Green house temperture

[bob0923]

My seeds are sprouting and light now applied. What temp do I need to keep in the greenhouse? Would this be for 24/7?

[AKmark]

I keep mine 62-64 at night, and around 78 during the day when possible. I have tried lower temps at night, things don't happen as fast.

[Nematode]

Cardinal temperature is what you seek.
Some info from Canada.

http://www.omafra.gov.on.ca/english/...fo_tomtemp.htm

[psa]

I transplant my seedlings at two weeks from sowing into a cool greenhouse with 40F nights and 70F days, and then at four weeks increase to 50F nights and 80F days, before hardening off at six to eight weeks. The cooler temperatures give me better root development and stockier stems, plus easier acclimatization to outdoor growing. A good fan or other mechanical disturbance makes a big difference in the greenhouse as well (thigmomorphogenesis).

Growth is fastest at 80-90F, but the resulting plants are very weak, even when constantly ruffled with fans.

[sjamesNorway]

The article about thigmomorphogenesis is interesting. I've always used a fan on my seedlings, but it looks like we should be nudging our growing plants in the greenhouse.

Steve

[AKmark]

Growth is fastest at 80-90F, but the resulting plants are very weak, even when constantly ruffled with fans.[/QUOTE]

Maybe our areas are different.

[psa]

Again, I was talking seedlings to be planted outdoors. Once ready for production growth, higher temperatures are advantageous, and greenhouse plants are subject to different stressors that outdoor plants.

[Cole_Robbie]

I abuse my seedlings as much as possible. Last year, I did lose quite a few early ones from letting them get down into the high to mid 30s at night. They didn't freeze, but the plants turned yellow and quit growing. I think I must have killed off the beneficial bacteria in the media. This year, I am going to move my minimum temp up to at least 50 and see if I still lose any.

My day time temps are very high, too. Heat doesn't really kill plants; they die from transpiring all their water too quickly and drying out, which obviously is exacerbated by high temps. But as long as they don't dry out, seedlings can live through very hot days.

[AKmark]

For those who are growing for greenhouse production, or want high yields, I highly suggest this affordable manual put out by Hydro- Gardens, it is full of very valuable info.

[Nematode]

Below 50f in the root zone is no bueno for tomato.
They go yellow and will kill them eventually, BTDT.
If you are running cold air make sure the roots have heat.

[psa]

AKmark: I sure can't argue with your results.

Originally Posted by psa

Again, I was talking seedlings to be planted outdoors. Once ready for production growth, higher temperatures are advantageous, and greenhouse plants are subject to different stressors that outdoor plants.

I'm pretty sure there are some sunlight differences between Alaska and Washington. That might have something to do with the plant strength.

[Jimbotomateo]

Originally Posted by AKmark

I keep mine 62-64 at night, and around 78 during the day when possible. I have tried lower temps at night, things don't happen as fast.

AKmark, do your long daylight hours present any special problems? . Jimbo

[AKmark]

Originally Posted by Jimbotomateo

AKmark, do your long daylight hours present any special problems? . Jimbo

The long daylight can pose some problems when it is hot outside, but can be a blessing too, if you can keep up on watering, the plants are getting fed often. Our greatest challenge in AK is cool nights, even in mid summer, almost always below 60 degrees.
If a person corrects the environment a little, it can be very rewarding though. We can also get very wet misty summers, these pose a serious problem, disease, and slow fruit ripening. Not much we can do about that.

I grew in a 12x16 GH for 20 years, some varieties did very good, many did not. When I got larger GH's and corrected my environment, I had much better results, much better.

I do understand that there are many methods that work for growing tomatoes, but those methods are fewer in number when it comes to commercial production. In other words, most of the trials have already been done, experts backed by science tell us exactly what to do. I have had the best luck following their programs, not trying to create my own. They base their science on leaf analysis, at any given time during the grow and it is a perfect method. It is not an AK thing, or a US thing, it works everywhere, if the environment is favorable, and we can spruce it up in a GH if need be. Subtle differences do occur from area to area, I seem to need a bit more MgSO4, it helps keep my large leaves green and healthy looking. The old timers used to call Mg deficiency length of day syndrome up here, all they needed was a bit more Epsom salt. LOL

I like to start with healthy seedlings, but spindly ones work fine, they do have a recovery time though before they kick into high grow rate.
Like I stated above, if your a GH grower buy that manual, it is full of info and is maybe 10 bucks. HG is huge, they sell to thousands of production growers.

Here's a pic of my first batch of seedlings for this year, I was happy with them, now they are all planted in the GH.

Originally Posted by AKmark

Like I stated above, if your a GH grower buy that manual, it is full of info and is maybe 10 bucks. HG is huge, they sell to thousands of production growers.

Here's a link to the product page for the store that sells the manual. Thanks for the tip.