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Bell peppers grow big and beautiful over plastic film mulch. But is growing on plastic mulch worth the effort in your backyard garden? |
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:
- Promotes earlier production in the spring.
- Often increases yield over bare-ground production.
- Reduces weed problems.
- Reduces fertilizer leaching.
- Reduces evaporation of soil moisture.
- Reduces soil compaction.
- Eliminates root pruning from hoeing and cultivation.
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.
