Second layer of plastic and frost cover?

[bower]

Originally Posted by Cole_Robbie

Bower is cheating with all those water buckets!

LOL - just kidding. I do the same thing with horse troughs full of water, or at least am much as I can. I have never seen mass used under benches on a commercial scale. It might be difficult to do in a cost-effective manner. And it's the same with anything that costs more, it might work better on a smaller scale, but not translate well to a larger scale.

Too true about scale.
One thing I always noticed about the use of water containers as solar mass, it can take up one heck of a lot of space. I had these 5 gallon buckets anyway, and the plank was something I had laying around, so the usual "whatever you have handy" approach. But I think it makes a lot of sense for me to use buckets as the under-bench. Insofar as heat rises, any heat trapped or retained by the water is going to be released upward to the seedling bench.

BTW, I have learned it is a bit of a misnomer to think only about "solar" mass. The fact is, any kind of mass will act as a passive heat storage over time. Even mass which is not optimal (or optimally placed) for solar capture will absorb heat and come to temperature in a (solar or otherwise) heated space, which is then released slowly and moderates the temperature.

[Cole_Robbie]

Mass can store cold, too, as well as heat. That's why the mass concept does not mix well with paying for heat. In the morning, when the mass is cool, the heat has to run more than if there was no mass at all.

[FourOaks]

Originally Posted by Cole_Robbie

Mass can store cold, too, as well as heat. That's why the mass concept does not mix well with paying for heat. In the morning, when the mass is cool, the heat has to run more than if there was no mass at all.

That might be where the benefit of a Greenhouse or High Tunnel comes in. The plastic covering assisting with heating the ground beneath it, keeping it warmer, over the long term.

But I agree about the mass of cold causing excess heat expenditure.

[FourOaks]

On a side note, looks likes next weeks forecast is predicting lows in the upper 40s. Might be a good chance to start hardening off.

[FourOaks]

Something occurred to me. In the debate of having the flats on the ground vs up on benches, why not a little of both?

As Carolyn pointed out about Pill Bugs/Sow Bugs, and as Cole pointed out about heat radiating from Earth, maybe the simplest answer is the easiest.



My solution is to have the benches closer to ground level. Just using one level of block gets the benches about 8 inches up off the ground.

A piece of Frost Cover could easily touch the ground, helping to direct the flow of warmth UP into the flats.

I wouldnt call this a "work bench", as its way to low for my preference.. but for flats or baskets that are already seeded, it seems like a winner.

[Rajun Gardener]

Originally Posted by FourOaks

On a side note, looks likes next weeks forecast is predicting lows in the upper 40s. Might be a good chance to start hardening off.

The forecast is looking great for South Louisiana, I think the freezes are gone till late November. I checked 15 day and the lowest was 45. I think I need to start checking ground temps.


As soon as it's dry enough I'm playing in the dirt!!!!!!!

[bower]

Originally Posted by Cole_Robbie

Mass can store cold, too, as well as heat. That's why the mass concept does not mix well with paying for heat. In the morning, when the mass is cool, the heat has to run more than if there was no mass at all.

Cold is just the absence of heat and I guess, the capacity to store it. That depends on the material in question and how readily it is heated and gives off its heat. Small sealed containers of water for example, will rapidly come to equilibrium with the air temperature, compared with stone or earth which warm and cool really slowly. The storage mass in my stone floor in the greenhouse gets deeply heated during the summer months and this continues to moderate temperatures in fall and winter, but our winter is long and so by spring there is little or no stored heat left to warm the air at night. The same goes for the earth in my friend's greenhouse. The surface warms quickly. We wait for the ground to warm deeply enough to plant tomatoes. I have dug planting holes in May only to find the ground really chilly at the bottom of the hole.

Meanwhile the coldness of stone floor or the soil at depth does not affect air temperature afaict, nor how fast the air warms when the sun is shining.
I guess I can't get my head around the idea that it would cost more to heat when using passive storage mass. It makes no sense to me. The heat it absorbs is gratuitous, a bonus on heating the air. I think so? Which reduces the need for heat overall.

[bower]

Originally Posted by FourOaks

Something occurred to me. In the debate of having the flats on the ground vs up on benches, why not a little of both?

As Carolyn pointed out about Pill Bugs/Sow Bugs, and as Cole pointed out about heat radiating from Earth, maybe the simplest answer is the easiest.



My solution is to have the benches closer to ground level. Just using one level of block gets the benches about 8 inches up off the ground.

A piece of Frost Cover could easily touch the ground, helping to direct the flow of warmth UP into the flats.

I wouldnt call this a "work bench", as its way to low for my preference.. but for flats or baskets that are already seeded, it seems like a winner.

This is very similar to our setup at the farm. Works for us!

[FourOaks]

Originally Posted by Rajun Gardener

The forecast is looking great for South Louisiana, I think the freezes are gone till late November. I checked 15 day and the lowest was 45. I think I need to start checking ground temps.


As soon as it's dry enough I'm playing in the dirt!!!!!!!

Good times to be had my friend. I need to do some tilling myself, but with all the rain and high water table, I would be more likely to lose the tiller. Into the muddy abyss never to be seen again.

Originally Posted by bower

This is very similar to our setup at the farm. Works for us!

Good to hear!

I wish I could say this was completely my idea, but it wasnt. Few years back I visited a Family run business, and saw this. In their front/side yard they had 4 Tunnels. Probably 18x50. Each tunnel had 3 rows of benches. Benches were 4 foot wide, and ran most of the length.

The benches either had really short legs or block. I dont remember for sure. But I do remember thinking that they were WAY to low to the ground.

I think I know why now.

One of the great side effects of doing benches this way, less concrete blocks to move around. And I am all for that.

[FourOaks]

So, another interesting observation. Maybe because we are getting closer to spring. The current temp outdoors is 41 Degrees. The temp in the Seedling house is 60 degrees. Impressive because it is rainy and gray outside.

Havent seen the Sunshine in days.

Also, a few pepper plants that didnt get transplanted were accidentally left in there overnight. No heat, not covered, nothing. The overnight low was about 39. The peppers look just fine. Which really shocks me.

This is a good discovery, as earlier I discovered that the Gas Furnace is dead. Might just be a good time to invest in the Frost Cover material.

[Cole_Robbie]

In the spring, I get about 10-15 degrees above the outside on a cloudy day, and up to 50+ above the outside on a sunny day, at least back when I had new plastic. My rating on it is 3-5 years, and I am just starting year 7. So it's not in the best shape, but what I have learned is that a perfect greenhouse is a solar cooker on a sunny day, so a few leaks here and there are mostly insignificant.

[bower]

Yup, even grey days catch some solar heat.
I noticed that pepper plants are hardier than tomatoes. I've seen them unscathed when tomato plants were toast. They are pickier about the temperature range for setting fruit, but the plants themselves are pretty tough.

[FourOaks]

I guess so Bower..

Like I said, it was a pure accident. But sometimes those accidents glean good information. Especially since I need to move more stuff out to the seedling house, to make room under the T8s in the house for more seed starting. Which is tomorrow.