Yet another ?, this one on plastic

[Plaz]

What is the purpose of putting plastic on top of tomato containers. I've read where the earth boxes come with it and the GS boxes (if bought with a kit) do as well. I bought only the GS boxes and wonder if I need to add plastic? Or add mulch? Or a combo of both. I started putting plastic on them but it was such a pain in the butt that I decided against it.

Thanks!

[pooklette]

I *think* the plastic's main purpose is to conserve soil moisture. I suppose it would also increase the soil temperature too, which is helpful in some climate zones and harmful in others I assume.

You're using self-watering containers, right? If you leave the plastic off, I suspect you might just have to fill up the water 'chamber' at the bottom a little more frequently.

[Suze]

Here's some reasons I can think of:

1 - Keeping fertilizer strip intact. When folks do a self-watering container setup, there's generally a fertilizer strip put on the soil surface. If the top is left off, rains could water that down into the soil at a faster rate than it should be released.

2 - Evaporation. I read once that up to 80% of the moisture loss in a container can occur due to evaporation under the right conditions (hot and sunny) by not mulching. I don't really grow in self-watering containers, but I have extensively gardened in containers in the past. Mulching made a world of difference in reducing watering requirements.

3 - Disease. Part of the beauty of self-watering containers is that enclosed environment. There's little/no splashback of the potting mixture onto the foliage.

[Plaz]

So if I just put down some mulch that will do the job? That would be alot easier than messing with plastic.

[amideutch]

Plaz, check out this thread, especially the part about the pie tin. Ami
http://www.tomatoville.com/showthread.php?t=2883

[RDUN]

I definitely would not skip the plastic... it does a great job of retaining moisture and, as Suze said, keeping the fertilizer strip intact. Without the plastic, even with regular mulch, any rain will dilute the fertilizer prematurely.

Also, using the plastic with the GS containers allows you to fill them all the way to the top with potting mix... I assume the more mix the better. I usually put the plastic on before planting the plants... then cut an "x" where I want the plant to be and carefully remove a column of dirt down to the bottom of the soil chamber, and stick the plant in.

It is a little bit of a hassle to get set up, but once it's done... it's a very neat and tidy set-up.

[rzr]

Prevents Cracking: Which is one of the major benefits. Since it prevents rain and over waters the plant, the plant gets only the exact amount of water it needs consistently from the water reservoir.

[Tomstrees]

was a question I've been looking to find answers too ~

I have bins - but no plastic - I was just going to use straw mulch ...
Prolly the same right ?


~ Tom

[sirtanon]

Not the same, Tom.. definitely work very differently.

If you want an easy and inexpensive source of plastic for use in the bins, you can do what I do... Get yourself a box of Tall kitchen garbage bags for a few bucks. They're white, so they reflect light up nicely, they're just the right size, and they're cheap one bag can be cut along the seams to make for two plastic mulch sheets.

Otherwise, if you want thicker/darker, you can always get a box of Hefty garbage bags.

[RDUN]

If you're into the colored plastic mulches (GS sells the red with their "Tomato Success Kit") you can buy red, black, white, or silver by the foot here:
http://www.superseeds.com/products.php?cat=19

Plaz: One other thing I would mention regarding the GS self-watering containers that I did wrong the first year because I didn't fully read the insructions: Inside the container there are two conical shaped legs that support the black divider between the water and soil. You need to drill about a 1/4" hole in the top of these legs. This hole acts as an overflow to keep you from putting too much water in them. When they are full the water will just drain out the bottom. I didn't do that last year and I think my containers were overfilled a couple of times which would make the soil waterlogged. If you haven't already done so you could probably go up from the bottom of the container and poke/drill the hole from the bottom.

[Plaz]

Another stupid question, I put the plastic down, then the plastic mulch. It then rains, I still get as much rain water in my container as I would without the plastic don't I? Or is the plan that the rainwater pools some on top then evaporates? I just dont see how it will keep rainwater out of the container? I can see the benefits of warming the soil and weed control (although, I thought containers were pretty much weed free?) Please be gentle, as I'm new at this and just trying to get it all figured out.

P.S. Bought 2 bags of plastic mulch, that stuff ain't cheap $23 for it at H Depot. Still trying to decide if I'm going to use it. As it is, I think I will have the most expensives tomatoes on the face of the earth this year!

[RDUN]

I'm a little confused when you say you used plastic AND plastic mulch. When you use a plastic film (trash bag, red plastic film, or similar) the film IS your mulch... no additional bagged plastic mulch is necessary.

With regards to the rain water... yes I would say that the rain would still make it's way to the soil along the sides of the container where the plastic film is tucked in. But, if you have your overflow holes, it cannot overfill. Also if you have a fertilizer strip on top of the soil as the Earthbox instructions call for, the plastic will keep the rain from falling directly onto the fertilizer strip and thereby dispersing it into the soil prematurely.

Make sense?

[Plaz]

Yes and no. I'm not using Earthboxes but the ones from Garden Supply. Mine didn't come with any type of lid or plastic cover. I was thinking of putting plastic film down, then got to reading, then I thought about just the plastic mulch. So far I've done neither but have both. I'm thinking about using plastic film and regular old wood mulch (much cheaper). I keep hearing about this fertilizer strip; I just mixed my fertilizer (5-2-2 I think it was) throughout the box and don't really have a concentration of it anywhere. What I had planned doing was to either add liquid type of fertilizer to the reservoir or just add some to the top of the box later on (if I don't cover with plastic/mulch); if it seemed the plants were in need of it.

Right now I just read forum posts and try to learn how to do this, close to right, the first time.

[RDUN]

Let me reiterate: The plastic film IS mulch. Mulch is any covering that prevents evaporation of water from the soil and prevents weeds from emerging...both of which are accomplished with the plastic film. No additional mulch in the form of straw, wood chips, grass clippings, etc. is necesarry. I'm using the same containers as you with white plastic film:


The fertilizer strip that I and others are referring to comes from the instructions for the original Earthbox which can be used for these boxes as well:

earthbox_planting_instructions.pdf

[Plaz]

Wow nice plants!!! My bad, to me mulch is the ground up stuff. I'll probably just lay down white/black plastic film, then add some cheap wood mulch on top, just for looks. Will adding the mulch on top of the plastic be that bad of a thing, I know I lose the benefit of light reflecting?

My problem is the only place I have full sunlight is the front of the house and I'm afraid my wife will defecate a brick (if you know what I mean) when these plants take off. Can't wait to see the look on her face when I have to put cages up. I've always wondered if tomatoes can be grown in filtered sunlight in a hot climate. I'm in SC and wondered if the heat alone can produce tomatoes? I know it might not be a great producer, but wondered if it might work at all?