Summer months are the active growing season for most orchids, especially if they're outside. Plants that were clinging to life indoors will spring to life outdoors in the summer.
Outdoor light is much stronger and more intense than indoors. (Midday sun outdoors can be 10 times stronger than sun that shines through a window.)
For the first couple of weeks outside, protect all your plants by keeping them in total shade - even "high light" orchids. In a couple of weeks, after they acclimate to being outside, start moving the high light plants (Cattleya, Dendrobium, Cymbidiums) into more sun. A couple hours of early morning or late afternoon sun is ideal. Dappled sunlight throughout the day also works. Always avoid direct midday sun - even high light plants will burn.
As your plants transition to outdoor growers, they'll drink copious amounts of water compared to indoors - sometimes 2-3 times more! Your watering schedule will change dramatically growing outdoors.
The good news is outdoor watering is never a problem with hydroponics.
Note: Make sure you set up your plants properly - see Setting Up your Plants for Outdoors.
Water to the "opt" marking on the gauge (that's 1/2 way up). When the gauge reads "min" rewater - no dry period necessary. Always allow enough time for the gauge to go down before rewatering however. Most plants will use up all their water in a week - and in hot weather sometimes in days.
On the other hand, if a rainy period has your orchids standing in water for extended periods of time (a week or more), force a "dry period". Using one hand to steady the plant (and holding the pebbles in place) dump out all the water in the saucer. If you're using grower trays, remove plants from the tray and pour out all the water. Don't rewater for several days. Those roots need air!
Nutrients: Your plants are actively growing and they're hungry! Apply full strength nutrients every watering. (We use and recommend Dyna-Gro "Grow 7-9-5", 1/2 tsp. per gallon.) Occassional rain showers will flush the system.
If your plants are protected from the rain, flush out the system every couple of weeks by pouring clear water (no nutrients) through the pebbles until it drains out the bottom of the pot. The garden hose works well for this.
Adding Dyna-Grow "Pro-Tek" (1/2 tsp. per gallon) to the nutrient solution during the summer month adds silicon to the mix which makes the plants more heat tolerant and drought resistant.
Temperatures: Another advantage to growing outside are those warm (even hot) summer days. Unlike houseplants, orchids welcome hot days and chilly nights. Most orchids enjoy temperatures into the 90's during the day and as low as 50-55 degrees at night.
Don't worry about hot weather. As long as your plants are protected from direct, mid-day sun and have good air circulation they'll be fine. Mother nature designed orchids to handle the heat by using the air that moves over their leaves to keep cool. If your plants are getting a breeze, high temperatures won't be a problem. A gentle shower from the garden hose always helps too.
For more on growing orchids outdoors with hydroponics:
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