black tarp/heating ground

[joed2323]

Not sure what section I should have posted this in, sorry if its in the wrong section.

I know some people put down black tarp material to heat up the garden to get temps up quicker.
I'm thinking I may try this for this year depending on when we can get the snow to finally say goodbye around here, its almost gone...

Is this a waste of time, or does this actually work? How long does one need to leave the tarp on for, I'm sure there is lots a factors... thanks guys

[Dillbert]

a black opaque tarp is a poor choice.

use a clear polythene sheet - the solar energy passes through the clear sheet and heats the ground orders of magnitude faster than if covered by "black"

[joed2323]

OK if its clear then why does covering it make a difference. Is it the clear tarp traps in heat that is transferred through the clear plastic??

You guys are great! Thanks again

[Northernfox]

Won't it trap the moisture?

[Dillbert]

clear allows the solar energy through, and traps the heat.
same as with a greenhouse - if greenhouses had black glass, they wouldn't get all to hot....

opaque does not let light/energy through, color black gets hot but then has to "transfer" the heat to the air, then from the air to the soil.

yes, it will also trap moisture - you'll see that as condensation on the bottom of the plastic. the trapped moisture it is not a problem.

[joed2323]

Dillbert would you/have you done this
So it should work good for my situation being in north Michigan

[Dillbert]

have done
do regular

I have a roll of 36 inch wide poly - put it down over areas / rows where I want the soil to warm up more quickly for direct seeding.

our last frost 'safe' date is mid-May - but I can move up direct seeding a full month by pre-heating the soil. bear in mind, if you get a frost snap, you have to be prepared to cover aka 'protect' the tender sprouts. not a lot of sense in speeding up the season only to have all the sprouted stuff kilt-daid by a late frost.

[joed2323]

Wow dillbert, thats incredible that you can move up the planting date by almost one month

Is this some special clear plastic tarp that I can only buy somewhere special??
Would any clear plastic do the job or no??

thanks for your advice so far

[Dillbert]

don't go ueberbord.

"moving up" - yo, it's not an absolute term.
odds are you can put clear plastic down. it may move up the soil temp 20-30p'F from "normal. "

sokay, soil temp is "up" - this is of absolute zero consequence when the air / weather temps drops to 32'F, or less . . .

so ref "moving up the planting date a month"
yes, but only if "the weather" cooperates,
averages are exactly that - long term guidelines - not a real life factor to today's weather forecast.

if yuo have possession of a weather forecast who has a better than "toss the dice average" - in terms of accuracy - show the dude; no one else else isd anything close..

[ReptileAddiction]

If you do it correctly I have witnessed it getting over 120-130 in there when it is only like 80 out.

[joed2323]

Please help me Another snowstorm heading for me, 4-8 inches coming.. I just started to see the grass and dirt in my garden finally and now this again!! Mother nature does not like northern Michigan this year

I'm gonna need all the help and ammo I can get after this little storm. This is a crazy spring.

I'm going to shovel my garden this time believe me or not, although it could probably use the water from the snow melt..
Temps will be back up after Friday

[Fourspot]

I'm interested in doing this too. Trying to warm up the soil to grow some melons. Has anyone used black trash bags? I'm trying to use what I have on hand for a couple of honey dews. My seedlings didn't make it in the garden last year. I probably planted it too early during mid May.

[Northernfox]

I hope to start mine the first week of may. Ill have to build little greenhouses for them to get the germination temp and keep the soil warm should be interesting to see how it works

[veggiedan]

I agree that clear plastic is much better than black plastic for warming your soil. It's pretty basic physics, and yes, it's exactly like a greenhouse.

Black plastic will absorb sunlight. The PLASTIC will get warm. Not necessarily the ground underneath. Because that warm plastic is trying to warm both the air on top of the plastic and the ground underneath, you lose half the heat to the air.

Clear plastic will let the sunlight hit the ground *and* keep the cold air from cooling the ground off off when the ground warms up. The heat from the sunlight is all asborbed by the ground, and stays mostly under the plastic. Think TRANSPARENT INSULATOR. That's what you want. The more transparent the better, and the more insulation the better.

Glass is better than thin rollable plastic. Why? Because it's at least as transparent, and is a somewhat better insulator. But you aren't going to cover your ground with glass, unless it's a greenhouse.