Has anyone ever grown seedling in a cold garage?


Garden Master
Dec 13, 2007
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border, ID/WA(!)
This is from the University of Nebraska:


I hope that chart is a clear enough. What it shows is optimal germination temperatures. I can have real problems with a good number of seedlings together that are germinating at different rates. That leads to crowding of late seedlings by those that are first off the blocks ..... Notice how optimal temperatures for what we usually want as transplants are often warmer than usual home temperatures. Germination can likely be improved by starting the plants in a warmer location than where you are thinking of growing them to transplant size.

(It's been quite awhile since 'Bill has been around and I hope he comes back to tell us if he ever grew those Maruba Santoh greens he was thinking about several years ago ;).)



Chillin' In The Garden
May 2, 2012
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Willamette Valley, Oregon
In the past we haven't been able to grow tomato, eggplant, pepper starts to a size that is suitable to flourish in our climate. Even a south facing window here gets a lot of 'not much' until it's way too late. Lettuce and other fast growing crops are fine.

I bought some foam board at Home Depot today along with some other supplies I'm going to need. Painting it white will definitely be on my list, a small heater with separate in-line thermostat too.


Garden Addicted
Nov 23, 2014
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Hi there 'Bill !

This is a super question for @SprigOfTheLivingDead who grows plants in his basement through the winter.

I have only a very little experience with supplemental lighting. I believe that this is what @catjac1975 does each and every winter. (Others start transplants under lights. You might think that after a lot of growing seasons, I would have experience with that but I tend to gravitate to South Windows and Exposures, instead.)

I did a little driving South(west), recently. Enjoyed being in Portland for Christmas. It has been a long time but I used to be down there, at least, a couple times each year.

Sorry, totally missed this call-out.

I have a 2x4 closet in my attached, uninsulated garage I'd like to use as a mini greenhouse to get some plants started that aren't available locally. I'm thinking of tomatoes, peppers and eggplant varieties that we have grown in the past but have been pushed aside for younger sexier varieties.

I live in the Willamette Valley Oregon, pretty mild 30-50 degrees usually in the winter but can occasionally get much colder. The garage is usually a little warmer but not much.

I'm thinking of using some light insulation covered with cast off mineral based ceiling board. I'm going to buy a grow light and maybe line the space with foil to reflect light all around.

My big questions are heating, ventilation, how far the light should be from the plants at various stages of growth. I think the primary users of this stuff is pot growers but that's not me. If anyone has any knowledge of this that they can pass along I'd appreciate it.

Thanks, Bill
Yes, I grow lettuce, tomatoes and peppers in my basement. However, I do that in a GGT 5x5. Inside that I have a 1000w Hortilux Metal Halide bulb inside a light hood that is air cooled with an inline canfan and hooked up to a charcoal filter, also inline.

first indoor.jpg

That was a good learning experience. I surrounded the metal frame with mylar (reflective bubble wrap) and then hung some T4 bulbs rated for at least over the daylight color spectrum (3500k?). This did great for that year. We got some produce and it allowed me to experiment growing

I'd say my game changer was a flood table and a seedling bay, which has also evolved over time to a seedling closet :)

flood table:
flood table.jpg

Seedling Bay v1:

Seedling Closet (2020):
Plans for this spring are to put lights on the top and bottom shelves as well. Top and middle will be for normal seedlings while the bottom will be for my tree saplings (I own a tree farm)

So, your question about heat... ugh. Some plants just won't respond well without proper temps. If you're growing peppers they're not going to be happy with cold temps. Are you looking to grow to maturity or just for getting a jump on sprint planting? The heat is really supplied by the light, but will generally equal out with the surrounding environment. Got a cold garage? It's going to be a cold tent.

In a seedling stage you'll want them to be really close, but as they get older you can probably pull it away a little. HOWEVER, there are calculations based on the energy of the bulb that will show max distance for plants still getting proper photo-yumyums. Ventilation: just put some small fans in there. I've seen people use CPU fans as they get started and experiment. Once you get going you'll invest more and see what works best for you

get the book Gardening Indoors With Soil & Hydroponics. There's a ton of great information in there to learn.

Current tent:
I would like to flip this out for a 4x9 at some point.
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