Cold Frames and Low Tunnels

Cold Frames and Low Tunnels

Cold frames and low tunnels can be an economical way to extend your growing seasons and improve your garden.

It may seem a bit early, but fall and winter will be here before you know it.  It’s time to think about your fall and winter gardens and how to extend your growing season a few extra weeks.

If you are like us and garden primarily in raised beds, there are several options you can consider.  Modifying your raised beds to be used with cold frame covers or with low tunnel hoops is easy and can extend your fall and winter growing seasons as well as allow you to get plants in the ground earlier in the spring.

Modified Raised Beds.

Cold Frames and Low Tunnels

We have modified several of our raised beds so that we can use them as cold frames.  The modifications were easy for someone with access to basic power tools and a little bit of skill. 

Our raised beds are built of 2 x 6 dimension lumber.  I buy it out of the cull bins at the local big box stores.  If you aren’t familiar with cull bins, you should be.  They are great places to scavenge for low prices on lumber that is usually not serviceable in the building industry but can be used in the garden quite readily. 

My method of converting a raised bed to be used as a cold frame is to add one or two courses of sideboards to one side, add an angle cut board to the ends, and build a frame of 2 x 4’s over which I can stretch clear plastic to make the cover. 

Cold Frames and Low Tunnels

This photo clearly shows the additional 2 x 8 that I added to the back of the grow bed that sits on the east side of our greenhouse.  You can also see the slanting board that I added to the end.  Resting on top is the 2 x 4-inch frame cover with the plastic installed.  I staple the plastic to the frame and then screw battens over the plastic to help keep in intact and prevent the plastic from pulling away from the stapled.

Considerations for Modified Beds

These types of overs work well for us and allow us to stretch our growing season well into the winter months and to move our transplants earlier, giving us a head start on the spring growing season.

The one drawback is the height of this modification at the front.  Your plants must be short or very young.  Once your transplants start to gain height, they begin to push against the plastic which can impede their development. 

The operation is simple.  When the weather is warm and pleasant, we prop the cold frame cover in the up position with a piece of lumber.   In the evenings or when the weather is inclement, we lay the covers down.

You do need to monitor your moisture levels.  The covers will prevent any naturally occurring moisture from reaching your plants.   With the plastic on, the rain doesn’t get to the beds.

Low Tunnels on Raised Beds

Cold Frames and Low Tunnels

We also cover some of our grow beds with low tunnels hoops and plastic.  On these beds, I added a length of 2×4 to the top of each bed, laid on the wide side.   My wife likes this addition for several reasons but I think mostly because it is more comfortable sitting while she is weeding, planting or harvesting.

With the 2×4 fixed to the top of the grow bed, I drilled a ¾ inch hole at an angle on the inside edge of the 2/4.   Our hoops are ½ inch PVC pipe cut to 5-foot lengths.  Our raised beds are 4 foot wide, so a 5 ft length of PVC makes a nice bow that gives is some height in the middle of the bed.   The ½ PVC is easy to bend and fits nicely into the ¾ inch holes.

COld Frames and Low Tunnels

As you can see in the picture, I drilled my holes about every 2 feet along the sides and on the ends of the growbed.  2-foot spacing gives you room to work between them and provides plenty of support for the plastic which is important if you expect any snow load.  The last thing you want is your frame collapsing onto your plants during a freak early snow event.

To cover the growbed, we pull the plastic over the hoops and use landscape bricks to hold it in place.  This simple solution allows us to pull the cover off quickly during warmer days and easily replace it when the weather threatens or in the evenings.

The materials for these projects are easily sourced at your local big box home improvement store.   The plastic we use for these covers is 6 mil painters plastic.  It is relatively inexpensive, easy to work with, and does an admirable job at protecting the plants.

These types of DIY covers and frames are easy to build and install and can open a whole new set of options for your fall, winter, and early spring gardens. 

Good for the Garden

Many vegetable plants will thrive deep into the winter with just a little protection and care, allowing you to enjoy the benefits of your garden well into the winter months. Remember also, that your soil stays healthier when there are living roots available to nourish the bacteria and fungi in the soil biome.

Get busy and start thinking about fall and winter gardening in a different light.

Links and Resources

For more information about organic gardening, lifestyles, and living, visit our website at West Texas Organic Gardening.

If you found the information here helpful, you might also find these articles on our website of interest.

Building Raised Beds

Winter Soil Building

Winter Pest Control

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