- Plastic Mulch Pros And Cons: Should You Use Plastic Mulch
- Plastic Mulch Pros
- Plastic Mulch Cons
- Plastic Mulch Issues for the Commercial Grower
- Plastic Mulch Cons for the Home Grower
- Are Plastic Mulch Issues Enough to Dissuade You?
- Respect the soil in your garden: Don’t add plastic to it
- Review Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation?
- Plastic Mulch Films
- Biodegradable Plastic Mulch
- Crop Production
- Application and Cultural Systems
- Benefits and Drawbacks
- Plastic Mulch Products
- Clear Plastic Mulch
- White Plastic Mulch
- Silver/Metallic Plastic Mulch
- Colored Plastic Mulch
- Biodegradable Mulch
- How to clear land using black plastic
- Plants can grow under blue or light coloured plastic
- Leave the plastic on the ground for 2-3 Months
- Dead plants can be dug back into the soil
- A new raised bed in an area that was once weeds
- Experiments With Plastic Organic Mulch in the Garden
Plastic Mulch Pros And Cons: Should You Use Plastic Mulch
Using plastic for mulch isn’t a new idea. Commercial farmers have used it for decades. But it is finding its way into home gardens, where it finds friends and foes. The benefits of plastic mulch include increased and earlier crop yields. But do these outweigh the disadvantages? Some feel that the advantages of inorganic mulch outweigh the drawbacks for many crops in certain circumstances. Where do you come out in weighing plastic mulch pros and cons? If you aren’t sure, you’ll find the top arguments on both sides right here.
Plastic Mulch Pros
Teo’s viewpoint: No matter what you think of the organic vs. inorganic argument, the benefits of plastic cannot be denied. Using plastic mulch over soil keeps people from walking in the area, preventing compacted soil. It also warms the soil, keeps down evaporation and virtually eliminates weeds.
Warming the soil. All mulch serves to regulate the temperature of the soil. One of the advantages of inorganic mulch, and benefits of plastic mulch, is that it warms the soil as much as 5 degrees F. What effect does this increased warmth have on vegetables? It means you can plant them earlier than you could without the mulch. In fact, if you grow warm-season vegetable crops with black plastic mulch, you’ll usually get higher yields. You’ll also be able to harvest up to three weeks early.
Reducing evaporation. One of the reasons you use any mulch is to help the soil hold moisture. So yet another of the plastic mulch pros would be that it cuts down on evaporation by some 70 percent. This is one of the best reasons for plastic mulch use. Reduced evaporation will cut your water bills, reduce your water consumption and prevent the leaching of nutrients. But you’ll need to install drip irrigation systems under the plastic, since it won’t let rain seep through.
Eliminating pesky weeds. Weeds are not friends of vegetable gardeners. They compete with the young vegetables for water and nutrients, and they can also shoulder or shadow out tender crops.
One of the best plastic mulch pros is the fine job it does at taking out weeds. That means you won’t be out there on your knees weeding and you’ll use less herbicides. Your vegetables will be healthier. Since some insects eat weeds and others use them for laying eggs, you’ll have less pests to worry about too.
Plastic Mulch Cons
Amy’s viewpoint: I definitely see the benefits of mulch in the garden; I’m just not as big of a fan about the recent popularity of plastic mulches. Plastic mulches have their cheerleaders, I just don’t happen to be one of them. Yes, they increase soil temperature so earlier crops are possible, they retain moisture and retard weed growth, but I see many problems with plastic mulch.
Plastic mulch comes in two basic types: black polyethylene film and clear polyethylene. Black plastic is used to retard weed growth, retain moisture, and heat up the soil. Clear plastic does not suppress weed growth, but it is also used to raise the soil temperature. Using polyethylene film as vegetable mulch actually has its roots back in the 1950’s. Dr. Emery M. Emmert of the University of Kentucky was one of the first to recognize the benefits of using both low-density polyethylene (LDPE) and high-density polyethylene (HDPE) films as mulch. He also was interested in and wrote about using plastic for greenhouses and was eventually dubbed the “plastic surgeon.” All jokes aside, there are a number of problems with plastic mulch.
Plastic Mulch Issues for the Commercial Grower
Plastic is costly and doesn’t break down. First of all, plastic mulch is quite a bit more expensive than other mulch products. It does last longer, but that is because it doesn’t naturally degrade as organic mulches do. Organic mulches may have to be replaced each year, but as they break down they are enriching the soil and feeding all the beneficial bacteria. Since plastic mulch doesn’t break down naturally, it must be removed from commercial fields annually; a costly practice.
The process of proper placement of plastic is in itself a significant plastic mulch issue. It requires specialized equipment and additional labor as does the removal of the mulch from the field after harvest. Plastic mulch is used in conjunction with drip irrigation, not in and of itself a bad thing, but it does increase the cost of production since the drip system must be removed when the plastic mulch is during post-harvest.
Plastic is more difficult to dispose of. Another downside of plastic mulch is disposal. Not only is it time consuming to remove plastic mulch from a field, but great care must be taken to avoid leaving sections of plastic in the field. Not only are these remains unsightly, but they do not decompose and should not be tilled into the soil. Disposal of plastic mulch definitely raises environmental concerns since the plastic does not degrade. Instead, it becomes a part of the ever increasing landfill system. And many landfills require payment for disposal, yet another added cost.
Plastic Mulch Cons for the Home Grower
Some of the problems listed above will pertain to the home grower but because everything is on a smaller scale, here are some plastic mulch cons for the home grower to consider:
Plastic mulch can get too hot. While black plastic mulch is ideal for heat-loving veggies like tomatoes, peppers and melons, it isn’t suitable for those living in warm climates; the plants will likely get scorched. Plastic mulch is also not appropriate for cool season crops such as lettuces, peas and root veggies because the soil warms too much.
Sometimes too much moisture is a bad thing. Yes, plastic mulches can reduce soil evaporation, but plants in plastic mulch also don’t easily get irrigation from rainfall or overhead sprinklers. Instead, the home owner will have to go to the extra time and expense of installing soaker hoses or drip irrigation around each plant. Additionally, since moisture doesn’t evaporate, it is easy to overwater and drown plants. Ultra-damp conditions can foster fungal diseases too.
More difficult for plants to obtain nutrients. Fertilizing plants under plastic mulch can be a nightmare. The holes around the plants just aren’t large enough to side-dress without burning the plants. While plastic mulch retards weeds, when you cut a hole in it to plant your veggies, weeds can and will enter into that soil window. This means they may grow in close proximity to the crop, competing for nutrients and water.
Now I’m not some rabid environmentalist, but I am a concerned human being. I can’t support an inorganic, expensive, product that is fostering the use of landfills, landfills that never seem to go away, ever – especially given that estimates for the complete breakdown of plastic ranges from 450 years to 1,000. Of course, that’s only a guess because plastics have only been around for maybe 100 years. Hey, but I must be in the minority. Approximately 2,500 square miles (6,500 km.) of agricultural lands use polyethylene mulch. What’s next? Mulching with tires? Oh wait, that’s already being done. It must be much better for the earth…tires only take between 50 and 80 years to degrade.
Are Plastic Mulch Issues Enough to Dissuade You?
Obviously, there are strong opinions when it comes to using plastic mulch in the garden. It certainly has its share of benefits, but then again many of your organic mulch products can serve these same advantages. And plastic mulch definitely has its opponents, with a number of downsides that are worth consideration. Ultimately, however, it’s an individual choice but one that should be made easier with two sides of the story.
Respect the soil in your garden: Don’t add plastic to it
Before it’s too late, I must address one of my pet peeves: deliberately putting plastic in soil.
Take, for instance, black plastic sheeting sold as mulch. This stuff appears at first to be a cure-all for weed problems. Lay it on the ground, cut holes only where you will set plants, and weeds will die from lack of light, presumably ending all your weed problems for years to come.
But other problems arise. An impermeable sheet of plastic over the ground can leave plant roots and soil microorganisms gasping for air. Roots set in the openings might develop even greater breathing problems when all the water falling on the plastic floods those holes.
And the plastic eventually starts to tear and break apart, which creates a general mess.
Geotextiles, introduced more recently, are offered as an alternative to solid black plastic sheeting. These are woven or spun plastic fabrics that resist tearing and have many small holes to allow passage of air and water.
Both black plastic and geotextiles are widely used by farmers, gardeners and landscapers. If you don’t like the way these synthetic mulches look — surely the case when they are used in landscaping — you cover them. Wood chips look natural and are widely used for this purpose. And anyway, geotextiles need a thin cover of something to shade out the minimal light that makes its way through the tiny holes.
But problems arise again. Over time, plenty of weeds eventually sneak in to grow in the wood chips covering the plastic. Over time, the chips or other coverings also slide around to expose the plastic or geotextile beneath — not a pretty sight!
Furthermore, even if black plastic or geotextiles don’t do their jobs forever, they’ll be in the soil that long, or almost. Try to make over the landscape in the future and you will be wrestling with and cutting geotextiles or collecting scraps of black plastic.
PLASTIC PEANUTS, NO
Another, fortunately less frequently suggested use of plastic in the soil is plastic “peanuts.”
Mixed into the soil, the reasoning goes, they should increase aeration. While they would undoubtedly make a soil lighter, and thus seemingly better aerated, all that extra air is pretty much locked up in the peanuts.
It has also been suggested that a layer of plastic peanuts be put in the bottoms of flowerpots to enhance drainage, as layers of gravel have been used. In this case, that layer of peanuts is worse than useless, just as the traditional layer of gravel was. The effect in both cases is to create a “perched” water table inside the pot, giving the roots less depth of well-aerated soil.
Also, spent potting soil can be spread on the ground or added to a compost pile, but do you want the peanuts there also?
ENVIRONMENTALLY FRIENDLY ALTERNATIVES
Enough plastic makes its way into our soils inadvertently, from misplaced plant tags to those stickers now ubiquitous on fruit skins to pieces of old plastic pots.
Deliberately embedding a permanent, synthetic blanket in the ground or mixing plastic peanuts into the soil brings no benefits that could not be had in a more nature-friendly way. Paper mulch, for instance, biodegrades and can stave off weeds for a season. Perlite or vermiculite are two minerals that can lighten a soil more effectively than styrofoam peanuts.
Removing plastic put on or in the soil becomes difficult or well-nigh impossible.
Deliberately putting plastic in the ground is disrespectful of the skin — that is, soil — that covers our planet and sustains much of the life here.
Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation?
Plastic mulching has become a globally applied agricultural practice for its instant economic benefits such as higher yields, earlier harvests, improved fruit quality and increased water-use efficiency. However, knowledge of the sustainability of plastic mulching remains vague in terms of both an environmental and agronomic perspective. This review critically discusses the current understanding of the environmental impact of plastic mulch use by linking knowledge of agricultural benefits and research on the life cycle of plastic mulches with direct and indirect implications for long-term soil quality and ecosystem services. Adverse effects may arise from plastic additives, enhanced pesticide runoff and plastic residues likely to fragment into microplastics but remaining chemically intact and accumulating in soil where they can successively sorb agrochemicals. The quantification of microplastics in soil remains challenging due to the lack of appropriate analytical techniques. The cost and effort of recovering and recycling used mulching films may offset the aforementioned benefits in the long term. However, comparative and long-term agronomic assessments have not yet been conducted. Furthermore, plastic mulches have the potential to alter soil quality by shifting the edaphic biocoenosis (e.g. towards mycotoxigenic fungi), accelerate C/N metabolism eventually depleting soil organic matter stocks, increase soil water repellency and favour the release of greenhouse gases. A substantial process understanding of the interactions between the soil microclimate, water supply and biological activity under plastic mulches is still lacking but required to estimate potential risks for long-term soil quality. Currently, farmers mostly base their decision to apply plastic mulches rather on expected short-term benefits than on the consideration of long-term consequences. Future interdisciplinary research should therefore gain a deeper understanding of the incentives for farmers and public perception from both a psychological and economic perspective in order to develop new support strategies for the transition into a more environment-friendly food production.
Plastic Mulch Films
Plastic mulch is generally 1.0-1.5 mils thick, 4-6 feet wide, in rolls 1,000-4,000 feet long. It is available in a multitude of colors ranging from clear (transparent) to opaque (black or brown). Recently, colored mulches have been investigated for their influences on insect control and plant yields. For example, reflective or silver mulches have been shown to reduce the incidence of onion thrips. Check with your local extension office for the most recent research findings proven to work in your area.
Plastic mulch functions to warm the soil, conserve moisture, and prevent nutrient leaching. Clear plastic has the highest soil warming capability (8º-14º F over bare soil), but weed growth underneath can be extreme. An herbicide is necessary to keep weeds under control with clear mulch. Black mulch will prevent weed growth by prohibiting light transmittance to the soil and will warm the soil 3º-5º F over bare ground.
Wavelength selective or near-infrared transmitting mulch (formerly referred to as IRT mulch, but now “IRT” is part of a trade name) is a “hybrid” of black and clear mulch characteristics. Specific pigments incorporated into the film during manufacture selectively block out blue and red wavelengths of light (which cause weeds to grow). This inhibits weed growth similar to black mulch. At the same time, infrared light is transmitted through the mulch warming the soil (similar to clear mulch). The wavelength selective mulches are generally brown or green in color. However, don’t purchase them on color alone. The pigments embedded in the plastic impart these specific properties. Commercial recommendations are to lay wavelength selective mulches 7 days prior to transplanting. Within reason, the additional cost for this mulch film is compensated for by increased yields due to early soil warming. On small farms or in small fields, black, brown, or wavelength selective mulches are often the preferred way to eliminate the use of herbicides. This is a viable option for weed control on many organic farms. Crops that respond best to mulching are those that require higher soil temperatures (muskmelon, watermelon, cucumber, squash, tomato, pepper, and sweet corn).
Apply plastic mulch after fields have been leveled, smoothed, and fertilizer has been applied, and when there is good soil moisture. In the case of black mulch, good uniform soil contact is essential as the soil is warmed by heat conduction. Commercially, the simplest way to apply mulch film is with a mechanical mulch layer. Hand application is an option, but applying more than a half-acre can be difficult and time consuming.
Generally, plastic mulch is laid in the spring as soon as the land can be prepared. However, some spring seasons are wet and can delay normal land preparation and planting activities. An alternative is to lay plastic in the fall. Fall mulch application will require similar land preparation as in the spring, but use of a cover crop between the rows is recommended to prevent soil erosion. Oats will winter kill, but winter rye will require Roundup or Gramoxone applications in the spring to knock down.
After harvest, plastic mulches should be removed from the field and disposed of properly according to local ordinances on incineration, landfills, and open burning. Alternatives to removing plastic from fields are biodegradable mulch films and recycling programs to alleviate landfill accumulations. Research is ongoing for both of these options.
Biodegradable Plastic Mulch
Degradable plastic mulch has been in development for decades. Some of the first commercialized products were photodegradable, and would break down when exposed to light. Many growers who used these products reported uneven and incomplete breakdown, particularly after tillage buried the plastic fragments at the end of the season. However, degradable mulches prepared from biodegradable polymers now exist. They are designed to be tilled into the soil after their service life, after which they will undergo aerobic biodegradation by soil microorganisms, producing CO2, water, and microbial biomass.
The most widely available and studied biodegradable polymer is Mater-Bi, made in Italy by Novamont. Some mulches that use this polymer are Bio360 and BioTelo (Dubois Agrinovations) and BioAgri (BioBag Americas). Mater-Bi is made primarily from starches, cellulose, vegetable oils plus proprietary biodegradable complexing agents derived from renewable, synthetic, or mixed sources. While Bio360 mulch is approved for use on European organic farms, at this time no biodegradable plastic mulch is approved for use on USDA-certified organic farms. This is because currently available biodegradable plastic mulches have a maximum 25% biobased content while one of the requirements of National Organic Program is that the mulch must be completely biobased. Further, most commercially available biodegradable plastic mulches are produced through fermentation using genetically modified yeast and bacteria for increased productivity, and that is not allowed in US organic agriculture. US organic regulations do allow the use of synthetic (polyethene) mulches, but they must be removed from the soil at the end of the growing season.
Researchers at Cornell University, Washington State University, and University of Tennessee have shown that the biodegradable plastic mulches performed comparably to polyethylene mulch in controlling weeds, raising soil temperatures and increasing crop yields despite some breakdown of biodegradable mulch during the growing season. As biodegradable mulch starts to degrade during the growing season, mulch adhesion to fruit surface can be an issue for heavy-fruited crops like pumpkin and watermelon, where fruits rest on the mulch for extended period. Up-to-date information can be accessed at www.biodegradablemulch.org.
Biodegradable mulches can range from 2-3 times the cost of standard black plastic, but end-of-season labor and disposal costs are avoided. The mulch is thinner (it comes in 0.5-0.8 mil thicknesses) than typical black polyethylene (1.25 mil), and when starting to lay the plastic, extra care is required to prevent tears. When laying mulch, do not stretch as tightly as you normally would with black plastic (see mulch installation video at https://ag.tennessee.edu/biodegradablemulch/Pages/Videos-relating-to-Biodegradable-Mulch.aspx). Applying in early morning when temperatures are cooler can help. The mulch starts to break down more quickly when stretched. Apply right before planting because the mulch will start to break down as soon as it makes soil contact. Buy what you need each year – do not try to store biodegradable mulch. The mulch can start to break down in storage, particularly if storage conditions are moist and/or warm. Store the mulch upright, on ends of rolls. The mulch can start to degrade or stick together under pressure of its own weight.
WeedGuardPlus (Sunshine Paper Co.) is a brown paper mulch with soil cooling properties. It is OMRI listed and is effective under low rainfall and low wind conditions. WeedGuardPlus is also effective in controlling nutsedge unlike polyethylene and biodegradable plastic mulches. However, it is even more expensive than biodegradable plastic mulch and typically comes in 500 ft rolls.
The use of plastic polyethylene mulch in fruit and vegetable production is a common practice in Alabama. Among the crops for which it’s used are strawberry, watermelon, muskmelon, tomato, pepper, cucumber, squash, and brassicas such as collards, broccoli, and cabbage. Successful application requires an understanding of (a) how to use plastic mulch, (b) what the benefits and drawbacks of its use are, and (c) what types of plastic mulch products are available.
Application and Cultural Systems
The most widely used and economical plastic mulches are embossed black polyethylene films with irrigation drip tape installed under the mulch (Figure 1). Mulch is usually applied by a tractor-drawn mulch layer implement, which lays the plastic and drip tape into beds while anchoring the edges with soil (Figure 2). It is important that soil is well prepared before laying the plastic mulch to ensure a tight fit between mulch and soil. Any clumps of grass, sod, weeds, or soil make proper application difficult. All chemicals and most fertilizers should be applied during bed preparation. The remaining fertilizer can be applied throughout the growing season as a soluble liquid added through the drip irrigation system using a fertilizer injector. Supplying fertilizer through the drip irrigation system is crucial in sandy soils where any initial fertilizer is likely to leach away from the plant root zone. Management of weed growth in the alleys between mulch beds is important. Tactics for controlling these weeds include mowing, cultivating, using organic mulch, cover cropping, or using herbicides approved for row middles. Weeds that emerge in planting holes in the mulch should be removed by hand early. This especially applies to vining weed species such as morning glories and bindweeds. Plastic mulch can be double cropped, meaning a second crop can be grown on the mulch after the first is harvested. Fertilization for the second crop should be applied through the drip irrigation system.
Benefits and Drawbacks
There are many benefits to growing vegetables on black plastic mulch:
- Soil temperature in the bed is increased, allowing for faster development and earlier crop yields in spring and early summer.
- Weed growth around crops is inhibited.
- Crops are kept clean.
- Fungal disease is prevented through reduced soil splashing.
- Soil moisture is better retained.
- Soil compaction is prevented.
- Erosion and leaching is reduced.
Disposal of plastic mulches is among the biggest challenges of this technology. Removal from fields is time-consuming and expensive. Polyethylene plastic is not biodegradable and not readily recyclable. As such, most plastic mulch is either disposed of in landfills or stockpiled. Mulch removal at the end of the season is required for certified organic growers. Beyond the challenge of disposal, the major drawback to plastic mulch systems is the initial cost of specialized equipment, including a mulch applicator, the mulch and drip tape, a transplanter, and a fertilizer injector.
Plastic Mulch Products
The most common plastic mulches used are plain or embossed black polyethylene films between 0.8 and 1.25 millimeters thick and 4 feet wide. Black mulch will raise soil temperatures from 3 to 5 degrees F. Black plastic is the least expensive option, but different mulch products can provide other properties:
Clear Plastic Mulch
These mulches transmit solar radiation to the soil and block the radiation from escaping. This creates a mini-greenhouse under the mulch. Soil temperatures can be 8 to 14 degrees F higher while using this mulch. The downside is that clear plastic mulches allow light to penetrate, which promotes weed germination and growth. Weeds eventually tear the plastic and compete with the crop. Clear plastic mulches are not recommended in Alabama due to weed issues. They can be useful, however, if applied during hot weather as a way to solarize soil and kill plant pathogens and some weed seeds.
White Plastic Mulch
These mulches reflect incoming solar radiation. Soil underneath white plastic will therefore be cooler compared to bare soil. White or white-on-black mulch is commonly used for fall crops when soil is already warm during establishment and black plastic has the potential to overheat plant roots.
Silver/Metallic Plastic Mulch
Research has shown that silver mulches confuse and repel plant pests, such as aphids and flower thrips. This product can be useful when growing peppers or tomatoes, as thrips are the main vector for tomato spotted wilt virus. Silver mulch also encourages early fruit ripening by reflecting light back to the canopy. Soil under silver plastic will be several degrees cooler than soil under black plastic. Infrared-Transmitting (IRT) Plastic Mulch These films absorb certain colored wavelengths but transmit heat (infrared) radiation to the soil. The materials heat soil as efficiently as clear mulches but reduce the weed germination issues.
Colored Plastic Mulch
Red, blue, orange, and yellow mulches produce distinct radiation that reflects into the crop canopy. Research into colored mulches has shown inconsistent results, however, and they are not widely used in Alabama.
These mulches were developed in response to removal concerns of plastic mulches. They are designed to be tilled into the field and break down over time in the soil. The products can perform as well as polyethylene mulches in heating soil and preventing weeds, but they cost significantly more. None of these products currently meet National Organic Program (NOP) standards for use in certified organic systems.
Black plastic laid can kill grass and weeds to make space for a vegetable garden. It’s an eco-friendly way to clear land without having to use herbicides.
Once the excitement of starting a new garden wears off for beginner gardeners, the questions begin. One of the most common is ‘What’s the first step?’. How do I convert a piece of lawn or overgrown allotment into a productive garden? The best way to start is to remove the vegetation and especially the perennial weeds. If your goal is to grow organically, there’s an easy way for you to do this — suppress the weeds with Black Plastic Sheeting.
This is exactly how I created my own vegetable garden. It saved me both time and energy and is the way I recommend for clearing any land without using herbicides. The before and after photos below show how I covered the entire area and then gradually peeled the plastic back. Bit by bit I transformed a weedy plot of land into a beautiful and productive veggie patch.
Black plastic sheeting cleared this plot of weeds and grass. It made creating a new vegetable garden easy and eco-friendly.
How to clear land using black plastic
- Mow the area or strim it so that the weeds and plants are low to the ground
- Lay heavy duty Black Polythene Plastic Sheeting on the ground and weight it down
- Leave for 2-3 months in summer or six months in winter
- Lift the plastic, remove slugs, and dig up perennial weeds
- Dig over the soil and prepare it for planting
No need to break your back digging weeds out. Just cover the soil with black plastic to kill weeds.
After a couple months of being covered, this area is nearly completely free of grass and weeds.
Plants can grow under blue or light coloured plastic
I’ve gradually been settling into my new allotment plot but one corner of it is still unused. To help get it ready for growing, I’ve covered it and the compost pile beside it with a layer of heavy duty black plastic. This is the kind of stuff that you’ll find as pond or roof lining and will hold out well in the elements.
Thin black plastic, like bin-liners (garbage bags) are not suitable since they rip and shred and will cause a lot of litter. Blue tarps and light coloured plastic isn’t great either since some plants will still grow under it.
Only the hardiest of perennial weeds can survive. They’re easy enough to dig out afterwards though.
Leave the plastic on the ground for 2-3 Months
Once the plastic is laid out and weighed down, you just leave it and let it do its work. Because the dark colour stops sunlight from getting to the plants below, most of the plants die off. Grass and annual weeds are the first to go but hardier weeds can take longer. In warmer months it can take as little as two months for the plants underneath to die and rot down. In winter leave the plastic for around six months.
Some weeds will survive the apocalypse and even after a year of being covered, the Dock on my plot is still alive. They show up as white and yellow stems as I lift up the plastic so they’re easy to spot and dig up. Slugs and other pests are easy to see when you lift the plastic too. Take the time to remove and destroy them and you’ll save yourself the pain of them multiplying and eating your veg.
In case you were wondering, the plastic only dries the soil out when used in very large sheets. In smaller areas, like the one I’ve just dug over, the soil is moist and worms and other animals are unaffected.
It’s much easier to dig over the soil once most of the grass and weeds are gone
Dead plants can be dug back into the soil
After an hour of digging over the patch the area is good to grow. The dead plants and leaves left on the surface can be reworked back into the soil. However, the living perennial weeds including Dock and Creeping Buttercup need to be manually removed. I take mine to the city’s green waste bin and sometimes just bin them.
Dock is my particular garden foe and I’ve gotten to know this plant well over the years. The smallest piece of its root can sprout a new plant and in an ordinary compost pile they continue to grow. Be careful of where you dispose of it. Throw it to the side of your garden and it will set seed and recolonize your garden in no time.
After the beds were dug. Hardly a weed to be seen in those new growing spaces.
A new raised bed in an area that was once weeds
In an area that was just weeds is now a brand new raised bed. I used timber salvaged from my old plot to build it and the inside is filled with soil and rotted mushroom compost.
You don’t need to convert land into raised beds afterwards — that’s just my choice since I garden on a slope. What you will need to do is add organic matter such as garden compost, rotted horse manure, rotted mushroom compost to the soil. You can lie this on top and let the worms do their work. If you’re like me and have the New Zealand Flatworm in your garden you’ll probably need to dig it in a bit. New Zealand Flatworms have decimated my worm population.
From weedy land to garden bed, all it took was black plastic, a bit of time, and a fork over. If you’d like to clear land the organic way, this is the easiest way to go.
My garden now
Experiments With Plastic Organic Mulch in the Garden
May I draw a veil over our first year’s mistakes?
This year, with a little experience behind us, we started our garden just after the snow left the ground. First we cultivated the soil lightly, then put 10-foot-long strips of polyethylene down side by side with about a tenth of an inch between the edges. We planted early peas in this narrow “slot” and finished off that section of the garden by spreading about an inch of loose soil over the plastic to hold it down out of the wind.
One sunny but cold day shortly thereafter, we pushed a thermometer into the soil under the poly. It registered nearly fifty degrees. In unprotected soil nearby, the temperature was just over freezing. No wonder the peas germinated early!
Later we rolled out more of the poly and set onions through it. Since the onions were bigger and we wanted them farther apart than we had planted the peas, we simply made two-inch-long slits through the plastic for each onion and pushed the sets through the slits.
Don’t try sowing small seeds — even seeds as big as peas — through slits this way. If the poly sheet moves ever so slightly as it will when you walk on it (yes, we walk on ours . . . but only in soft, light shoes), the small seeds will not find their way up to the sunshine and the air. Instead, they suffer the fate of weeds and smother under the plastic. We lost a lot of our 1969 crop this way.
For parsnips, carrots and other small-seeded plants, we slit the black poly lengthwise into strips ten inches wide and ten feet long. We placed these strips side by side with their edges an inch apart and, as we did with the peas, we then planted the tiny seeds in the narrow slot of earth that was left.
By the way, there’s nothing particularly magic about the fact that we cut all our plastic sheets ten feet long. Our garden just happens to be that distance across. If your vegetable patch is twelve feet wide, cut your strips to reach. If the garden has exceptionally long rows, however, you may want to lay down a series of shorter pieces instead of one long strip of poly. Long strips are too liable to blow about in the wind . . . which always seems to get up just when the plastic is in the most awkward position. Your strips should simply be as long as you find convenient.
Convenience is worth looking for. When I was planting those onions I crouched down to cut the slit, then sat up straight, found an onion in the sack, planted that and — finally — moved on to the next position. Evelyn — attracted by my mutterings and groans — looked thoughtful for a moment, then brought out an empty five gallon drum from behind the barn.
“Here,” she said, “try this. Turn the drum on its side so it’ll roll and sit on it.”
I did as she said and found the small barrel to be a comfortable moving seat, easy to roll back along the poly as I continued to plant onions every six inches . . . until the school bus brought our daughter home. When she saw all the fun I was having-rolling along backward, sowing onions through the slits -she took over the task. I was demoted to scattering earth on top of the plastic strips to keep them down.
After the peas had been harvested, we rolled up the black poly to take a look at the weeds that had tried to grow under it. All of them were white from lack of light (a botanist would say “etiolated”) and most were lifeless. Without air and light, they could not survive. The weeds that had sprung up in the inch or two of soil covering the polyethylene had also quickly died . . . of thirst, as that shallow seedbed dried out.
A few weeds, of course, did grow between the edges of the polyethylene strips where the soil was left bare for the peas. Weeding here, however, was a small chore compared to the endless hacking with the hoe that would have been needed if we hadn’t used the plastic mulch. One or two stray volunteers sprouted up through the slits made for the onions, too, but they were easily pulled by hand.
Be that as it may, there was one weed that surprised us no end. As the summer wore on we came to ignore the volunteer plants that sprang up across the polyethylene because we knew they were growing in only an inch of soil and would soon die. One especially large and healthy volunteer did attract Evelyn’s attention, though, and she gave it a heave . . . only to find that the plant had sprouted through a hole in the plastic. We didn’t think much about it until, later, we found another weed . . . and another . . . and another . . . always the same kind of grass and always growing through a hole in the poly.
At last it dawned on us that this grass — later identified as “quack” or “twitch” grass — can actually push its way up through the plastic. We’ve since found that it will also creep out from under the edges of the poly. The survival mechanisms built into this grass are unbelievable.
Actually, the quack grass — although definitely hardy — is not the overwhelming danger it might seem and we only had our major troubles with it when we were breaking new soil. In our old plot, where we’ve gardened for years, the twitch grass has long been weeded out, so to speak.
We’ve also found that quack grass cannot grow through loose plastic and, after some time underneath, it dies. So now, in previously unworked ground where the grass may be lurking, we leave the plastic loose and keep it in place by burying the edges of each sheet a few inches deep. The strips billow up in a fresh breeze, but they stay put. Evelyn likes to lay a two-by-four on each loose piece of plastic when there’s a high wind but I don’t think it’s necessary. After a season with the poly buried only around the edges to kill off the twitch grass, we go back to the neater method of securing the plastic with an inch of soil across its surface.
What happens to the rain that falls on the poly? With the exception of a little that stays on top where the plastic is dished by irregularities in the ground, it seems that most of the water runs off the edges of the strips and soaks into the soil. To be sure, the small amount of rainfall trapped on top of each sheet evaporates . . . on the other hand, the plastic prevents a much larger evaporation from the soil and smother all the weeds that would otherwise drink the moisture in the earth. On balance, I don’t believe there’s any loss of water from the ground. The poly, in fact, seems to help the earth hold water, if anything.
Our success with black poly mulch was noteworthy enough this season to make us want to experiment further next year. We’re going to try to adapt the plastic to the flower beds for one thing, and it should be quite a challenge to get all the blooms in the correct position and the correct order.
We’d also like to try “sterilizing” an area by covering it with a 10-foot by 50-foot roll of poly. This should allow us to start a lawn free of dandelions, plantain and all the other weeds that compete for the space. This seems to us to be a better idea than poisoning the ground with weed killers.
Yep. We’re going to keep working with our newfound mulch. Plastic or no, it seems to give us good results. So good, in fact, that we just may run out of hanging, canning and freezing room if we aren’t careful!
For starters, skip the individual bags of compost and the plastic seedling pots.
Gardening is one of those soul-affirming, Earth-friendly activities that we’re big fans of at TreeHugger. Growing your own food (and flowers) is the most effective way to shorten the path from field to table, and allows you to control all of the inputs, from the kinds of seeds you plant, to the soil quality, to the type of fertilizer and compost, to the presence of plastic.
Yes, plastic unfortunately plays a major role in gardening. Think of all the little pots and trays in which seedlings come, the bags of compost, the tags and labels, the plastic-handled tools, and more. As useful as they seem in the moment, these are all unable to break down and contribute to the global plastic pollution crisis.
The good news is, it doesn’t have to be like this. There are steps you can take to reduce gardening-related plastic, some of which are outlined below.
– When setting up a raised garden bed, rather than spreading the bottom with black plastic to smother weeds, use flattened cardboard or thick layers of newspaper.
– Order topsoil, compost, manure, and mulch in bulk from a local supplier that will deliver to your site. Use a wheelbarrow to transport loads as needed. This spares dozens of plastic bags from being used.
– Buy plastic-free tools. Look for ones with wooden handles and metal ends. Use a metal watering can, which won’t go brittle and crack like a plastic one. Look for cotton canvas gardening gloves. Build a wooden compost bin. You can find lots of cool plastic-free tools at Lee Valley.
– Start your own seeds from paper packets. Use biodegradable seed cups or make your own from toilet paper tubes, egg cartons, or newspaper. You can also use a seed blocker or make seed balls. (More info on these methods here.) Beth Terry of My Plastic-Free Life also talks about Orta’s plastic-free self-watering seed pots, which look interesting.
– If you have to buy seedlings, see if a local greenhouse will start seedlings in wooden flats, then cut the plants out and wrap them in newspaper for customers. If not, ask if you can transplant from their container to your own non-plastic one before taking them home. If you must accept plastic containers, return them to the gardening center afterward, so they can be reused. Always look for containers made from recycled plastic.
– Ask suppliers about their packaging. When ordering bare-root shrubs, roses, trees, hedging, and more, inquire whether they come wrapped in plastic or paper.
– Skip the plastic hose and install an outdoor water tap or spigot. Use a metal watering can or bucket and ladle to water your garden beds if they’re not too extensive.
– Avoid plastic-coated trellises for plants like tomatoes, peas, and beans. Buy uncoated metal cages, wooden stakes, or concrete reinforcing wire.
– Make your own plant markers from popsicle sticks, wooden craft sticks, or write on the backs of old plastic ones that you might have kicking around.
– Start your own seed bank by storing seeds for later planting in glass jars.
Please share any thoughts or suggestions on plastic-free gardening in the comments below.