Tag Archives: greenhouse effect

why a greenhouse?

I find that I’m asking myself whether I need the greenhouse anymore. Left over from an obsession with warm-growing orchids a couple decades ago, it sits in the middle of some prime real estate in the every-shrinking back yard.

Its current incarnation is more shed than greenhouse, with bags of potting mix and pots taking up most of the space. Still I continue to use it for some propagating. Because of the famous greenhouse effect temperatures inside during the daytime can climb ten to twenty degrees higher than outdoors–and that’s with heavy shadecloth on the western exposure. Even at night it stays a little warmer than the outdoors. Before sunrise during a cold snap a week and a half ago I looked at the thermometer inside: 42 degrees. Pretty cold, but it was but four to five degrees higher than a nearby thermometer outside.

The new patch of lettuce outside. Where's the lettuce?
Here's a little recycled sixpack that I seeded with lettuce five days earlier. Unlike the bare patch outside, the seeds are germinating.

The extra warmth can help seeds germinate a few days earlier than outdoors. And once the plants are up they can grow quite a bit faster. The warm spa temperatures inside the greenhouse, combined with some protection from marauding nature, can give you a leg up on the season.

I showed this photo of germinating bladderpods a couple of weeks ago. These plants are less than two weeks old.
And these are the same bladderpods last night, showing lots of luxuriant growth. I'll be repotting these soon and getting them ready for planting in the garden.

If you’re occasionally impatient like me it’s nice to see bigger plants sooner.

And this last photo shows another advantage of the extra warmth. These are yearling seedlings of the North American pitcher plant, Sarracenia. All three pots were started in the greenhouse a year ago, but the one in the middle spent most of the summer outside in strong sunlight. These plants are supposed to like the intense light, but you can see that they were more partial to temperatures that reminded them of the South than intense sun. For plants that ordinarily take five years to mature, it’s looking like the extra warmth can take a year or two off of the usual time. It’s cool to have a greenhouse to save a few weeks but having it help shave one or two years is pretty persuasive.

So as I talk myself through all this it’s looking like I’ll still want to have some sort of greenhouse, even in Southern California. But it might not be this really inefficient and poorly located greenhouse. And did I mention that the current building has termites?

The replacement might be separate little structures. Maybe they could be enclosed carts and have wheels so that they could be repositioned to take advantage of the best sun angles. And if they’re on wheels they could be stuck in a corner of the yard if they’re not being used for propagation. And something like a cart wouldn’t waste space on aisles to walk down.

Well, there are lots of possibilities, and I’ll be thinking about what to do. I’m one of those people who likes to stare at a problem for a long time, but maybe in a few months you’ll be reading about the next big garden construction project.

in the greenhouse, or, the dictator's wife

greenhouse-euphorbia-outsideI was in the greenhouse Friday morning, watering some pots of seedlings. It seemed funny for a second, because outside the greenhouse it was raining. If I hadn’t gone in there with the hose that morning, the seedlings would have died in the desert for lack of water.

(Left, a Euphorbia characias ssp. wulfenii outside the greenhouse, blooming away in the rain.)

I used to grow and breed phalaenopsis orchids in the greenhouse. It was gonzo amounts of work to keep up with repotting hundreds of plants. And trying to concoct an environment that would fool the orchids into thinking that they were in the lowlands of the Philippines instead of the flats of Southern California wasn’t that easy either. In addition to all the work, the greenhouse was an energy pig, taking as much natural gas to heat as the entire house.

So, end of orchid obsession. End of heating the outdoors and wasting all that energy. (The New York Times has a recent piece on a couple who decided to build themselves a greenhouse. Their heater hasn’t arrived yet, but they’re already way over budget.)


Now that the tropical orchid episode of my life has ended the greenhouse is only heated by the sun via the greenhouse effect. At this time of year it’s handy to have a spot that will help give young plants a head start on spring. That’s pretty much how I use the greenhouse now.

greenhouseclutterAnd, um, yes, for a place to store garden clutter. Sort of a garden shed with windows…

greenhouselookinginFortunately the windows are an opaque fiberglass, so all the mess inside is obscured. Maybe even a little mysterious and poetic. Here are some potted plants as seen from the outside.

As I was watering the plants in my little artificial outdoor desert I thought back to the 1980s. One the stories from the news that has stuck in my brain all these years was a report on Michèle Bennett, the wife of Haiti’s dictator, Baby Doc Duvalier. The couple was bad news all around, and one of Michèle’s vices was that she’d refrigerate a part of the palace so that she and her friends could strut about in the fur coats that they collected. (Compared to her husband’s brutal ways, it all seems pretty minor, of course.)

Mink and fox and chinchilla coats in Haiti. About as rational as a greenhouse full of warm tropical orchids in San Diego, I thought.

I guess we all want a little of of what doesn’t come easily or naturally. But in an age of a growing awareness of the need to live greener it’s good to stand back and see what we really need.