Fans on Seedlings
 

Has anyone confirmed that having a fan blowing over seedlings with a few true leaves actually strengthen the growing stem? If so, how long at intervals do you let the fan blow and at what velocity.

I have not noticed any effect of the fans on my seedlings this year. They all seem to do OK on their own if not over "pampered".

I think it helps.

Thigmomorphogenesis is the response by plants to mechanical sensation (touch) by altering their growth patterns. In the wild, these patterns can be evinced by wind, raindrops, and rubbing by passing animals.

Wind (I use a fan here) is a Morphogenic Stimulus and strengthens stalks by resistance as well as increasing transpiration of the plants by dehydrating the leaf surface.
The transpiration causes rapid mineral and water uptake increasing the thickness of the stem.

Using a fan also helps keep the surface of the soil dry to prevent mold, fungus Gnats and damping off.

SQWIBB
Great explanation. How long should the fan stimulate the seedlings? While the lights are on (10-16 hours) or continuously?

No fan for me, I brush mine with my hands several times per day. Same idea, keeps them stocky and strengthens stems.
Bonus, my hands smell like tomatoes :)
KarenO

[QUOTE=SQWIBB;753487]I think it helps.


Using a fan also helps keep the surface of the soil dry to prevent mold, fungus Gnats and damping off.[/QUOTE]

Ditto !!, I also add some DE on the surface, which seems to help mitigate the mold/ gnats. Also see DE as a signal of when to water- depending on the plant ( tomato vs pepper).

Timer set to 2 hrs in mid AM, and 2 hrs Mid PM during "lights ON", then I check later for watering regimen.

@Tonio, DE, I like that idea


@Muddybuckets, I have mine go on for an hour three times a day. Just changed my fan configuration this weekend, more room hanging from the ceiling.
Just be careful because the fans will dry out the potting mix pretty fast, you only need a few hours a day.



[IMG]https://live.staticflickr.com/65535/49547809787_4f7dffde47_c.jpg[/IMG]




I have also been using vermiculite as a cover on the seeds.


[IMG]https://live.staticflickr.com/65535/49547581971_3226a1d23e_c.jpg[/IMG]

I keep a small fan on the same timer as my lights - about 12 hours a day. It sits on the plant shelf and creates some vibration - I think that helps too.

If the garage temps are up and they start to get leggy I add an additional fan.

I'll add brushing them - just for the smell! Thanks KarenO!

Jeff

I am a believer in fans, but use them somewhat irregularily. Sometimes it's on for 8 hours, other times I turn it off and on for 2-4 hours at a time, as I go up and down into the basement where the lights are. I also turn the trays, or change the direction from which the fan blows at least once a day, so that the fragile seedlings don't tilt in one direction.

The stimulation definitely improves the strength of the stems, and health of the seedlings, in my opinion. I like to mimic whatever processes the plant will find in nature, and some amount of wind is a constant outdoors. But the duration of breezes, and quiet times, usually at night vary, so I also vary them in the house. The stems will be better able to bear the hardening off process outdoors if they are already used to some stress.

Thanks for all the suggestions. My seedlings are now swaying in the breeze for a couple of 2 hour sessions daily and rotated every few days. Will pick up some vermiculite for the media cover to keep the drying impact low.

I use a percentage timer, works awesome, totally enables you to control how many seconds or minutes that you want the fan to run per hour.

I stick the sprouts outside as much as possible, and have used one of Rob's refurbished old oscillating fans to blow air on them as well. I really do think it has helped them more to get sturdier more quickly.

Dense seedlings under led lights here.
Fan is mandatory to prevent mold/fungal infections. Don't know about stem thickness, but they look more like outside grown, than inside

We all have different seed starting conditions. My seed room is down under at
55-56ºF. Coolish. Holds some humidity. So small fan on 24/7 when I pot up.
Starts..., peppers, micro and a few dwarfs are upstairs for now until they
explode and need room after potting up. Fan is necessary.

I have a stand up fan with a timer dial. I set it on low and in the morning and evening when checking on the seedlings, turn the dial on for about 20-30 minutes. It provides a gentle breeze effect which combined with good lighting and cool temps makes for nice, stalky seedlings.

Yes. A fan does help immensely with making strong stems. the constant movement makes the stem cells break from the movement and repair themselves to make a sturdier stem. I have a HAF fan in the greenhouse which runs continually.
and for those who don't run ,a fan just brushing your hand over the tops of the tomatoes several times a day provides a similar benefit. it also makes you happier to smell the tomatoes.