a short period of time. However, the warmer-growing types prefer more light than their cooler-growing relatives. The cool-growing species need approximately 1,200 foot-candles, while the warmer-growing species require closer to 2,000 foot-candles.
Water
Water must be plentiful and the medium must drain perfectly. In their native habitat, the plants are drenched almost daily and, because of this, they are intolerant of salt buildup, so leaching every 6th or 7th watering is important when growing in pots. When they are not getting water or humidity, the leaves have a tendency to grow with accordion like pleats. The warmer-growing miltonias should be grown like Cattleyas; allow them to approach dryness between watering. They also tend to be slightly more tolerant of salt buildup.
Temperature
The ideal day temperature should be kept below 85ºF and above 68º F if possible. If the temperature rises above this limit, shade and humidity should be increased. The night temperature should be in the 52ºF and 60ºF range. A differential of 20ºF between day and night temperature is very beneficial.
Humidity
The relative humidity that is recommended is 50 to70%. As the temperature during the day rises, with increased light intensity humidity should be increased. Miltonias appreciate being “fogged” on sunny days. In nature these plants are found in cloud forests where it rains daily.
Fertilizing
Feed one quarter strength of 20-20-20 fertilizer every other watering. During active growing season this may be applied at every watering.
Potting
These plants are grown in many different mixes and containers. Whichever medium is used, it should retain moisture and at the same time provide excellent drainage. Generally the mix is composed of fine fir bark, plus additives such as approximately 10% small sized charcoal, and 15% perlite. Miltonias like to be repotted yearly during the cool season, preferably when the new growth is approximately 2″ tall. Miltonias resent over-potting. A small pot with good drainage will allow the free watering that miltonias prefer without the consequences of a soggy mix. Use plastic pots if possible. Miltonias are very susceptible to root damage caused by salt accumulation of which occurs in clay pots. Miltonias prefer to grow into sized good clumps before dividing. It will produce more, and better flowers if left in a large clump.