http://forums2.gardenweb.com/discussions/1570898/beginners-questions-regarding-heat-mat

I found that I was losing heat from the mat to the underlying surface, table top. Now I place a piece of fabric (an old placemat for example) under the mat and more heat goes UP to the seed tray. Maybe that's all you need to do.

Many discussions about this over on the Growing from Seed forum here (as well as all the FAQs like the one Lucille linked).

Most heat mats will only increase soil temp 7-10 degrees unless you also buy the thermostat to control them. The thermostat will drive the temps higher.

You are losing most of the heat to the surrounding air in the garage. That is how radiant heat works. So you need to enclose, to confine, the small seed starting area in some fashion - many use just some plastic around the shelf or a blanket wall of some kind to help contain the heat to that area.

And if you are using a dome and the water builds up on it then it either need to have the excess humidity drained out periodically or it needs to be propped open slightly to allow for some air circulation or everything rots.

Dave

http://forums2.gardenweb.com/forums/seed

I started using a heat mat with the thermostat set at 75F last year to help get my peppers and spinach going. It worked well. I also used some cardboard under the planter tray to provide some insulation between the table and the planter tray. a couple of pencils between the dome and tray worked for me for ventilation in the beginning but once they sprouted I removed both the dome and the mat, don't wait for everything to sprout. I found that once you see a couple basically the process has started in the other seeds so you no longer need it.

If you can, you might throw a tarp/blanket over your light sources. I do that, with 60W fixtures, and I keep my seedlings at 80F in a 55F garage. No heating mat needed. Adjust the tarp and blanket to get the temperature right. As the garage warms, I throw off some of the insulation to regulate the temperature.

Seems to me that if you touch the mat and you can barely feel any heat coming out of it, that's your problem right there.

My heat mat never feels very warm. It has no thermostat. It will raise the soil temp. about 10 degrees. I don't know about the air temp and basically don't concern myself with that when starting seedlings. But it is in my house and the room is usually around 60 degree...not sure it is any warmer near the seed tray. Setting the mat on styrofoam or another insulating material, even cardboard or a fluffy towel, will help keep more of the warmth going to the seed tray. Keeping a dome cover or plastic over the seed tray helps cut down some on evaporation which cools the soil, also. Once sprouts start to emerge from the soil it is best to remove the cover, though. It has helped a lot with pepper germination for me. I also like it for tomatoes. When I have more trays than there is space for on the mat, I'll set the tray on top of a shelf over the light ballast. That area is warmer and helps heat the soil a little, also. Of course once things sprout I need to move them and get them UNDER the lights :)

Thanks everyone for the feedback. Indonesia have a heat map thermostat as well. I set.it to 75 but it wasn't getting anywhere close to that. I will try to insulate as best I can.

As for humidity, my dome cover has three different vents. I can use those to help maintain air flow. I do not have any seeds in there right now.somihave all the vents closed to see how hot I could get the dome.

I might buy another mat at Lowe's to see if it works better. I can always return it if not.

What is an ideal temperature for trying to germinate various types of seeds at once? I want to start tomatoes, cucumbers, squash, herbs, ECT. I read at mother earth news a good range is 50 to 60 but that seems a little low.

I just did 75 degrees for everything and it worked.

You can soil temp germination charts all over the web but different crops do best with different temps, some extremely different. As long as you are in the range recommended they will do fine. Not to mention that all of those things on your list normally wouldn't be started at the same time.

http://www.gardeners.com/how-to/when-is-it-warm-enough-to-plant/9029.html

Dave

Be careful about plant-out timing. The standard plant-out time is 4-6 weeks after seeding, BUT that's for room temp. I kept mine this year at 80F. The plants went absolutely gangbusters, and were aching to go out in three weeks. The warmer the faster, up to maybe 90F. "Optimal" germination temperatures are about 80F, except for spinach and parsnips and maybe onions, which I think like it colder.

60F is fine, but they'll grow slowly.

Be careful. Many places give optimum germination temps for direct seeding, and those temperatures are always lower. Why? Because after the last date of frost, you're unlikely to have 80F soil! Not gonna be optimal to wait until August to direct seed.

Dave,

All except the squash should be started now in seed trays according to the Gardenate app I am using. I will hold off on those.

Well needless to say there are different climates in zone 7 but it is a good month too early here for me to start tomatoes and cukes and a good 6 weeks before starting any squash. Good luck.

Dave

Hi Dave, yes I am in the Seattle area. Some places tell me this is zone 7 and some tell me it's zone 8b. It.ia very confusing to me. The app I am using takes my zip code and calculates my zone and tells me what to plant in the garden, in seed trays ,and when. to transplant. Hopefully it is right.

I'd take those USDA garden zones with a big grain of salt. Those garden zones specify simply how cold it gets in the winter. That may or may not be pertinent to decisions about date of last frost. To wit, I'm in USDA zone 8a - central Texas, and my tomatoes are out in the ground. But spring gardening is quite different in Seattle (I used to live in the PNW). One would like to believe an app would be able to do it right.

When I look it up, I see that Seattle frost "safe dates" are mid-April. So I agree that it's a month-ish early to be seeding frost-intolerant plants. If the seedlings are kept cool, like the 60F you're seeing, they'll grow slowly, however, and you might be able to start them soon.

Get a lazer hand held thermometer and you can be sure of the temp

Insulate under and over but I doubt you will get it to what you want. I suggest a light bulb "inside" to help heat - but that might be tough to control temps.