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seeds Heat mat bad for seedlings?

W

WalkingStickMan

Hi all,

I have a few seedlings that have popped up, however the majority are still in the process of germinating and have not broken the soil yet. Will the seedlings that have sprung up be hurt by my leaving the heat mat under my tray in order to help the rest of my seeds continue to germinate?

Thanks for all of the help on this board. What an awesome resource!
 
I leave my seedlings on the mat as long as I can. It's about 30degrees here...inside its obviously warmer but not THAT warm. I believe the heat mat says that it increases the degrees by 10 degr higher than the temp in the room- so it shouldnt be bad for them unless your room is already extremely warm.

Also, the heat can and will create mold if theres alot of moisture (which there should be) in your containers. I solve this problem by just adding more dirt to the top of the dirt levels and because it doesnt have light it stops growing, or so ive been told. Also, try to let the top off for five or ten mins ever so often so it gets fresh air.

Just my experience hope it helps!

xox Nicole
 
Leave the tray on the heat mats, that's what they're used for, an aid in germination. Let the other seeds sprout. I do few things, say since only a few seeds popped I'd remove the dome from the tray and place it under the lights....close to my T8's. I mist the top of the medium. You need to keep that moist, not wet. I also lift up a corner of the flat insert and poor a 1/2" of water in the bottom of the tray. That helps take care of the down spiriling tap roots from the emerged seedlings. The medium will wick up the water. I occasionally lift up the flats to check the weight. If too light they get watered, or I peek under the insert to see if the tray is dry.

Good luck with the rest of your seedlings

Greg
 
If the seedlings have just popped they should be fine. The cotyledons (seed leaves) are pretty strong and you have about a week before they will start growing true leaves. If the true leaves are growing all curled up you might have too much heat on your roots. This happened to me this year.You then have three options. The first is to regulate your heating mat with a thermostat (~$25) and keep the roots warm but not hot. I find the bottom of my plugs can get in excess of 90F with my heating mat, but the surface stays a cool 70F, but my thermostat can help regulate root temps. The second option is to add something between your heating mat and seed tray to lower the temps. Sand works, cloth can work if your mat isn't too hot, but this is pretty inexact and you might drop temps lower than you want this way. The final way is to just take out the seedlings to pots and let the remaining seeds pop on their own with the heating mat on full blast.

Good luck.
 
Nicole said:
I leave my seedlings on the mat as long as I can. It's about 30degrees here...inside its obviously warmer but not THAT warm. I believe the heat mat says that it increases the degrees by 10 degr higher than the temp in the room- so it shouldnt be bad for them unless your room is already extremely warm.

Also, the heat can and will create mold if theres alot of moisture (which there should be) in your containers. I solve this problem by just adding more dirt to the top of the dirt levels and because it doesnt have light it stops growing, or so ive been told. Also, try to let the top off for five or ten mins ever so often so it gets fresh air.

Just my experience hope it helps!

xox Nicole
Click to expand...
i noticed one of my seed starting trays started growing mold, so you suggest to put more soil over? thanks for your input
 
Thanks Matt,

I currently have a thermostat set at 82 F, with the probe located at the edge of the tray, and I know that my temps towards the middle of the tray get about 5 degrees hotter. I might have to play around with temps that are OK for both the seedlings that have already sprouted as well as the still germinating seeds.
 
WalkingStickMan said:
Thanks Matt,

I currently have a thermostat set at 82 F, with the probe located at the edge of the tray, and I know that my temps towards the middle of the tray get about 5 degrees hotter. I might have to play around with temps that are OK for both the seedlings that have already sprouted as well as the still germinating seeds.
Click to expand...

You're a-okay with those temps. In fact, probably ideal. I use a heat mat for germination and our home is between 69-75F during the winter. It runs it up to about where it needs to be, and I usually get my first "pops" in 3-4 days. That includes superhots from good seed stock.
 
Eephus Man,

When do you remove your heat mat? My concern is that, while I keep the heat on for the rest of my seeds to pop, the heat will be detrimental to the seedlings that have already come up. Can my seedlings handle the mid-80 F temperatures while I wait for the rest of my seedlings to come up?
 
WalkingStickMan said:
Eephus Man,

When do you remove your heat mat? My concern is that, while I keep the heat on for the rest of my seeds to pop, the heat will be detrimental to the seedlings that have already come up. Can my seedlings handle the mid-80 F temperatures while I wait for the rest of my seedlings to come up?
Click to expand...

Ah...I see now. I personally leave mine on/under until I'm well over 50% germ. Sometimes over 75%, depending on germ rates. I usually eyeball it depending on how the flat is doing overall.

But mid-80s temps aren't going to at all be detrimental to your seedlings. The only downside I can see is that they may grow faster and possibly get a little leggier that way. I had to watch this for my plantings this year, for sure. And, of course, the cells are going to dry out faster with the additional heat, so you'll want to keep tabs on that closely.
 
Thanks EM. Yeah, I was definitely noticing that my cells have been drying up. I can water in the morning and when I come back at night they're pretty much bone dry. I'll be watering a lot more this year to keep up, but that should be relatively easy to manage.
 
WalkingStickMan said:
Thanks EM. Yeah, I was definitely noticing that my cells have been drying up. I can water in the morning and when I come back at night they're pretty much bone dry. I'll be watering a lot more this year to keep up, but that should be relatively easy to manage.
Click to expand...

Np.

Yup. Sounds about right per my experience. I usually mist twice daily. Once in the morning and once before turning in. And that's even after the heat mats are off.
 
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