How to Build A Potato Box

Potatoes are cool season crops, which means you want to get them in the ground early.  The rule of thumb here in Kansas City is that they should be in the ground by St. Patrick's Day at the latest (for the early variety) or the last weekend in April (for the late variety).  Really, if you plant anytime between the beginning of March and the first weekend of May, you should be fine here in zone 6.

My original plan was to plant only a late season variety called Yellow Finn, which does well growing vertically in bins, garbage cans or other containers.  It also keeps better than Yukon Gold or Russets.  But, since J. says we have Russets sprouting in the basement, I may find some space to try those in hills as well. 

With all the nice weather yesterday and some idle time on our hands, J. and I decided to get those potato boxes built and off the "to do" list so that we'll be ready when the seed potatoes get here.  The hardest part about this project was picking the lumber, and this is something that you can easily do even if you're not Bob Villa. 

Materials Needed for the Potato Box

The concept behind the potato box is that you start with a short box of anywhere from 10 to 12" high and then add additional rows of boards all the way around and cover the plants with more dirt as they grow.  It's a great way to grow alot of potatoes in a limited space and, in many cases, it increases the yield over 200% over that of hilling them in a garden bed.
Let's get started building our box.  For each box, you'll need the following:

• (4) 2" x 2" x 36" corner posts that the boards will be screwed to
• (6) 2" x 6" x 8' boards
• (96) 2 1/2" wood screws (I prefer stainless so they don't leave black streaks and won't rust)

You can use pine, cedar, redwood or pressure treated (if it's been treated with copper sulfate only, which isn't toxic).  J. and I decided on cedar for the corner posts because it is very slow to rot even in direct contact with soil.  However, cedar is REALLY expensive.  The 48" corner posts are $3.48 each at Lowe's.  To offset the cost, we went with cedar fence pickets for the boards rather than the 2" x 6"s.  Also, we decided to spread the cost out a little bit and only purchased enough pickets to get the boxes started.  The pickets are 71" long, so we got 2 sides of a box out of each picket. 


Cedar 2" x 2" and pickets ready to be cut.



Step 1.  Cut the boards.  We used a chop saw because it makes this job alot easier.  Cut the corner posts to 33".  Then cut your boards.  If you're using 2" x 6" boards, you'll cut them into 12 21" lengths and 12 24" lengths.  The longer boards are 3" longer because they will overlap the shorter boards on the corners.

In my case, because we're using pickets, we went a little bigger.  After cutting the dog ears off the pickets, we had 71" to work with.  The pickets are 1/2" thick, so I needed for half my boards to be 1" longer (to allow a 1/2" overlap on both sides).  So we cut the pickets at 35", giving us one board at 35" and the other at 36".  Rinse and repeat until all the boards are cut. 



J. shows off his power tool skills while cutting our pickets.


Step 2.  Assemble the two short sides of the box.  Lay two of the posts out on your work surface.  Then place one of your shortest boards. at the bottom and line them up so that the outside of the board is lined up with the outside of the corner post (as shown in the picture).  Use a square to make sure everything is lined up properly.   Pre-drill two holes into the board and post and then secure with two screws.  Once you have the first board secured to both posts, add a second short board so that it's on top of the corner posts and butted up to the board that you just secured (this will give you a box surface that is approximately 11" tall.


It's a good idea to pre-drill the holes so that it doesn't split when you drive the screw into it!


Rinse and repeat with two more corner posts and short boards.  You should now have two completed sides:

Step 3.  Assemble the completed box.  Now turn your attention to the stack of longer boards, which we'll use to connect our two assembled sides.  Following the same steps, attach one of the longer boards to the other side of the corner post of one of your completed sections.  Make sure the outside of the longer board is even with the outside of the short board, forming a nice corner (as shown below).  You may need someone to hold the side while you get the first screw in. 


J. shows off his Milwaukee and his mad box-building skills. Meanwhile, I'm the human clamp (holding the side up).


Step 4.Place in your designated location and fill with dirt.   Loosen up the soil underneath it and make sure it's nice and level.  I also recommend putting down weed fabric in the bottom first to prevent having weeds growing up into your nice soil.  Fill with a mix of 2/3 garden soil and 1/3 compost. 


Here we are in the process of filling with garden soil and compost.


As the potato grows, we'll repeat the same steps above to add another level of boards and then dirt, taking care to never cover more than 1/3 of the new growth of the potato plant. At harvest time, we'll remove the boards from one side of the box, knock the dirt over and harvest the potatoes.

Now you're ready to plant those potatoes!  Stay tuned, as I'll be covering how to plant, as well as updates throughout the summer as our potatoes and potato box grow.

See this post featured and join me in finding out what other folks are up to over at this week's Country Garden Showcase, Barn Hop, and Country Homemaker Hop!