Windowsill Growing: how important is air movement?

[Blueszz]

I've been away from OB for several years after I had to give up my collection. Back then I grew most of my orchids in a enclosure with artificial lighting. I had 2 small fans running for air movement.
The reason I build that setup was lack of space in my windowsill

Recently I bought some new orchids and I've been reading about them. Several times I read that (strong) air movement is important.

Currently I only have 4 orchids and next week 5 will be added to my small collection (shipment on Monday). That's not enough to make an setup with artificial light, for now. Not enough so use that old setup again.

I might build something in a few months though. Still brainstorming about the layout.

Back to my question. How important is air movement for the orchids indoors, the ones in the windowsill and the ones pulled away from the windows? And I don't mean the rising hot air from the heating (which is detrimental).

Indoors, on the "windowsill" I never used a fan, but I'm thinking about one running oscillating towards the orchids.

Is it only beneficial or will it harm the plants?

It's all about these species:

• Coelogyne cristata
• Restrepia guttulata
• Sarcochilus fitzgeraldii
• Tolumnia variegata var. rosea
• Dendrobium densiflorum
• Haraella odorata
• Neofinetia falcata
• Paphiopedilum lawrenceanum
• Phalaenopsis pulchra

[estación seca]

I don't think it's necessary for plants growing on a windowsill. A fan may help prevent sunburn or heat damage from radiators.

[Blueszz]

Originally Posted by estación seca

I don't think it's necessary for plants growing on a windowsill. A fan may help prevent sunburn or heat damage from radiators.

The reason I consider air movement with a fan is that plants nearby my south faced window alway get spider mites. My guess is that stagnant warm air causes this.
Humidity is 69% without humidifier. Seems ok to me although I also read humidity isn’t a factor in developing a spider mite infection.

As you realize, August isn’t the time for growing in a south faced windowsill. I pulled my plants away from the window, far enough to avoid harsh sun on them.

October they can go in the windowsill and April is time to pull them away from the window.

[estación seca]

Looking more closely, most of your plants are highly susceptible to spider mites. Spider mites prefer warm temperatures and low humidity. When relative humidity is above 60% they are much less active. The air next to a south window may have much lower humidity than does the rest of the room because the temperature may be much higher. Of course you are quite far north, so a sunny south window may not be as hot as it would be farther south.

An excellent way to control spider mites is to wet thoroughly all the plant surfaces every 1-2 weeks. This is easier with a small collection. It could be done in a shower or at the sink.

Phals are shade plants. Most Restrepias are cooler growing cloud forest plants desiring shade and very high humidity. Mounted Tolumnias would be expected to do well in that window if watered frequently (daily) and allowed to dry rapidly. Neofinetias might be at risk of sunburn after long cloudy spells. Den. densiflorum should do well in that window but is very susceptible to spider mites. I haven't grown the rest.

[Blueszz]

Never thought of lower humidity close to that south window. Good one! That window is hot during a sunny summer!

I'll keep monitoring the humidity at the location the orchids are now.
I have a humidifier so can keep the humidity up if I need too.


I'm lucky to say that I had spider mites on most of the houseplants close to that window, but never saw them on my orchids. Been lucky or... I don't know.

Thoroughly wetting the plant surfaces can be risky here as the medium might stay too wet for too long. That needs repotting. Let's see how it goes before I repot all the new ones. But a medium that dries faster is something to keep in mind if I run into problems with spider mites.

(I already took the Haraella out of the pot to find soaked compacted sphagnum).

For now the windowsill is way to hot and bright.

We had terrible summer weather, for the past 2 weeks, fall like. Raining cats and dogs and storm. But next week we'll have summer days and nights again.

I also grew the orchids always as much as possible outdoors, that might have helped avoiding spider mite infections too. If the weather allows some of the new ones will go outdoors asap.

Thank you for your help, it's highly appreciated.

[Ray]

The idea behind air movement is the eliminate pockets of humid, stagnant air, as they can be great incubators of bacterial and fungal infections. In a home environment with reasonably modern HVAC systems, that is highly unlikely.

[greyblackfish]

I have not had problems with dendrobiums or cattleya on my window sill. It’s not my preferred location. They hottest summer days In July to September tend to kill our phals as it’s a bright and hot southwest window. They don’t get direct sun but it’s still a problem to the phals specifically. My oncidium also don’t seem to enjoy this window. The air circulation seems to be okay even though the temperature is usually kept pretty warm in this current house. The thermostat is kept at a constant 79-80 f and no air blows on the windows directly.

[Blueszz]

Originally Posted by greyblackfish

I have not had problems with dendrobiums or cattleya on my window sill. It’s not my preferred location. They hottest summer days In July to September tend to kill our phals as it’s a bright and hot southwest window. They don’t get direct sun but it’s still a problem to the phals specifically. My oncidium also don’t seem to enjoy this window. The air circulation seems to be okay even though the temperature is usually kept pretty warm in this current house. thermostat is kept at a constant 79-80 f and no air blows on the windows directly.

I have south windows and north windows, one north window is shaded because of a roof above the balcony. That is where I grow most of my orchids during late spring and until early fall, outdoors. Most will get early morning sun and late evening.

Today I brought my Restrepia back indoors as the amount of light was too much for it. Leaves coloring reddish. Need to make a tiny shade house for it. Miniature

Until October I can’t use the south window to grow. Way too hot and bright. I’m not sure yet what I’m going to do, using a fan or not once I’m going to use that windowsill. Or using artificial light away from the window.

Most orchids I grow right now are new to me, I have to figure out what they like most.

[greyblackfish]

Ah yes maybe direct light from a south facing window might be too much. If somehow you can filter the light then your orchids will probably do fine. Some of my orchids have turned reddish as well but it hasn’t negatively affected them. Also I’ve found that the reddish hue doesn’t happen as much of the orchid has been slowly acclimated to that location. This year I’ve carelessly thrown my dendrobiums outside in a direct sun location in close to 100 degrees f conditions and they’ve been badly burned. I’m lucky that they are still alive.

I have my coel cristata hybrid and cymbidiums growing on my window sill and they are doing well despite the said need for lots of air flow.

---------- Post added at 05:14 PM ---------- Previous post was at 05:10 PM ----------

Also I’ve used a north facing window before but it was too dark. Not even my phals did well.

[Blueszz]

Originally Posted by greyblackfish

Ah yes maybe direct light from a south facing window might be too much. If somehow you can filter the light then your orchids will probably do fine. Some of my orchids have turned reddish as well but it hasn’t negatively affected them. Also I’ve found that the reddish hue doesn’t happen as much of the orchid has been slowly acclimated to that location. This year I’ve carelessly thrown my dendrobiums outside in a direct sun location in close to 100 degrees f conditions and they’ve been badly burned. I’m lucky that they are still alive.

I have my coel cristata hybrid and cymbidiums growing on my window sill and they are doing well despite the said need for lots of air flow.



---------- Post added at 05:14 PM ---------- Previous post was at 05:10 PM ----------

Also I’ve used a north facing window before but it was too dark. Not even my phals did well.

Most of my orchids need cooler temperatures and are way better off outdoors (for now). Once indoors they'll go in an unheated room, south faced windowsill. I keep them outdoors as long as possible. Not the warm growing plants of course.

How do you make sure your Coelogyne and Cymbidiums get a temperature drop when it's growing in your windowsill?