Read the growing seedlings info on my website and several of your questions will be answered. As for when to move seedlings into the greenhouse, that depends on your light setup, growing conditions, and temperature in the greenhouse. If you are unsure, try moving some of the seedlings to the greenhouse for a week and see how they adapt. Also, don't forget that moving from indoors to a greenhouse requires hardening the seedlings off. Direct sunlight is still direct sunlight even in a greenhouse.

growing seedlings

Thank you. The link was very helpful!

Agree that in your zone when you can move them to your GH all depends on if your GH will be heated or not. Tomato plant seedlings will require supplemental heat to maintain the GH temps above 50 degrees. Your zone will have many nights well below that temp.

You will also have to insure that the temp during the day never rises above 80 degrees (max) during the sunny days - that requires close monitoring. Maintaining 65-70 is better. Even on a sunny day in mid-winter temps inside a GH can easily rise to 100 degrees of more.

In addition to Fusion's website also check out the FAQs over on the Growing from Seed forum here and do some reading on the Greenhouses forum here too for how-to-use-GH tips.

New GH owners have lots to learn first if you want to avoid many of the common mistakes made. :)

Dave

The greenhouse will be heated. I am trying to find out what the nighttime temp should be. I need to have a plant I can sell at a plant sale for charity starting May 1st.. So I planned on starting them inside under the lights about the last week of Feb with the Idea of getting them in the GH by St Patrick day.
I have cross posted this question in a few forums including the GH one. my husband is at home during the day it will be his job to monitor the day time temps.
I am trying hard to avoid the newbie mistakes.

I am trying to find out what the nighttime temp should be.

As fusion and I said above 50 degrees, no lower than 45. The ideal growing temp range is no lower than 45, no higher than 70. Not always possible but its the ideal range.

Dave

You have more flexability than mentioned on those sites in temps but be advised that plant growth is compromised as you allow temps to stray. The absolute minimum is actually below 32*F if plants are hardened off.

What I'd suggest you do is incorporate thermostatically controlled louver(s) and exhaust fan(s) and also circulation fan(s) to avoid temp extremes b/c they will occur even when you think someone is watching.

If you do move plants into the greenhouse in mid-March hardening is much less of an issue as the sun is lower in the sky. I have almost ignored it over past 10 years for those earlier plantings.

Can you plant out May 1 in your zone? I figure on Mother's Day to Memorial Day here. Your customers might need to do some hardening/hold off on planting a week or 2 after the sale.

If your GH is being built now, I'd monitor the temps and try starting the seeds (on heat mats) right in the GH in Feb, then depending on the weather move them outdoors for hardening or just vent the GH more the end of April to try to get them used to "outdoor" temps (assuming people are going to plant these outdoors) before the sale. But let people know what temps they've been exposed to, and keep an eye on forecast, they might need a little more hardening before planting out.

So you intend to sell seedlings by May 1st ?
This tells me you will have to start from seeds NO EARLIER than March 15. This way you will have some right size plants, not too small , not too lanky.

Tomato seedling need 12 to 16 hours of proper light.
As already mentioned , ideal temperature is 65F-70F. Anything lower than 55F, you will get purple color on leaves and stems INDICATING that they are not able to uptake enough Phosphorus and probably not enough Calcium and other elements.

With green house, starting March 15th, you shouldn't have a big heating and light problem, even in your zone. BUT you need to have an automatic control system to : (1) prevent possible over heating and (2) night time backup heating system, to kick in when it gets , say below 47F.

So by using my fingers I figure out that you have 4 months to think about it .

Good Luck !

Seysonn

I'd say end of Feb - Mar 1 b/c people tend to want bigger plants at plant sales, not the little seedlings we're used to transplanting. And I don't know if starting them in a GH that could be (hopefully) a little cooler than a house would make them grow a little more slowly. You don't want to keep them in an 80 degree GH and then try to harden them off to plant outside, but you don't really want to move them from house into GH and then outside b/c that means hardening off twice. That's why I suggested starting them in the GH (that maybe would be 70 or so during day and over 50 at night?).

Growing in a greenhouse where the temperatures are allowed to fluctuate down to 50 and up to 100 on a sunny day slows growth down quite a bit. I start seedlings between the 25th of February and March 15th for that particular market. In other words, you need 6 to 8 weeks to grow full size plants for May 1st sales.

Also, I suggest growing in 4 inch cups which is a much more marketable plant than smaller cells.

There is nothing wrong with your timetable of starting plants the end of Feb. and you probably already have reasoned that a 4" pot just won't cut it for the type of plant you are thinking about by May 1st. Order your potting mix soon and plan on Gal. pots. Those larger plants have always been good sellers for both the deck gardening and early starting gardeners. Even better if you have a few ripe tomatoes dangling from the plants.

what kind of greenhouse are you building?

Thanks for all the input

So ...if I kept the night time temp around 50 could I start seeds right in the GH?

The greenhouse has auto vent openers. DH will be home to open door if needed.

i run the plant sale every Fri,Sat and Sun in May to benefit Children Hospital in Boston. In the 5 years I have done it I have found that Tomatoes that you can't get at places like HD,Basil,and Hot peppers are a big draw. So

You can germinate seeds in a cool greenhouse AS LONG AS THE SEED FLATS ARE HEATED. Heat mats or buried heating cables will be needed to heat the soil. Once germination has occurred, the heat source must be turned off.

I have (it's all put together now ..just need the heating cooling put in!) this one Elite Greenhouse - 11'8'W x 8'10'H x 16'6'L
with the recommended heating and accessory package

Our Medium Greenhouse Equipment Kit is the perfect add on to any of our 100-200 square foot greenhouses. We have packaged some of our best greenhouse accessories into this economical kit. Recommended for the following units: 103993, 104564, 104605, & 104609.

Kit Includes:
⢠10,000 BTU Heatstar Blue Flame Greenhouse Propane Heater.
⢠2 NEMA 4 DuroStat Dual Voltage, Waterproof Thermostats.
⢠50' 5/8' Coil Hose.
⢠Telescoping Watering Wand.
⢠Heavy-Duty Pistol Grip Sprayer.
⢠12' ValuTek Hanging Circulation Fan.
⢠12' ValuTek Direct Drive Exhaust Fan with Shutter.
⢠12' ValuTek Motorized Heavy-Duty Aluminum Intake Shutter.

Here is a link that might be useful: Farmteck greenhouse

I have (it's all put together now ..just need the heating cooling put in!) this one Elite Greenhouse - 11'8'W x 8'10'H x 16'6'L
with the recommended heating and accessory package

Our Medium Greenhouse Equipment Kit is the perfect add on to any of our 100-200 square foot greenhouses. We have packaged some of our best greenhouse accessories into this economical kit. Recommended for the following units: 103993, 104564, 104605, & 104609.

Kit Includes:
⢠10,000 BTU Heatstar Blue Flame Greenhouse Propane Heater.
⢠2 NEMA 4 DuroStat Dual Voltage, Waterproof Thermostats.
⢠50' 5/8' Coil Hose.
⢠Telescoping Watering Wand.
⢠Heavy-Duty Pistol Grip Sprayer.
⢠12' ValuTek Hanging Circulation Fan.
⢠12' ValuTek Direct Drive Exhaust Fan with Shutter.
⢠12' ValuTek Motorized Heavy-Duty Aluminum Intake Shutter.

Here is a link that might be useful: Farmteck greenhouse

What a nice greenhouse. Enjoy. (I have nothing to offer on how to grow in one, though). Children's hospital is lucky to have someone as dedicated as you raising funds for them.

Caryl

I'm in SE MA as well and I think with your set up you can definitely get them in that house fine. I mean with hoop houses I've made I'm setting them in the ground April 1st or so. I have to take internal precautions like covering them with fabric like weed guard but they live. You've got an engineered structure with heat. I think your plants will do fine. Light is a factor as others have said. Those Bonnie types you see are grown in Alabama I think. Their greenhouses are warm but they also probably have hot lamps above them. Don't for get fans and rotating the plants to make them strong. Don't know if this would be too expensive or impracticable but you really want nice looking plants use fabric pots. By impracticable I mean transplanting or the cost and weight of a final destination(I'd go with 30 gallons if I was planting at home). It's amazing the way the plants just get all bushy and healthy thanks to the self pruning going on below. Another consideration is to maybe sell the fabric pots with the tomatoes and even have a sample on hand to demonstrate(meaning you start a plant now and transplant it into a decent size fabric pot(10-20 gallons)for the wow factor).