Building Plastic Tunnel System

Most vegetable gardens in the U.S. have two seasons - the spring season and the summer season.  By July there are empty spots in the garden from harvesting much of the spring crops such as broccoli and cabbage.  This garden will produce about 1 pound of fresh produce per square foot of growing area. 

By extending the growing season of your garden on both ends, early spring and fall, you can increase your productivity to 2 or 3 pounds per square foot in the same size garden.  It is not all that difficult but It does take some planning and preparation. 

 Plastic Tunnels Help Extend Growing Season

The plastic tunnel for this gardening system is made up of four flexible PVC supports set into the PVC foundations on the boxed bed.  Then a clear plastic cover is fashioned to lay over the tunnel supports creating a little greenhouse.  The plastic is held down by bricks.  The tunnel protects early spring plants and late fall plants from frost and wind damage.  It keeps the air temperature high enough for the plants to grow and helps the soil temperature stay high.

The Five Seasons Of The Most Productive Vegetable Garden

 Yes, five seasons.  You don't have to try to have all five in the first year, but consider these five seasons as a reasonable goal over two or three years.  With five seasons you are looking at growing 4 pounds of vegetables for every square foot of growing area.  A 200 square foot garden produces 800 pounds of vegetables; the neighbors will love you.

 Early Spring Season

In most gardens you begin harvesting early lettuce, maybe some spinach, and radishes in early June.  In the Early Spring Season, using the plastic tunnels, we can harvest vegetables as early as the first week of April.  Believe it or not, some of the early spring crop is planted in the late fall of the previous year.  

Spinach, Kale, early lettuce - plant in mid-October.  Cover seedlings with a one inch layer of straw mulch to get through the winter.  Rig the plastic tunnel in early March.  Spinach will be at harvest stage by early April

Swiss chard - Plant seeds in mid-November.  They will not germinate then but will germinate in very early spring, four to six weeks before you have Swiss chard planted in the spring.

This is only a partial list of vegetables that can be planted in late fall and come to harvest in early spring.  It is a trial and error process, but doesn't take a lot of time.

Normal Spring Season

Here you try to start seeds as early as is practical for your area. If a plastic tunnel has been in place for at least a month, usually the soil temperature will be ten degrees higher than outside the tunnel allowing to plant some vegetables two weeks earlier than usual.  When the outside soil temperature catches up you can remove the tunnel.  The ToolShed offers all the seed starting equipment you will need; click here. Generally, you can start seeds indoors 8 weeks before the seedlings can go out into the garden.  Here we are talking about cabbage, broccoli, cauliflower, and Swiss Chard to name a few. Push the seed start back a week and put the seedlings out in Wall's O Water a week or two before normal planting time.   Lettuce and spinach can be planted outside under a cold frame and get extra protection covering the plants with fleece at night.  

The key to success in the normal spring season is to be very observant of the soil temperature remembering that all vegetables need a certain soil temperature before being planted into the soil.  However, you can cheat using Wall's O Water which raises the soil temperature within the device.  

Main Summer Season

When people talk about a vegetable garden, this is the season they generally are referring to - the time for tomatoes, peppers, cucumbers, green beans, carrots, beets, and a gazillion zuchinis. You can start seeds indoors about 4 weeks before the last frost or you can buy your seedlings from the garden center.  Again the minimum soil temperature is the control.  Tomatoes should not go into the ground until the soil temperature is at least 65 degrees. 

Succession start now - As we discuss in another section, in order to have maximum productivity from our garden we don't want any bare soil anywhere in the garden from last frost to first frost.  Therefore, during this summer season, you will need to figure out what to replace the broccoli, cabbages, and kohlrabi plants with when they are harvested and removed from the garden.  You can plant seedlings or seeds, but you want to plant something. 

Fall Season

This is an easy season that most vegetable gardeners overlook.  The tomatoes, peppers, cucumbers, summer squash and pole beans produce food all the way to the first frost so there is the illusion that you have a productive vegetable garden in the fall months.  Not so.  There will be lots of vacant soil because most people do not use succession growing technques.  You can have fall cabbage, fall broccoli, and fall Swiss Chard.  You need to check the seed catalogs for varieties that work especially well in the fall.  You will start these plants in late June or early July. 

Late Fall Season

The late fall is a time for some of the tastiest and most nutritious vegetables.  One week before you expect the first frost you can erect your tunnel(s) again to protect plants for an extra month or two.  Kale is a wonderful vegetable that will produce right up to Thanksgiving.  Swiss chard replanted to replace the spring plants will also produce well past first frost.  The root crops, carrots, beets, and parsnips will be wonderful and fresh when left in the ground right up to Christmas.  Most of these crops are planted  early July when it is hot.  So special techniques are required to get those seedlings through the summer.  Shade cloth is a wonderful tool for this job.

So you see that your vegetable garden can be producing fresh food for your table from April up through Thanksgiving; almost 8 months of productive growing, mostly because you have little greenhouses for your garden called a plastic tunnel.  That is double the four months of production found in most vegetable gardens. 

Building A Tunnel System On Boxed Raised Bed

The tunnel rests on four flexible PVC pipes about 8 feet long.  They are inserted into the PVC foundation on one side of the bed and then bent into a semi-circle as the other end is placed in the PVC foundation opposite on the bed. 

There are two kinds of plastic covers for the tunnel; the end panel (2) and the middle panel.  The plastic sheeting is attached to furring strips.  String is attached to each end of the tunnel about half way down from the top to give support to the plastic panels.  As the finished panel are laid over the ribs of the tunnel, the furring strips are held down by placing two or three bricks on each one.  Ventilation cuts are made on each side of the tunnel; this is very important. The two end piece need to be folded to keep the neat shape of the tunnel.  You can get into the tunnel to work on plants simply by lifting up the side of one panel.  




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