Comparing organic potato yields in a home garden: cut potatoes vs. single drops

This year, as I planned to plant about 250 sf of seed potatoes, I decided to try cutting potatoes and planting pieces, instead of my usual “single-drop” method of simply planting whole small (less than egg-sized) potatoes.  Here are the results, using Kennebec potatoes.

The plants themselves were noticeably different in size.  This bed has two rows of cut potatoes and seven rows of single drops.  All rows have 10 plants. The single drops were planted at two different spacings between rows: 9″ and 12″.

Potatoes

Cut potatoes (and sprouting oat straw) on the left; single drops on the right. Planted May 20; photo taken June 26.

Curiously, early season harvests showed the cut potatoes far outproducing the single drops.  More energy going into roots and less into big, leafy plants, maybe? I didn’t weigh these, but I think I got 50-100% more potatoes per plant from the cut potatoes in the early season.

On Sept. 19th, I harvested two full rows. Each row now had 9 plants, as I’d robbed one plant per row earlier.  Here’s the difference:

Potato harvests

Harvests from equal areas of single drops (left) and cut potatoes (right).

The single-drops produced nearly twice as many potatoes (27lb vs 14.5 lb), and the potatoes were larger. (By the way, does anyone know what causes “double” potatoes? Nearly all my potatoes this year look like two or more potatoes fused together, or two lobes connected by a thick neck, like a peanut shell.) Neither technique had many marble-sized potatoes, as I had last year.

The “wide-space” row yielded 15 lb per row vs 27 lb. for the “normal” row. Keep in mind that the wide spacing was only wider east-west; north-south, these plants were spaced the same as all other rows.

Why this difference? I’ve read that in some climates, spreading plants apart makes more nutrients available to each plant, and each plant produces more.  This does not seem to be the case in my garden. Possible reasons:

  • My garden has very deep, rich soil with lots of organic matter; plants aren’t competing for soil nutrients or water, even when close together.
  • That normal row was on the edge of the bed, and its vines had a ton of room to spread on one side.
  • The soil might have been richer on the single-drop side.  That side of the bed was build over last year’s sheet mulched bed – the cut potato end of the bed had proportionally more purchased soil and less composted manure. The wide-spaced potatoes were between the single drops and the cut potatoes.
  • The cut-potato end of the bed was less shielded from sun and drying.

So perhaps next year, I’ll try super-duper wide spacing, more like the suggestions for row potatoes instead of biointensive spacing.  If I can plant half the number of plants and get the same harvest, I’ll save a lot of money on seed potatoes, or need to save a lot fewer of my own from year to year.

Final harvest from this bed was in the neighborhood of  130lb or 1.3 lb per square foot.  I”m pretty happy with that! In comparison, the 28sf plot of Superiors I planted April 23 only yielded about 0.8 lb per square foot and didn’t actually come in that much earlier than the rest of the potatoes.  I still have to harvest the Yellow Finns that went in on April 29th.

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2 Comments

  1. Anonymous said,

    January 21, 2013 at 11:06 pm

    double potatoes are from your watering or a heavy rain that caused a second growth.

    • Emily said,

      January 23, 2013 at 9:45 am

      That would make sense given that year’s precipitation patterns. Thanks!


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