Gardening with Plastic Mulch

Gardening with Plastic Mulch

Plastic Garden Mulch

Gardening with colored plastic mulches

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We have been gardening with plastic mulch for close to 20 years now. And yes, that is a picture of my personal garden several years back.  I am so glad that we found it. Our garden is healthier, more productive and easier to manage. Plus, it cuts our water bill way down.

We have changed the way we use the plastic mulch through the years. At first, we just mounded up our beds and put the mulch over the dirt – no edging. We used ground staples and placed a brick on each staple. The previous homeowner had left a big pile of bricks that we used.

Now we have raised beds edged with concrete blocks. The first couple of years we only had one row of blocks (see picture of my garden below). We have since increased that to 2 rows with a concrete cap on top. It makes It easier to kneel and to just sit down and garden. We still use the ground staples. We place them at 18” spacing. Then we place rebar on the edges all the way along the raised bed.

gardening with plastic mulch

Plastic Garden Mulch

No matter which way we used we have never had any mulch blow off the beds. It stays nice and secure especially when the plants start growing and you put cages around them.

Benefits of Plastic Garden Mulch

I don’t have any scientific evidence, but our plants are pretty much disease and pest free. I can’t remember the last time we had an issue. We did have some tomato hornworms for a couple of years, but they have been gone now for years.

  • Water is conserved. Evaporation is slowed due to the plastic mulch. Therefore, you do not have to water as long or as frequently. Please note that water will not pass through the mulch so you will need a watering system underneath it. We use a Drip Tape System on a timer. Even in the hotter summer months we only water for 30 minutes every other day. You should determine your own watering schedule based on your plants and their needs.
  • Weeds are kept at bay. Now, I am not saying that there are zero weeds if you use this method. You are making holes where you are putting the ground staples through and where you are planting your seedlings or seeds. Also, it is just about impossible to get it tight to all the edging. So naturally weeds will peek through at these spots. When we just mounded our dirt, we did not have problems at the sides. It is still a whole lot less labor intensive than weeding an entire garden.
  • Yields will be higher, and plants will start producing earlier. Some of this can be attributed to the light that is reflected off certain colors of the mulch.
  • Warmer soil. The plastic mulch will warm the soil in the garden. This leads to faster plant growth.
  • Nutrients will remain in the soil and not leach out due to excess rains.

What color is best?

There are several different colors of mulch available for different plants and climates.

      • White on black mulch – This has always been our choice as we are in the South. The white on top helps keep the soil cooler than a black on black mulch. This can decrease the soil temperature as much as 12 degrees F.

    • Red mulch – This is excellent for tomatoes and strawberries. Red light is reflected back to the plants. This is useful in increasing photosynthesis capabilities. This color will increase the soil temperature 4 to 6 degrees F.

    • Blue mulch – This is good for cucumbers, squash and melons. This will increase the soil temperature slightly more than the black.
    • Black mulch – This can be used for warm season and cool season crops. At a level of 2” to 6” the soil temperature will be increased 3 degrees to 5 degrees F.

  • Metallic mulch – This is thought to help control pests. It has been shown to reduce aphids and whiteflies. It is believed that the metallic sheen confuses the insects.

Installing plastic garden mulch

When it is planting time, you should work your soil as you normally would.

  • We use a small tiller and then level out our soil with a rake.
  • Set up your watering system and check it for leaks.
  • Roll out your mulch and secure it with ground staples and any other weights you may choose to use.
  • Plant

We have found a method of rolling out the mulch that works best for us. We place the roll at one end of the bed and place the good side up. We have one person on each side of the bed. We then roll it out about 10 feet. We then place our ground staples at approximately 18”. Then we just repeat until we reach the end of the row. Once we have placed enough ground staples for our rebar to fit we will place it over the top of the mulch on the edges. We have found that just rolling it out like this, a little bit at a time, allows us to put our mulch down even on windy days. The wind always seems to kick up in the Spring just as we are getting ready to put our mulch down. It never fails.

Plastic garden mulch is only good for one year. You will remove it and dispose of it once the season is over. You will be rotating your crops and will need different spacing of the holes next season.

We have always used ground cover in our walkways. This gives us a nice (almost) maintenance free garden. The ground cover will last 5 or 6 years even being walked on daily.

Conclusion

Plastic garden mulch is one of the best innovations for gardeners. It helps us keep a healthy, clean, high producing garden. I am glad that I found it when I did. I would never go back to gardening without it. Share your experiences with us in the comments below.

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Which Polycarbonate Sheet is Best?

Which Polycarbonate Sheet is Best?

Polycarbonate Sheets

Which polycarbonate sheet is best?

Polycarbonate sheets –

Which thickness, color, etc should I choose? This is a question that I get asked regularly. It was not so difficult in 1993 when we started dealing with polycarbonate. We had a local business where we sold and installed at that time. We were in the South, so all our projects were done with 8mm clear twinwall. There really were only 2 options readily available at that time – 8mm twinwall and 16mm triplewall. Mostly the 8mm was used in warmer climates and 16mm was used in cooler climates. But all that has changed now.

Always be sure to use polycarbonate sheets that are UV protected one side for any outdoors project such as a greenhouse, patio cover, etc. That is what contributes to the longevity of the sheets.

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What sheets are available?

Today you can get polycarbonate sheets in 6mm (1/4”), 8mm (5/16”), 10mm (3/8”) 16mm (5/8”) and 25mm (1”). Sheets are available in clear, opal, bronze and specialty coatings. These specialty coatings provide properties such as diffused light. I will break it down more sheet by sheet.

What is the difference between the thicknesses?

The different thicknesses will have different properties such as light transmission, etc. But the difference is also in the amount of framing you will need under the sheets. The strength in your structure is really coming from the framing, not so much from the sheets.

You should be able to get a chart like the one below from the dealer you are working with. This will show you the purlin spacing in a rafter and purlin roof design. You will see that as the snow load goes up the frame spacing can be further apart for the thicker sheets.

framing spacing for polycarbonate sheets

Purlin Spacing for Polycarbonate Sheets

 

Also, the thicker the sheet and the more walls – the higher the R value or insulation factor. If you are in an area where heating costs are a concern you will want to get the highest R value for your budget. That is unless you do not plan on heating your greenhouse in the winter. Then the R value is not that much of a consideration.

What is the difference between the colors?

Clear sheets will have the most light transmission and are the choice for a greenhouse unless you are using a specialty sheet such as Polymatte, Polycoolite, Lexan Softlite or Polisoft. These preceding 4 named sheets all supply 100% light diffusion with a light transmission comparable to clear. With 100% light diffusion the light is spread so that it reaches all parts of the plant equally, even under the plant canopy. This leads to higher production and a healthier plant.

Opal and bronze sheets do not have enough light transmission for a greenhouse unless you are growing plants with low light requirements. They are better off being used for patio or pergola covers. Remember, if you are covering a pergola the sheets need at least a 1 on 12 roof pitch. You cannot lay them flat.

Which thickness should I use?

Now you not only need to consider the thickness you will also have the option of how many walls. A twinwall sheet has two sheets on the outside with a rib running straight between them. A triplewall sheet will have an interior wall running parallel to the two exterior sheets. Also, when you get into polycarbonate sheets with 5 or more walls you may sometimes have an X shaped configuration.

  • 6mm twinwall – This is an excellent choice for a patio cover, etc as you are not so worried about a higher R value on this project. It is also an excellent choice for a greenhouse in a warmer climate. Although I prefer the 8mm twinwall as it typically has an anticondensate coating on it. This is a coating that allows condensation to sheet off rather than come off in droplets. Healthier plants are the result of this. But, if the budget does not permit the 8mm, the 6mm is your next best bet.
  • 8mm twinwall or triplewall – This is my choice for greenhouse glazing in a warm climate. It has the anticondensate coating as previously mentioned and all the profiles are readily available for it. The 8mm triplewall will have a higher R value than the 8mm twinwall. It will be a comparable value to a 10mm twinwall sheet.
  • 10mm twinwall or triplewall – 10mm sheets do not require framing to be spaced as close as the 8mm sheets. So, if you are in a moderate climate with a small amount of snow this would be an option to consider. The triplewall sheets will have a higher R value than the twinwall sheets.
  • 16mm triplewall or 5 wall – These are both excellent options for greenhouses for cold weather climates with a heavier snow load. Remember to build your frame with appropriate spacing as per the chart above. The 5 wall will have a higher R value than the triplewall.
16mm 5 wall polycarbonate

16mm 5 wall polycarbonate

  • 25mm 3 wall – If you want to go even higher with the R value, this would be your choice. Please keep in mind though that typically you will have to use the aluminum profiles with this sheet. Polycarbonate profiles for 25mm are not readily available. The only real difference in the profiles is the look and the fact that the pricing will be higher for the aluminum. Just keep that in mind when you are looking at your budget.

Conclusion

Polycarbonate can be difficult to work with the first time you are using it. I think that most people tend to over think it some. There are a few basic installation rules that you must follow, but it is not all that complicated. There are a lot of options today and a lot of decisions to be made, more than when we started using it. Hopefully this breakdown will simplify this process for you. The biggest mistake is getting overwhelmed before you start and not getting your project done. So just take it step by step and enjoy your greenhouse when it is completed!

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Greenhouse Accessories – What do I really need?

Greenhouse Accessories – What do I really need?

Which greenhouse accessories do you need?

Which greenhouse accessories do you really need?

Greenhouse Accessories

Some people try to buy everything they can when they purchase their greenhouse. Others think that all they need is the greenhouse itself and they are ready to go. I find flaws in both ways of thinking. A greenhouse is a building – nothing more, nothing less. The greenhouse itself with contribute virtually nothing to the controlling of the environment. It will not heat itself or cool itself without the necessary components.

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Cooling the Greenhouse

 

Ventilation Systems

Some people believe that they will not need a ventilation system. This may be a correct assumption under some circumstances. They feel that they will not be using the greenhouse in the summer so they will not need this. Although I have heard my ventilation system run on a bright, sunny 60 degree day in the winter. I keep my thermostat set on 90 degrees.

I recommend getting the ventilation system at the same time as the greenhouse due to the fact it is installed directly in the walls. If you have a polycarbonate greenhouse it is easy enough to retrofit this at a later date by cutting the polycarbonate. But, if you have a glass greenhouse retrofitting is more difficult.

A ventilation system will consist of an exhaust fan which should be placed up high on one end, 1 or more intake shutters which should be placed down low on the opposite end and a thermostat. These systems should be appropriately sized for your greenhouse.

Of course if you don’t have electricity or want to use passive methods they are available also. There are also solar powered ventilation systems available at this time.

Passive cooling

Passive cooling can be done several different ways. Probably one of the simplest and least expensive ways is using a shade cloth. This can be placed on the inside or the outside of your greenhouse. This is simply like standing underneath a shade tree in the summer. It will help keep the intensity of the sun and the heat down in your greenhouse.

  • Shade cloth – While you don’t necessarily need to purchase the shade cloth at the same time as the greenhouse keep in mind that they are usually made for you as ordered and can take 2 – 3 weeks to receive. Don’t wait until the last moment to purchase this if you feel you will need it.
  • Roof vents and side vents – These are part of the structure, so they should be purchased and installed when building the greenhouse. Warm air rises so the roof vents will allow it to escape. The side vents add a chimney type effect drawing the air through the greenhouse and out the roof vents.
  • Roll up side curtains – If you are going to use these you should purchase them at the same time as the greenhouse. They can be retrofitted, but installing them when building the greenhouse is the simplest. They simply roll up and allow added ventilation for the greenhouse.

Heating the greenhouse

If you are purchasing the greenhouse in the fall and intend to use it for the winter you should definitely purchase this at the same time you get your greenhouse. The only exception to this is for someone who is not going to heat their greenhouse at all. This all depends on the crops you are growing and their needs.

Be sure to use a heater that is meant for a greenhouse as there is lots of humidity and water spraying inside. You can get these in natural gas, propane or electric.

Greenhouse Benches

Benches can be added at anytime since they are not attached to the greenhouse itself. Be sure to use a bench that is no more than 3’ wide so you can reach all of the plants to tend to them. If you are doing a center aisle and can work the bench from both sides you can use a 4’ wide bench.

Greenhouse Circulating Fan

This is the most often overlooked and most critical accessory for a healthy greenhouse. These should run 24/7. They mix the air and keep a more consistent temperature throughout the greenhouse and can reduce overall heating costs. A circulating fan helps to reduce the humidity in the plant canopy discouraging mildew and plant diseases. Carbon dioxide utilization, a necessity for plants, is improved. Carbon dioxide is used during photosynthesis along with water to be converted to sugar (food for the plant) and oxygen.

Greenhouse Lighting

Most greenhouse will have enough lighting for hobby greenhouses. If you are growing commercially and looking for expanded production, you may add these when building the greenhouse.

You may need these if you could not place your greenhouse in an area with enough natural lighting. I used HID lighting (but recommend LED lighting now)  in my greenhouse for supplemental lighting for my tomatoes in the winter. The daylight hours are just too short.

While lighting can be added at anytime if you know you will need them go ahead and purchase them at the same time you get your greenhouse. If not wait and watch your plants. They will let you know if they need extra light.

Misting or Watering Systems

I think this is something best left until you have the greenhouse together and see how the framing is. That will help you determine the layout of your watering system. We have always used a frost proof hydrant in our greenhouse so we don’t have any worries about freezing. The automatic system I prefer is an overhead misting system. This consists of tubing hanging from the greenhouse frame with emitters at specified placements. I then put this on a timer. But, another watering system may better fit your needs. Just be sure to keep all watering away from your heaters when setting up the system.

Max/Min thermometer

I think these are an important tool to have in your greenhouse. They let you know just what is going on. These thermometers register the highest temperature during the day and the lowest temperature during the night. That way you can really regulate the temperature where you want it. They are a small investment and I would recommend getting one when purchasing a greenhouse.

Conclusion

A greenhouse needs accessories to function properly and to maintain the proper climate for your growing needs. It has always been my belief that greenhouse growing is a learning curve for all of us. We all have a little bit different climate. We are all growing different crops or ornamentals with different needs. Don’t buy a greenhouse and load up on all the accessories available at once. Get the necessities and use your greenhouse for a while. Your plants will soon let you know if there is anything that they need. Don’t be overwhelmed by all of this. The worst that will happen is you may have to replace a plant or two. And don’t be fooled, this happens to all of us, even 40 plus year growers! Enjoy!

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Greenhouse Foundation vs Greenhouse Base vs Greenhouse Floor

Greenhouse Foundation vs Greenhouse Base vs Greenhouse Floor

greenhouse foundation vs base vs flooring

Greenhouse base vs foundation vs floor

Greenhouse Foundation vs Base vs Floor

It seems that there has always been a lot of confusion about what goes at the “bottom” of your greenhouse. A lot of people use these three terms interchangeably. This is not true at all. Each of these 3 items is a different component of a greenhouse.

The greenhouse foundation and base pretty much serve the same purpose. They are used to give a good strong substructure to place the greenhouse on. They also help tie the greenhouse to the ground.

A greenhouse floor is another item all together. It is basically like the floor in your house.

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Greenhouse Foundation

A greenhouse foundation will be built much like any foundation you are building for your home, a garage, a shed, etc. This will all depend on your location.

Many of us have freeze/ thaw cycles that cause the ground to heave and could potentially cause damage to our greenhouse frame and / or covering. In order to build this properly you must go below your frost line and pour a footer or build a pier type foundation with Sonotubes.  They have complete instructions on their website (sonotube.com) if you are not familiar with this type of construction.

If you are not sure of the proper level you need to dig down to you can contact your building codes department, or possibly a local contractor.

This is a good practice for any glass greenhouse, but you can build up to a 8 x 12 single glass greenhouse without a foundation. You really want to be sure to build  a proper foundation if you are building a double glass greenhouse and a larger single glass greenhouse.

Also, any polycarbonate greenhouse over 12′ x 16′ should have a foundation. A foundation is also a good idea anytime you are attaching a greenhouse to your home or building although a lot of people will use a base with smaller polycarbonate kits.

Greenhouse Base

These are available with some of the kits on the market today. There are also some polycarbonate greenhouse manufacturers who recommend this method. A greenhouse base will be the same size as the perimeter of your greenhouse.

A kit may have a steel base, or you may choose to build your own treated lumber base. It does not come with a floor and it does not go below ground typically. The greenhouse is tied to the base and the base is then anchored into the ground. This helps to stabilize the greenhouse and keep it from getting blown over in heavy winds.

You can build a base like this for a small single glass greenhouse (up to 8′ x 12′) or for a polycarbonate greenhouse up to 12′ x 16′. With some of the kits it also serves a double function. Some of the kits require this for the doors to open properly.

Greenhouse Floor

The greenhouse floor is quite simply what you walk on. There are a whole lot of options for this. Some will choose to do a concrete floor. If you are going to do this you must address drainage when pouring the floor. Also, I suggest using a heavy broom finish, as wet concrete can get slippery.

A second option is to put ground cover down on a leveled dirt surface. This is a UV protected polypropylene material. You may have seen this at some commercial greenhouses. It is the black fabric with green stripes where they have their liners set up. It is a heavy durable material.

You can go one step further and put sand or gravel over top of the ground cover. You can also put pavers down the middle for a nice walkway. The possibilities are endless.

Some people will choose to actually build their raised beds in the greenhouse. If you are doing this you would just use the ground cover or concrete between the beds.

I have had one customer who built an intricate paver pattern inside the entire greenhouse. This is great because it is beautiful, and it is excellent as far as drainage is concerned.

Paver Floor Greenhouse

Paver Floor Greenhouse

In Conclusion

Hopefully this will clear up some of the confusion on the differences between a greenhouse base, foundation and floor. You have spent a lot of time, money and studying to find the perfect greenhouse, so be sure to build it properly so it will last a good long time.

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Greenhouses vs High Tunnels vs Cold Frames

Greenhouses vs High Tunnels vs Cold Frames

Greenhouses vs Cold Frames vs High Tunnels

Differences between greenhouses, cold frames and high tunnels

Greenhouse vs a High Tunnel vs a Cold Frame

Greenhouses, High Tunnels, Cold Frames? What? Aren’t they all the same thing? Nope. Read through to see the differences and the similarities between these structures.

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Similarities

All of these structures consist of a frame and glazing material. They are all used to grow plants, be they vegetables, ornamentals, fruits, trees, etc.

Differences

The structural and architectural features of each of these structures will vary somewhat. The way in which they are used, for example, the temperature maintained in the structures, will vary a lot. The configurations of the buildings will also be somewhat different. Some are considered temporary, some are permanent.

Cold Frames

Well, this doesn’t help either. There are 2 different types of structures that are referred to as cold frames. First is this small, low to the ground frame with a cover that is used to protect plants in cooler weather.

The cold frame we are concerned with is as pictured below. It is low to the ground, usually between 14’ to 24’ wide. The lengths will vary. They are typically unheated with natural ventilation from opening the large doors at the ends. They will be in a half hoop configuration and typically covered with a single layer of polyfilm.

Cold Frame

Cold Frame

The reasoning behind the low height is that it will help to hold the heat in closer to the ground. They offer protection from frost for container trees, shrubs and perennials. They allow you to plant crops 3 – 5 weeks earlier in the spring and fall seasons. Cold frames can also be used to grow cool weather crops.

Many people will remove the polyfilm at the end of the season and use these as a shade structure by placing a shade cloth over the top of the frame. They are typically considered a temporary structure, but you should always check with your building codes department before building any structure.

High Tunnels

High Tunnel

High Tunnel

The high tunnels are much taller at the peak than a cold frame. They can also be much wider structures. They are also typically considered a temporary structure as they have no foundation. They are portable and can usually be added onto easily. Typically, these structures have no foundation or sidewalls. They are simply constructed using hoops or bows driven into the ground.

They are usually glazed with a single film and use natural passive cooling with methods such as roll up side curtains and opening the doors in the end wall. In fact, that is probably the one statement that sums up the difference between a greenhouse and a high tunnel the best.

A greenhouse uses active methods of climate control while a high tunnel uses passive methods. The operating costs of a high tunnel will be much lower than a greenhouse. Some people do install a ventilation system or heating system in their high tunnel. Sometimes it is necessary for the desired growing conditions of the crops planted.

Of course, there are differences in the framing and glazing as well. A high tunnel will typically have a pipe or pvc frame. It is usually covered in a single polyfilm. They usually have large openings at the ends for the entry of equipment such as small tractors.

The NRCS (National Resources Conservation Service, part of the USDA) has an initiative program that helps growers get partial funding for high tunnels. According to their website …

 While they may look like greenhouses, high tunnels are actually quite different. Greenhouses are usually constructed of glass and metal, with plants grown in pots above the ground. High tunnels are polyethylene, plastic or fabric covered hoop structures that can be assembled for a fraction of the cost, with plants grown in raised beds or grown directly in the ground.

Advantages of high tunnels are

  • The quality of plants and soil and increased
  • There is more control of the growing conditions than with outdoor growing
  • Extending the growing season
  • Cut back on pesticides and unwanted nutrients
  • Greater yield
  • Minimize energy usage

Greenhouses

Greenhouses are considered a permanent structure often requiring a building permit. They will have a proper foundation and be anchored securely to the ground. The foundation should be built according to the local codes in your area. If you are in an area that freezes you will need to build the foundation to the required depth to accommodate the freeze / thaw cycle.

The framing is usually a more permanent material such as aluminum or steel. Glazing can be single or double polyfilm, polycarbonate or glass.

The biggest difference between a greenhouse, cold frame and high tunnel is the systems that are put into place in a greenhouse. There will be ventilation systems, most requiring electricity. These may consist of roof vents or exhaust fans and shutters.

Greenhouses will also have heating systems such as a natural gas, propane or electric heaters.

Additional equipment you may find in a greenhouse would be lighting, evaporative cooling, timers and controllers, and advanced equipment to monitor parameters for the professional grower.

Greenhouses may be used year-round due to these systems that control the climate inside.

Typically, plants in a greenhouse are not grown in the ground, but in containers on benches, using hydroponic systems, or in raised beds.

Conclusion

We find that even though they look alike at first glance, there are considerable differences in the purposes of these three structures. While they are all used for growing, they are all used for growing different end products in different ways. But, they are all useful in their given purpose.

Just make sure that you do not buy a cold frame or high tunnel and expect it to function like a greenhouse. And remember in order for a greenhouse to function properly you must have the systems in place to get your climate where you need it to be.

Regardless of what crops and how you want to grow them go get a cold frame, greenhouse or high tunnel today and extend your growing season. Enjoy!

 

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