Plastic mulch in SWC

16 years ago

I compared SWCs with plastic mulch and without plastic mulch. Thinking that without plastic mulch the soil mix would be better aerated. And since it's a SWC it will be getting all the water it needs anyway and doesn't need the plastic mulch. The plastic mulch on the originally earthbox designs was just for top fertilizing and keeping out rain water.

Here are pictures from back in May.

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Here are the plants now.

First the plastic mulched one:

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Next the un-mulched one:

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To my surprise the mulched ones have done much better. Bigger plants, bigger fruit set.

My theory is that the plastic mulch captures the evaporation and thus keeps the top of the growing mix wet.

So the plant roots have more mix to grow in. The top inch or so of the un-mulched SWC mix would be completely dry.

Any other theories?

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Comments (7)

rhizo_1 (North AL) zone 7
16 years ago
The plastic 'mulch' will also warm up the soil quite a bit, too, even though it's white. Then, speaking of white, that color will reflect sunlight back onto the underside of the foliage...providing a nice oomph to your plants in the form of enhanced photosynthesis opportunity.
emgardener
Original Author
16 years ago
Hadn't thought about the extra reflection angle. Could be a reason for the difference.

Used white because I didn't want the soil to heat up to much.

I tested the soil temperature difference (with my finger) and yes the plastic mulched one was warmer. This caused the plants to grow faster initially when it was still cold out in May and June.
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thegreenone
16 years ago
emgardener can you tell us about what kind of fertilizing method did you use here. obviously u can't have the fertiligzing strip without the mulch. the big question here is did you apply the fertilizing strips in the mulched container? if two diffrent fertilizing method the mulch comparision is not valid in my opinion.
emgardener
Original Author
16 years ago
No fertilizer strips. Just used Foliage Pro, diluted and poured directly into the reservoir. Added the FP whenever the leaves looked like they needed a boost.
thegreenone
16 years ago
ok, very big diffrence then. btw any reason not to use the strip? have you tried with strip, did it gave you bad restults?
calistoga_al ca 15 usda 9
16 years ago
I use the black plastic cover with fir bark on top of that. For initial fertilizer I used landscape type time release with a six to nine month time frame. On the theory that the roots will grow best where the fertilizer is, I applied it in columns toward the ends of the box away from the wick, about midway in the soil depth. I believe the plastic is important in helping the wick lift the water to the top, making the soil moisture more uniform. I have been adding Foliage Pro weekly with the water because our summer has been so cool I am concerned about the time release being slow. I am happy with the results. Al
emgardener
Original Author
16 years ago
thegreenone,

I never used a fertilizer strip. Started with solid organics, didn't work too well, went to time release fertilizer, but found it hard to keep the right amount. So now I just use foliage pro. It's relatively easy to just watch the plant leaves and see when they need a boost.

But as some of my other posts indicate I'm now trying more liquid organics in larger containers.