heat mats- how long do seedlings need heat?

[davespitzer]

Maybe a silly question, but how long should I leave my seedlings on a heat mat? Just until they are up and going, or until they have true leaves, or until they're ready to transplant? I have limited space in my little greenhouse and want to start succession plantings, but there's no room on the heat mat. It's averaging 45-50°F at night, 80+ in the daytime in the greenhouse, probably mid 70's outside during the day (for now- weather's unpredictable this time of year here.) Thanks- Dave

[hill60]

What I've been doing is as they just get true leave I take them off the heat. The heat seems to make them as leggy as stretching for light.

[mdvpc]

I take them off as soon as they germinate.

[Farmette]

I also take mine off just as soon as they germinate and get them under light.

[clamato]

I think their tough little buggers. I move mine to outside and begin hardening them off as soon as they sprout.

[Gobig_or_Gohome_toms]

As soon and they first start coming up take them off the heat.

Craig

[les matzek]

protect them from wind and get them in
direct sun as soon there are starting to
push up the seeding mix, good luck.

les

[davespitzer]

Many thanks- that's exactly what I needed to know. I will move them outside tomorrow morning. Dave

[kpatrick925]

So when you put them outside, are you protecting them from the wind primarily? or the sun? I have my seedlings under light right now but they are almost too tall (getting ready to touch the light) I am not ready to plant them yet but we are having a lot of wind right now. It has been in the low 40s at night and low to mid 60s during the day although it looks like it is supposed to warm up over the weekend. I want to put them out in the sun but am afraid the wind will beat them up. Are they ok with direct sunlight just not direct wind? This is my first time starting from seed and I would hate to kill them all because I didn't know what I am doing. I am including pics as I am very proud of my progress so far.

[clara]

When my seedlings are looking like yours, I put them outside, but for the first days not in direct sunlight and protected from strong wind. Some sunlight in the morning or afternoon and a little bit of wind, yes. clara

[kpatrick925]

Originally Posted by clara

When my seedlings are looking like yours, I put them outside, but for the first days not in direct sunlight and protected from strong wind. Some sunlight in the morning or afternoon and a little bit of wind, yes. clara

Thanks for the response Clara. I will start getting them used to outside but protected from too much sun and wind.

[dice]

[Transition from inside under lights to outside in wind
and sun]

Feldon's guide for hardening off seedlings:
http://www.settfest.com/2010/06/star.../#hardeningoff

Photo showing sunburned tomato leaves (what happens
when they go into the garden with insufficient hardening
off first):
http://2.bp.blogspot.com/_5TlVck4SXN...0/IMG_9671.JPG

[kpatrick925]

Originally Posted by dice

[Transition from inside under lights to outside in wind
and sun]

Feldon's guide for hardening off seedlings:
http://www.settfest.com/2010/06/star.../#hardeningoff

Photo showing sunburned tomato leaves (what happens
when they go into the garden with insufficient hardening
off first):
http://2.bp.blogspot.com/_5TlVck4SXN...0/IMG_9671.JPG

Thanks Dice. I noticed that the plants I bought from the nursery have leaves that are sturdier than the plants I am growing from seed. Does this happen when hardening off or is it just a natural occurance of maturity? There seems to be a lot of info on hardening off but I'm curious of what I'm looking for in my seedlings as I go thru the process. How do I know when they are hardened off and ok to just be out? Great website by the way.

[dice]

Hardening off is mostly a change in the surface cells
of the leaves and in the cells of the stems. It is not something
that you can see without a microscope.

Nursery plants have a few differences. They have more
light when they are growing after first sprouting. They have
nutrition that aids them in growing thick stems and leaves.
The temperature in greenhouses is adjusted to what is best
for the plant at that stage of growth. Some of the plants have
a growth retardant sprayed on, so that they are older than
the height of the plant would indicate.

They may or may not be hardened off. Growers in Florida
have reported sunburn on plants that were sitting outside
under a screen when they were purchased and transpanted
into a garden that got 12 hours of direct sunlight. They were
hardened off against the wind (the stems were thick and sturdy),
but the epidermis had not undergone sufficient hardening
off to withstand all day sun. (Leaves can actually get windburn,
too. People in the North American great plains and southwest
sometimes see it. Symptoms are similar to sunburn.)

[kpatrick925]

Originally Posted by dice

Hardening off is mostly a change in the surface cells
of the leaves and in the cells of the stems. It is not something
that you can see without a microscope.

Nursery plants have a few differences. They have more
light when they are growing after first sprouting. They have
nutrition that aids them in growing thick stems and leaves.
The temperature in greenhouses is adjusted to what is best
for the plant at that stage of growth. Some of the plants have
a growth retardant sprayed on, so that they are older than
the height of the plant would indicate.

They may or may not be hardened off. Growers in Florida
have reported sunburn on plants that were sitting outside
under a screen when they were purchased and transpanted
into a garden that got 12 hours of direct sunlight. They were
hardened off against the wind (the stems were thick and sturdy),
but the epidermis had not undergone sufficient hardening
off to withstand all day sun. (Leaves can actually get windburn,
too. People in the North American great plains and southwest
sometimes see it. Symptoms are similar to sunburn.)

Ah, thanks. There was just such a difference I was curious. My seedlings are so fragile I wasn't sure if something was wrong or if they would get tougher. Appreciate your patience with my questions.