Red Plastic vs Black Plastic

[roerinaci]

Good Morning..I'm up in Northern New Hampshire and was wondering if using Red Plastic would benefit my tomato plants come this spring Or should I just use the black plastic..I've never used either curious if this would give my tomatoes a boost ..

[Cole_Robbie]

Black would be better for warming the soil in the early spring. After that, red does work the best for flowering crops like tomatoes, but the difference is not huge. I don't use red, because the black is so much cheaper for the big rolls.

[roerinaci]

Cole Thank You ..Should I get a certain kind of black plastic ??

[AKmark]

Look for IRT, it is very popular in Alaska for gardeners and farmers.

[roerinaci]

Ok Thank You AK

[carolyn137]

I was at a NE Vegetable Conference in Sturbridge, MA many years ago when Clemson U first introduced the red plastic. It was designed for commercial farmers who grew compact varieties since there has to be a certain distance of it on each side of the plants.

They estimated a 20% increase in yield, that's what it's all about, not increasing soil warmth, but it became clear after a few years that it was closer to maybe 10%.

Take a variety that normally gives 50 fruit, add maybe 5 more for the effect of the red plastic then add on the cost of it and IMO it makes no sense.

For commercial farmers with hundreds of acres maybe,

Carolyn

[PaddyMc]

I'll second the IRT, the stuff is amazing in cold climates.
I specifically use IRT 100 (Harris Seeds is a good source). I grow everything on the stuff w/soaker hose underneith. The keys to making it really effective are to make broad rows running east-west ( so there's an extra warm "south side") and to get the plastic really tight to the soil.
The way I do that with tomatoes and peppers is to do "sets" of two rows together, with a total width for the two rows of about 3'. Then I lay the IRT over the two rows (it comes in 4' wide rolls). Then I carefully shovel soil on about 6" of edge on one side all the way down the row. Then I do the same on the other side, but I do it in about 5' sections and pull the edge of the plastic to stretch it over the rows.
Finally, I go back and carefully shovel a small amount of soil onto the top of the plastic between the rows. The weight of that soil stretches down the plastic, so you have distinct rows.
I do all of that about 3 weeks before I want to plant, and run the water for about 30 minutes every 5 days or so leading up to my plant out date. This ensures some nice warm, moist, soil when you plant. To plant out, I cut an "X" in the plastic (small, cheap, "mustache trimmer" scissors work great), and dig the hole. I also try to alternate which side of the plants the hose is running on, which helps ensure even watering for the whole row.
Extra tips --
Really test and check your soaker hose or drip system BEFORE you plastic over it.
White or Silver perminant marker (Sharpie) works awesome as plant labeling right on the plastic, as long as you do it while the plastic's still dry and clean (ie before you dig the hole).

Some pictures --



Newly planted, IRT-plastic rows.



A little braggy, but here's 550 lbs of ripe watermelons I grew in two rows in my front yard. Zone 4b!
All on IRT mulch (never grew a single one to fully ripe pre-IRT).

[AKmark]

You just saved me the time of pulling out pics too, some may not agree, but I assume they have never used it. It is amazing stuff, I have used it for 20 years, and used to grow up to 70lb cabbages with the stuff. My friend who commercially farms, also puts clear plastic, over small hoops, on top of IRT for zucchini, he is king zuc in all of AK

[Salsacharley]

What do you do with the plastic once the weather gets hot?

[biscgolf]

By the time the weather gets hot your plants have theoretically grown enough that they prevent a lot of the sun from reaching the plastic and thereby heating it too much. For summer plantings of cooler weather crops we switch to white plastic to keep the root systems cooler.

[PaddyMc]

Originally Posted by biscgolf

By the time the weather gets hot your plants have theoretically grown enough that they prevent a lot of the sun from reaching the plastic and thereby heating it too much. For summer plantings of cooler weather crops we switch to white plastic to keep the root systems cooler.

This. If I lived somewhere hot enough for that to be a problem, I wouldn't use it.

[surf4grrl]

I have stopped using plastic on tomatoes and they do fine without it. The roots will go deep anyway, and that soil is not warmed by the plastic that deep. I sill use plastic for eggplants, okra, peppers, and sweet potatoes. I think we did pretty well sweet potato wise - over 10 600' rows, the farm was able to harvest over 10,000#. Not bad. You have to be able to manage the weeds in between the plastic though; mechanical cultivation won't work and will rip up the plastic.

[ddsack]

Your crops look great, PaddyMc !!!
I'll be looking into it for next spring. I had to go searching for what IRT stands for since none of the selling sites I checked had it spelled out. Found this interesting article -
http://growingtaste.com/mulches.shtml where I finally saw that it stands for "Infra-Red Transmitting."

[PaddyMc]

Originally Posted by ddsack

Your crops look great, PaddyMc !!!
I'll be looking into it for next spring. I had to go searching for what IRT stands for since none of the selling sites I checked had it spelled out. Found this interesting article -
http://growingtaste.com/mulches.shtml where I finally saw that it stands for "Infra-Red Transmitting."

Yeah, I should have said that. That's the difference from standard black plastic. IRT 75 lets in 75% of infra red light. IRT 100 lets it all in (while pretty much blocking the visible spectrum.

As to Surf4grrl's point about weeding, plastic mulch has pretty much eliminated weeding for me. In between my rows, my foot traffic keeps most of the weeds down, and the rest, I just ignore. Also, though I agree that plastic mulch warms the soil most in the top 6-8", I think one of it's most important benefits for cold climates isn't just the warm soil itself, but that warmed thermal mass radiating overnight, which helps growth rate, and gives a couple extra degrees of frost protection (this spring, I survived two nights of 31 degrees and one of 30), while my neighbors non-plasticed plants got nuked. All of that only really makes a big difference in short-season, cold climates, but it adds up.

[carolyn137]

First, your reference to Harris Seeds and IRT.

I LOVE Harris seeds and have since I was a kid and what we called the Harris man came to the house to discuss with my father what was new and take his order. This was back in the 50's. They are based in Rochester, NY and when I was in grad school there I went to their demo fields a couple of times. Their seeds have always done well for me and it's where I got my Permanest trays and labels and so much more.

There was a bump in the road when they merged with Moran Seed but evetually the Harris folks bought back Harris.

Now what I really wanted to say.

Watermelon, I love it. I used to grow lots of them before I fell and got into this walker permanenly, but more to the point, if your IRT is that great you owe it to yourself to send me a few when close to being ripe and I pay postage. The alternative is you driving cross country to deliver, I put you up at where I did same for Craig LeHoullier and his wife and pay for your meals since I don't cook at all anymore. I was just taught how to use my Microwave.

My father spoke of plugging watermelons to see if they were ripe. Does anyone do that these days?

Carolyn