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I don't really have a space in my house that I can dedicate to seed starting, so I'm wondering if I can do it in my shed.

I'm going to be starting things like broccoli and cabbage in January and February, so obviously it's going to be cold out. Will the heat mats keep the soil warm enough? There is no way my boyfriend will let me put a space heater out there unattended, so the mats would be the only heat source.

If that won't work, I guess I'll have to figure something else out, but the shed would be my first choice.

What about lights?

Also, does the shed have windows to let in sunlight to help warm the interior? Can you add skylights?

Haha, I keep thinking of something else -- based on my experience with my unheated garage, broccoli and cabbage will sprout better in the 70's and only take 2-3 days at 75-80°F. If you can keep them warm -- 50's-60's daytime temps they can take/(grow in) colder temps. Cold weather crops will grow but slowly if you can keep temps in 40's or above.

I was planning to get those big shop lights. The 2x4' or so fluorescent deals. Am I correct in understanding that fluorescent lights don't produce much heat?

There is one small window, but it's facing west and into trees. Not much light to speak of there.

Skylights COULD be done, but again there would be trees shading it and it's really just not in the budget at the moment. Maybe in a year or two.

High-low averages here for January and February are 42-25 and 46-27, respectively.

You are right that the fluorescent lights don't give off much heat. That is what you need for starting seeds, so that you can get the seedlings right close to the light without burning them. Having a couple incandescent lights somewhere else near the plants, but not right next to them, might help keep the temp up a bit without the safety issues of a space heater (though personally I think the ceramic heaters are quite safe and I would use one). Besides safety though, a space heater is a big power drain. I already worry about how much power my seed starting operation uses with all the lights and two heat mats.

Anyway, a couple regular bulbs might help in a small enclosed space - especially if the space is insulated. And you are right, as long as they are not freezing, the soil temp is most important. As long as you can keep the soil well warmed up, the cold air will slow them down a bit, but not stop them. And they will be better adapted when you put them out. Be sure you get them off the heat mats once they are well started, so they aren't too coddled.

Good idea to think ahead on seed starting. Next question is how many plants do you anticipate needing? There's a big difference between 12 and 36 broccolis when thinking seed start and then garden space. I can give you some tips on how one might do smaller amounts. But not for a few days, after long wkd.

My current sketches include 9 broccoli and either 3 or 6 cabbage. I will also have onions going in at the same time, but I'm not sure if I'm going to start them first or directly sow them.


The shed isn't currently insulated, but it's on my list of things to look in to. We are emptying it out tomorrow, cleaning, putting in mold-resistant paint... and finding out how the squirrels are getting in.

In NH I had access to an unheated greenhouse. A drop light (with a 60W bulb) did a pretty good job to under heat a few flats that were tented with plastic.

Later, at another NH residence a kerosene lantern at night warmed a cold frame with a tarp over the glass.

So it depends at least and much where (and the volume heated) the heat originates as the amount of heat supplied.

You will probably want those shop lights too.

Back to this thread! For a few broccoli and cabbage, the expense and work of reworking part of the shed may not justify the end. If you have a shelf or table near a window, and add some extra lighting, perhaps would work for this 1st year. Keep in mind, broccoli and cabbage starts are about $3.50 for a 9 cell pack at the box stores!

I have an area on a kitchen table with good east windows. I put up a couple of shop lights with 40 watt bulbs for heat and light, and recently added a 6" fan to turn on and off during the day. I use the 10-12 seed pellet trays, and perhaps one of the few here successful with the system. I like the coir better than the peat pellets. There are at least 4 trays going at any given time, and this allows for smaller numbers of more variety. At the moment coneflower (TN native), comfrey, chives and lavender, plus some 4" pots of garlic chives. Some doing better than others! Once they get up with true leaves, usually go outside in a sheltered area until big enough to up pot.

Hope this helps more than discourages.