Offshore Flow
When local meteorologists use the phrase “offshore flow,” it’s going to heat up here in the San Francisco Bay Area. Orchid growers on the coast, like me, normally take advantage of the cool fog flowing off the Northern Pacific to maintain good humidity. Those moderate conditions allow many orchid varieties to grow outdoors all year. But when conditions change to offshore flow, the typical marine influence disappears. Instead of cool, moist breezes blowing from the ocean, hot, dry air flows from inland. For example, today it’s 83F (28C) in the shade, 92F (33C) on the back deck, and a desert-like 13% humidity.
Since I don’t have any automatic watering systems, that means I have my work cut out for me. With my mister bottle for indoor orchids and a hose for outdoor orchids, I spray down the plants numerous times during the day. It’s more about wetting the leaves and roots than watering the potting material. In addition, I wet down any surfaces, like the wood surface of our deck, so the evaporating water can supplement the meager humidity.
Even some delicate orchid varieties, like this Masdevallia which likes to stay below 75F (24C) all year, can handle the heat as long as there’s good humidity. Fortunately, this hot spell is only forecast to last for the weekend, so the fog can take over again soon. But for now, I have to grab my mister bottle and go…
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June 13th, 2010 at 1:31 pm
How amazing that you can keep orchids without a greenhouse? Good luck keeping them alive in the heat wave.
June 15th, 2010 at 5:42 am
Great post! Thanks!
June 19th, 2010 at 4:44 pm
This is interesting your climate is so unusual in California. Its neat that you can grow orchids outside all year.
June 21st, 2010 at 10:19 am
[…] While we often have sunny days and yes, even heat waves, the vast, chilly Northern Pacific is just a few miles away. […]
June 25th, 2010 at 12:54 pm
I read about keeping humidity up by placing pots on gravel trays with water. What about just skipping the gravel part and putting the pot on a tray of water, making sure the water level is low enough not to wick the water into the pot? Is there any reason not to do this?
June 25th, 2010 at 6:23 pm
Yes, it’s fine to skip the gravel as long as the pot stays raised above the water level. The gravel helps keep the pot raised, and can also increase the surface area available for evaporation, but gravel isn’t necessary to increase humidity. It will probably be easier to keep the water clean without gravel. also.
July 3rd, 2010 at 12:04 pm
cool post
thanks
November 20th, 2010 at 11:14 pm
[…] We’ve had November warm spells before, but when I heard Bay Area forecasters using the words “offshore flow,” I knew it was going to be a mini heatwave. Most of the outdoor orchids would be fine, and I’d […]