Growing Orchids Outdoors

A mounted Laelia orchid hanging from an arbor in Orinda.

What orchids can survive outdoors year-round in zone 9B / Sunset zone 14 — the conditions that distinguish our Lamorinda microclimates?

A select few can make it through our winters — and summers. Depending on where you live, most will need to be covered and/or moved closer to the house once the temperature goes below 40 degrees, especially when conditions are also wet.

Terrestrial orchids planted in the ground sometimes do better than those in pots, because they’re better insulated. However, orchids in pots drain better, because orchids with roots in standing water and, well, mud are not happy — especially in temperatures under 50. Pots also equal portability — being able to move an orchid closer to an outside wall of your home can make a big difference. The best place for a chilled orchid is in front of a sliding glass door, where the most radiant heat exists during the coldest hours of the morning.

Cymbidiums in pots are likely your best bet. But even they can suffer when the thermometer drops under 40, especially when they have flower spikes in mid/late winter. Over the past couple winters I’ve resorted to wrapping the buds in layers of paper towels enclosed by rubber bands, then covering the entire plant in frostcloth.

The question is often one of duration. One 38-degree night? Maybe okay. But two or three, with no fabric to protect the plant from frost? That could be a problem.

A Masdevallia hybrid in a teak basket.

 

 

 

 

 

 

 

 

 

 

I’ve had good luck with mounted Laelias (although they can require extra effort to keep moist in summer) and, to some degree, Masdevallias. The latter, when in pots, will need to be kept fairly dry — most masdevallias can handle cooler temps, but not cold AND excessive moisture. Even cooler-growing species will need to be kept close to the house when the chill clamps down overnight.

There are other members of the Pleurothallid alliance (cousins of Masdevallias) that are more robust. Certain Restrepias, for example, do fine as long as (yes, again) they’re within a few feet of the house.

Another important element of raising orchids in colder climates is to stop fertilizing in late summer. It’s not wise to force new, tender growth when the nighttime temperatures are heading to the low fifties. I generally stop fertilizing in late September, with the exception of Cymbidiums — I switch to a 6-30-30 formula, especially if they’ve yet to develop flower spikes. If they do, I stop fertilizing completely.

I’ve been growing outdoor orchids in the Bay area for 25 years, and in the East bay for 10. Through experimentation and trial and error I’ve arrived at certain species and hybrids that can make it through the worst our climate can deliver. Contact me at paul at dobiemeadows dot com if you’d like to discuss which outdoor (and indoor) orchids can survive — and which can thrive — in our challenging conditions.

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