Low Humidity and dying seedlings.

[PootingDragon]

My humidity is 25 percent. I don't think that's too good for seedlings. Any thoughts on what I can do? It was 16 percent before I germinated.

I germinated about 70 seeds... one Blue Dream shriveled up and died today.

One of my Brian Berry Cough seeds seems to be getting dry on the lower portion of the stem.


This Scott's OG is experiencing the same thing on the upper portion of the stem.

 

[Pulses]

Nute burn or to hot. Lights to close

 

[OldMedUser]

Low RH isn't a big deal and neither is losing 2 out of 70. I'd be more concerned about them getting stem rot from sitting in those soggy plugs. Let them dry out and water around the edges or better yet water from the bottom by letting the cups sit in a tray of water and soak it up. A 2" seedling has a 6" tap root in most cases so there is no need to keep the surface soaked.

I have really low RH here in the winter too and use a humidifier in the grow room when vegging but it's nice now that I'm flowering and it's no problem keeping the RH between 20 and 40%.

Grow babies grow!

 

[PootingDragon]

Low RH isn't a big deal and neither is losing 2 out of 70. I'd be more concerned about them getting stem rot from sitting in those soggy plugs. Let them dry out and water around the edges or better yet water from the bottom by letting the cups sit in a tray of water and soak it up. A 2" seedling has a 6" tap root in most cases so there is no need to keep the surface soaked.

I have really low RH here in the winter too and use a humidifier in the grow room when vegging but it's nice now that I'm flowering and it's no problem keeping the RH between 20 and 40%.

Grow babies grow!

Oh shit I hadn't even thought about the stem rot. They are in coco and I've been watering every day. So I'll let them dry out for a day or two? I noticed today a lot of the stems are a bit purple. Is ghat cause for alarm?

 

[OldMedUser]

Let them dry out until the cups feel pretty light or you see a few start to droop from lack of water. Daily watering will get you stem or root rot for sure. Some stems will be purple on some strains no matter what so it's just one indicator.

Is there any nutrients in the coco at all? I like to sprout in a half and half mix of ProMix HP and their potting soil or Veg and Herb mix and there is some organic nutes in the last two so they don't need any nutes added for the first while.

When sprouting in straight soilless then I like to water with 1/10 strength nutes or some seaweed fertilizer/Thrive as soon as they are up so they have something to eat. Some people say no feed for two weeks but if there is nothing for them to feed on then they won't do as good. In a rich soil like Fox Farms then you may never have to feed until they go into flowering.

You might have to wait a week for them to need watering again and I hope you have good air circulation so they don't sit in stagnant air which would promote rot and fungus. Don't blast them with air but having enough circulation that the tops are gently wiggling around is good.

 

[PootingDragon]

Hi Old Med User,

No, I have no nutrients in the coco. I fed them .25tsp of gh nutes per gallon w/ full strength cal mag and .25tsp/gallon rapid start.

I have the area sectioned off. The cups are in a 4x4 tray with a clip fan on two adjacent corners and a pedestal fan oscillating at one end of the area.

I do want to find a way to section off the area soon. But as for now I think the circulation is adequate.

Currently my co2 ppm is 450-500 in the room. I don't have an outside exhaust system setup yet because I plan on running co2. However since I just have seedlingscright now I haven't turned on the generator. Planned on waiting until it gets its first set of leaves b4 I crank it on.

Let me know your thoughts. I have some pics here to show you what I mean....

https://www.rollitup.org/t/10-lb-goal-spydrx-plus-cindy-99-more.930794/

 

[OldMedUser]

Once those seedlings get a good set of true leaves you should up the nutes to a tsp/gal at least.

Go easy on the CalMag. They don't need that every watering. What kind of water are you using? Tap water mostly has enough calcium and magnesium in it that CalMag may not be needed and can cause problems if more is added. I use RO or distilled water only and in soilless use maybe 1/4 of the recommended dose of CalMag.

You don't need to add CO2 yet either. Plenty of atmospheric CO2 for small plants.

 

[MMJ Dreaming 99]

What kind of lights? Babies like T5/T8s.

 

[im4satori]

youshould void the cal mag for now
weight until there 8 or 12" tall before adding it

don't use any nutes until you see faint yellowing
don't use soil rich with fertilizer for seedlings make sure you are using potting soil

you've already gotten some good advise

as for humidity
its pretty easy to increase humidity
that is a bit low,,and while it may not kill them itll make it more difficult to monitor water needs which means your more likely to have an error

 

[PootingDragon]

Once those seedlings get a good set of true leaves you should up the nutes to a tsp/gal at least.

Go easy on the CalMag. They don't need that every watering. What kind of water are you using? Tap water mostly has enough calcium and magnesium in it that CalMag may not be needed and can cause problems if more is added. I use RO or distilled water only and in soilless use maybe 1/4 of the recommended dose of CalMag.

You don't need to add CO2 yet either. Plenty of atmospheric CO2 for small plants.

So my tap water is SUPER CLEAN! It's 40-50 ppm. I tried a DWC once w/o cal mag and the plants suffered hard. I'm also told the coco will draw out the calcium. U think I shud do .5 tsp/ gal instead ad the full strength?

What kind of lights? Babies like T5/T8s.

I got them under 2 4x8s but I only have 4 of the lights turned on for each one. Figured they didn't need soo much light just yet!

youshould void the cal mag for now
weight until there 8 or 12" tall before adding it

don't use any nutes until you see faint yellowing
don't use soil rich with fertilizer for seedlings make sure you are using potting soil

you've already gotten some good advise

as for humidity
its pretty easy to increase humidity
that is a bit low,,and while it may not kill them itll make it more difficult to monitor water needs which means your more likely to have an error

I'm rocking coco for this one.

 

[im4satori]

oops sorry my mistake

 

[docuM3]

The low humidity will cause extreme slow growth

 

[docuM3]

The low humidity for seedlings will cause extreme slow growth but there are other factors that one must consider like how much ppfd and the spectrum of light. If the spectrum of light is high then don't dare put that led light 12", 18" or even 24" put it at the top. High spectrum and high ppfd over 150 is to much and will pause growth plus the low humidity will have leafs looking curled in middle and etc, the leaf will just look unhealthy. That's because low humidity the plant is running through water it cant transporate causing u to keep watering to keep soil moist giving over watering and the plant having that high light just causes to many problems. Look at the whole picture and trually understand your growth. If it's growing slow raise the lights to top of tent and leave it, get humidity up to 65% for seedlings stage first 30 days if u haven't stunted them otherwise it will be 2 months and your still in seedling stage. Get a led light with a pat of 157 or less, raise to top of tent, ppfd should be around 100-130 and 65% humidity and she will blast out of seedlings stage.

 

[OldMedUser]

So my tap water is SUPER CLEAN! It's 40-50 ppm. I tried a DWC once w/o cal mag and the plants suffered hard. I'm also told the coco will draw out the calcium. U think I shud do .5 tsp/ gal instead ad the full strength?

With coco I'd go full strength. The ProMix HP I use has lots of dolomitic and calcitic lime added so I don't bother feeding any Calmag for quite a while as there is lots in there already plus whatever there is in the nutes themselves. Personally I think calmag is vastly over-rated and seems like everybody thinks it's some sort of magic elixir. I never even started using it until about 5 years ago and never saw signs of low Ca tho saw low Mg in DWC and Epsom Salts fixed that up fine.

 

[OldMedUser]

The low humidity will cause extreme slow growth

We have chronic low humidity here and I don't have growth problems with my seedlings. 20-30% RH is pretty much the norm here in the north. Can hover around 50 during our short summer.

 

[Herb & Suds]

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