How to Build a Garden Cold Frame


A cold frame, as defined by the University of Missouri Extension, is a protected plant bed. It is a rectangular box with a back higher than the front and a slanted lid covering the top. The inside of a cold bed is anywhere from five to ten degrees higher than the outside, which improves the chances of certain plants surviving a cold spring night. A cold frame is also used to "harden" of seedlings that were started indoors by slowly introducing them to a colder weather without shocking their system.

Step 1

Measure out an area of 3 feet by 6 feet for the cold bed. This is the average size of a small garden, says the University of Missouri Extension.

Step 2

Dig out the measured area to a depth of 14 inches.

Step 3

Place 2 by 4 inch by 2 foot boards in the back corners of the excavated area, pounding them a few inches into the dirt.

Step 4

Place two 1 by 10 inch by 6 foot boards at the back of the cold bed and nail them to the 2 by 4 pieces set in the back corners.

Step 5

Place one 2 by 4 inch by 2 foot piece of lumber in each of the front corners of the excavated area and pound into the dirt.

Step 6

Place a 1 by 10 inch by 3 foot piece of lumber on each side of the garden and nail it to the anchor pieces in the four corners.

Step 7

Cut two triangular pieces of wood to finish off the sides of the cold frame. The pieces are 1 by 10 in size.

Step 8

Place a 3 foot by 6 foot glass sash on top of the cold frame. Glass sash pieces are available at most construction and gardening centers.

Step 9

Add soil and compost to the inside of the cold bed area and plant your garden.

Things You'll Need

  • Measuring tape
  • Shovel
  • 2 inch thick lumber


  • University of Maryland Extension: Hot Beds and Cold Frames for Starting Annual Plants
  • University of Missouri Extension: Building and Using Hot Beds and Cold Frames
Keywords: garden cold frame, cold frame construction, how-to cold frame

About this Author

Cleveland Van Cecil is a freelancer writer specializing in technology. He has been a freelance writer for three years and has published extensively on, writing articles on subjects as diverse as boat motors and hydroponic gardening. Van Cecil has a Bachelor of Arts in liberal arts from Baldwin-Wallace College.