General Information
The oncidium family is very large and includes many different varieties. This instruction sheet deals with oncidium types that have thin leaves, pseudobulbs and branching sprays with flowers colored in yellow and mahogany.
Watering
Water when the mix just approaches dryness in large pots 6 inches or larger. You can check the mix for moisture by sticking a wooden pencil into the mix about 3-4 inches. When you pull the pencil out, check the wooden end. If it has turned dark in color, the mix is still wet and you should wait a day or two.
Feeding
Prior to fertilizing, water plant with clear tepid water. Dyna-Gro is the ideal brand to use as it provides all six of the macro nutrients and all essential trace minerals plants need to be healthy, grow and flower. Mix 1/2 tsp. of Dyna-Gro Grow with one gallon of water and use with every watering. To assist blooming, switch to the low nitrogen/high phosphorus Dyna-Gro Bloom formula or Mag-Pro supplement for the winter and/or pre-bloom periods.
Light
Grow in bright diffused light; east or west windows are ideal. South windows will work but one should be careful of the brilliant sun that will come in during the fall through spring months. If you have miniblinds or sheer curtains, you can break the light so that it is more diffused.
Temperature
Ideal night temperatures (fall, winter and spring months) are 60-64 F. Ideal daytime temperatures are 70-85 F.
Humidity
Humidity levels for these plants should be kept at 40% or above.
Flowering
Depending on the variety, the flowering season can be at any time of year, but it is generally heaviest in the fall and spring. Many hybrids can bloom 2-3 times per year. In order to initiate the flower spikes, it is important to grow the plant in an area where the night temperatures fall below 65 F. Usually plants growing by a window are a couple of degrees cooler than the rest of the house.
Repotting
Repot every year as the mix breaks down or the plant outgrows the pot. Carefully pull plant out of the pot. Clean off the roots of the old mix, being careful not to break the good roots. Roots which are bad and should be cut off are those that are brown and mushy or papery. Those roots which are white or tan and are firm to the touch should be left alone. Place the plant into a new pot positioning the oldest growth towards the back so there is room for the newer growth to develop for about a year.
Dividing
Oncidiums can be divided when there are 6 or more pseudobulbs. Divide, leaving 3 growths per each division.
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