| Temperature Range (˚F) | Days | Nights |
|---|---|---|
| Cool house | 61-65 | 55-61 |
| Intermediate house | 70-81 | 60-70 |
| Warm house | up to 90 | 70-75 |
In June plant growth is at its maximum. All repotting should be stopped except for summer-flowering Cattleyas. These can be repotted as soon as flowering is completed. There can be exceptions to this if necessary; plants like Phalaenopsis, Paphiopedilum, Vandaceous and other monopodial plants is a single vegetative shoot which continues in growth, from its terminal bud, from season to season. Just remember that it is harder on plants when repotted in the warmer weather, so only do so if really necessary.
The daily routine must be followed carefully. With the higher temperatures you need to keep a close eye on plants for water, fertilizer, shading, humidity, air movement and other things. Heat is needed only for young plants or delicate species. If a warm period is suddenly followed by a cold wet spell, care must be taken to avoid bacterial rot, caused by too high a humidity with the low temperatures.
Plants should be fertilized regularly if their root systems are fully developed. Orchids grow much faster and require more water and fertilizer. Modifying watering and feeding schedules as the seasons change is crucial to successful growing. Water just before the plants dry. Pay special attention to those specimens with strong new growths and active roots. Do not allow them to dry out completely. This may indicate daily watering for small plants outdoors, and will mean greatly increased watering for everything else. Continue to fertilize immediately after every second watering.
June is the month when orchids are put outside for the summer and it is the time to give the greenhouse a thorough cleaning. Check the heater, wash the pots, clean the tools, and order any supplies that will be needed. Inside the greenhouse remove algae from fiberglass and other glazed surfaces. On a cloudy morning wet the glass with water, then with a pump sprayer, spray on Physan and wait for 30 minutes. Then take a garden hose with a strong force nozzle, wash the glass down and remove any stubborn stains with a soft brush.
Only well established plants perform well outside. Keep orchids repotted in late spring or early summer in the house or greenhouse until new strong roots develop. Other plants that seem to do best when left in their regular accommodations include paphiopedilums, phalaenopsis, miltoniopsis and most often pluerothallidinae. The extremes of temperature and the bright light seem to do more harm than good. The same is true for community pots and small seedlings.
The same factors which make summer so wonderful for growing orchids can be sources of trouble. Too much light indoors or outdoors can kill a plant in a few hours. To determine if a location is suitable, place a plant there during the brightest part of the day for about 15 minutes. If its leaves are cool to the touch, the location is good. If however, the leaves are warm, move the plant to a shadier site. A window that is perfect during the remainder of the year can become far too hot during the warmest part of the summer.
Kentucky Orchid Society 