Fans on Seedlings

MuddyBuckets · February 16, 2020

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".

SQWIBB · February 16, 2020

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.

MuddyBuckets · February 16, 2020

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

KarenO · February 16, 2020

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

Tonio · February 16, 2020

Quote:

Originally Posted by SQWIBB

I think it helps.

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

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.

SQWIBB · February 17, 2020

@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.

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

jtjmartin · February 17, 2020

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

ddsack · February 17, 2020

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.

MuddyBuckets · February 17, 2020

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.

biscuitridge · February 17, 2020

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.

imp · February 17, 2020

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.

Nematode · February 19, 2020

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

oakley · February 19, 2020

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.

Father'sDaughter · February 20, 2020

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.

clkeiper · February 21, 2020

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.

February 16, 2020	#1
MuddyBuckets Tomatovillian™ Join Date: Sep 2015 Location: Eastern/Coastal NC 8b Posts: 192	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".

February 16, 2020	#4
KarenO Tomatovillian™ Join Date: Oct 2012 Location: Vancouver Island Posts: 5,931	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 Last edited by KarenO; February 16, 2020 at 11:30 PM.

February 17, 2020	#8
ddsack Tomatovillian™ Join Date: Jan 2006 Location: Northern Minnesota - zone 3 Posts: 3,231	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. __________________ Dee **************

February 17, 2020	#11
imp Tomatovillian™ Join Date: Apr 2009 Location: Wichita Falls, Texas Posts: 4,832	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. __________________ I'm not a complete idiot, some parts are missing.

February 21, 2020	#15
clkeiper Tomatovillian™ Join Date: Nov 2011 Location: ohio Posts: 4,350	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. __________________ carolyn k

February 16, 2020	#2
SQWIBB Tomatovillian™ Join Date: Jan 2018 Location: Philly 7A Posts: 739	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.

February 17, 2020	#7
jtjmartin Tomatovillian™ Join Date: May 2016 Location: Williamsburg VA Zone 7b Posts: 1,110	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

February 17, 2020	#10
biscuitridge Tomatovillian™ Join Date: Jan 2014 Location: washington Posts: 498	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.

February 19, 2020	#12
Nematode Tomatovillian™ Join Date: May 2012 Location: massachusetts Posts: 1,710	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

February 19, 2020	#13
oakley Tomatovillian™ Join Date: Jun 2015 Location: NewYork 5a Posts: 2,303	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.

February 20, 2020	#14
Father'sDaughter Tomatovillian™ Join Date: Nov 2011 Location: MA/NH Border Posts: 4,919	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.