Traveling through the countryside, you may have seen fields of
beds covered with plastic film mulch. Or maybe you’ve read about
it in farm and gardening magazines.

Growing vegetable crops on plastic film mulch is common
throughout the Southeast. But up to this point, few have chosen
to use plastic in their gardens. You may feel you need to know
more about its benefits and possible disadvantages.

Why use plastic?

Farmers are growing thousands of acres of vegetables on plastic.
So why do they use it? For farmers, plastic film mulch:

1. Promotes earlier production in the spring.
2. Often increases yield over bare-ground production.
3. Reduces weed problems.
4. Reduces fertilizer leaching.
5. Reduces evaporation of soil moisture.
6. Reduces soil compaction.
7. Eliminates root pruning from hoeing and cultivation.

Plastic film mulch provides these same benefits to gardeners. But
let’s look a little closer.

Most Helpful Factors

All seven factors on this list are helpful. Because plastic mulch
warms the soil and enhances early growth, spring vegetables grown
on plastic can often be harvested 10 days to two weeks earlier
than those grown on bare ground.

Historically, buyers pay higher prices for earlier-harvested
produce. Now, that’s important to commercial growers. It’s the
main reason they use plastic.

Second in importance to growers are increased yields, which mean
more products to sell and more profits.

Reducing weed problems comes in third. However, weed problems are
reduced only if you use a black mulch or some other
wavelength-selective mulch that blocks photosynthesis.

Even those aren’t perfect. Nut sedges are some of the most
troubling and most persistent weeds in gardens. And plastic mulch
doesn’t slow them down.

Definite Downsides

Those are the major advantages. But that’s only part of the
story. There are downsides.

Plastic has to be installed very carefully and precisely to very
stringent standards, or it can quickly become more a curse than a
blessing.

To be effective, the plastic needs to be on raised beds and must
be installed tightly to the bed. There must be plenty of soil,
too, on the outside edges holding the plastic down, or it
probably will blow into your neighbor’s yard with the first wind
gust.

Commercial growers have to install plastic to these same ridged
standards. But they have the machinery to throughly and properly
till the soil, make the required bed and properly place and
secure the plastic.

Hard to Do by Hand

Since most gardeners don’t have this specialized, very expensive
equipment, these chores must be done by hand. From experience, I
can verify that these are very hard, physically demanding
tasks.

For those willing to make a substantial investment, at least one
company has begun marketing “garden-sized” equipment for making
beds and laying plastic. Check with your garden supplier for
availability and costs.

Getting water under the plastic mulch can be a problem, too.
True, the mulch helps conserve soil moisture. But eventually it
will become depleted. It’s hard, or impossible, for rain or
overhead irrigation to adequately wet the soil under the
plastic.

Drip Irrigation Necessary

That’s why farmers install drip irrigation tubes under the
plastic. Gardeners who grow on plastic should use drip
irrigation, too.

Another downside is that most plastic mulches aren’t
biodegradable. At the end of the garden season, you have to
remove and properly dispose of (not burn) the plastic. Again,
this can be quite a chore.

Next spring, when it’s decision time, review this list of
benefits. Then carefully consider the chores of tillage, bed
preparation and plastic installation. Weigh all these factors in
the balance.

Some gardeners will elect not to use plastic film mulch. Others
will decide the positives outweigh the negatives. The decision is
yours.