Spring is fast approaching.
I can tell from the daffodils and crocuses coming up in the yard.
The seed catalogs piling up in the mail box.
And a note on my wife’s calendar saying simply, “chit”.
Chitting is a head start on the season.
There’s a lot to be said for growing potatoes in your home vegetable garden, despite the low cost of potatoes at the grocery store. They pretty much fend for themselves, with maybe a little watering in dry periods. They give a good yield of calories per square foot. Garden-fresh potatoes taste better than store-bought. And they keep well.
One drawback is that potatoes do not like the heat. Which you could have guessed, based on where most U.S. potatoes are grown.
Source: Potatopro.com
(Potato statistics are pleasingly archaic in nature. They are reckoned in “CWT”, that is, hundredweight or centum weight, a measure that goes back to medieval times. In the U.S. that’s 100 pounds. So Idaho produces around (120,000 x 1000 x 100) = 12 billion pounds of potatoes annually).
Note that the South is under-represented on that chart, to say the least. Plausibly a combination of hot summers and clay soils make it less-than-ideal for potato production.
Which is not to say that you can’t grow potatoes in the South. Virginia, for example, does have some commercial potato production. It appears to be almost exclusively on the Eastern Shore (reference), owing to the sandy soils there versus clay soils in much of the rest of the state. In a good year, Virginia will produce 200,000 pounds of potatoes, or about 0.002% the amount grown in Idaho.
In any case, based on what I’ve read, potatoes stop setting new tubers once nighttime lows exceed 55 F. In my area, that means any potatoes you’re hoping to harvest have to be set before late May/early June. Nighttime lows are typically in the 60’s F in June. Daytime temperatures in the high 90’s F will kill them outright.
The upshot of all this, in practical terms, is that if you want to grow potatoes in Virginia, you should try to get them growing as early as possible.
In this area, the traditional or folklore date for planting potatoes is St. Patrick’s Day, March 17. More scientifically, typical advice is to plant potatoes two to four weeks before expected last frost date. So, depending on which source I use, which percentile of the last 30 year’s frost experience to take as my guide for last frost date, and adjusting for windage and range, I make that out to be somewhere in mid-April. Subtracting four weeks brings me to mid-March as the correct planting date for potatoes. Or, in round numbers, St. Patrick’s Day.
Nice when folklore and science agree. But clearly that agreement won’t hold up in other climates.
Which brings me to chitting. For those unfamiliar with the term, to chit a potato is to sprout it. Chitting is not necessary. You can plant pieces of un-sprouted potato, and they’ll grow OK. But chitting potatoes before planting them has a couple of advantages.
First it plausibly gives you a head-start on growing them. Once they’ve sprouted, they’ve broken dormancy and are ready to grow. All other things equal, for a given planting date, you ought to be able to harvest chitted potatoes earlier than ones that were planted with no sprouts. The most common figure I see is “up to” two weeks earlier. But I see no hard data to support that.
Second, it allows you to be sure that your potatoes will, in fact, sprout. This is an important factor to me, see below.
It takes about four to six weeks for a potato to chit. Which means that if I want to plant them mid-march, I have to start chitting them now.
There’s not a lot of effort involved. Recommendations vary, but the typical advice is to sit your potatoes out somewhere, around room temperature, where they can get indirect light. (Others say a cool-but-frost-free location, instead of room temperature).
And wait. That’s it.
It’s one of those things where the whole trick to it is to remember to do it. Because those spuds ain’t gonna chit themselves.
Hence the calendar entry. Otherwise I’d never think of it. We’re probably two-and-a-half months from the time the very first potato shoots will break the ground.
Avoiding dud spuds: Using grocery-store potatoes as seed potatoes
If you plant un-chitted potatoes, in cold soil, it seems to take forever before the potato shoots break the surface. I see references of two-to-three weeks.
If, by chance, you get a batch of potatoes that won’t grow, that means you sit around for about a month, checking for sprouts. And only after a month is up can you conclude that your spuds are duds. Which means you’re now a month late getting your potatoes in. Which, in the South, means you’re going to end up trying to grow potatoes in hot weather. Which is inadvisable.
The first year I grew potatoes, I diligently paid a premium price for mail-order seed potatoes. Not only was the order delayed, but they all turned out to be duds. Plausibly, they got cooked in shipment or something. Whatever the reason, it was a total failure.
I ended up buying and planting farmers’-market potatoes that year. Just on a hunch that they wouldn’t have been treated with anything. And that worked. I had an OK crop of potatoes despite the complete failure of my seed potatoes to grow.
(FYI, as far as I can tell, seed potatoes are simply potatoes that are certified to be (nearly) disease (virus) free. I think in some instances, they may be certified to be true-to-type (no genetic drift). They are otherwise just regular old potatoes, same as you would buy in the store.)
Which brings me to the topic of growing your potatoes using grocery-store potatoes as your seed potatoes.
You will read pretty much every conceivable opinion as to whether or not you can, and whether or not you should. Whether or not it is illegal to do so, at least in some areas. What risks you incur by this practice. What risks you impose on others by this practice.
I’m just going to blow off the whole discussion of the risks of using grocery-store potatoes as seed potatoes. Mainly, you might get potatoes that carry a heavy load of some potato virus. Those might not just kill our plants, but might render your soil unusable for potato production for years. And those might spread to others.
I think those issues are far more relevant to home growers located near the big commercial growing areas. As a guy who grows a few tens of pounds of potatoes in his back yard, with the nearest commercial potato farms at least 100 miles away, and with nobody in my immediate area growing potatoes, I just don’t think I’m putting anyone at risk. And if the upshot of a mistake is that I won’t be able to grow potatoes for a while, in my garden plot, well, I’ll plant something else.
So, to me, the only question is, does this work? Can you plant grocery-store potatoes and have them grow?
And once again, you’ll read every opinion under the sun on that. Works fine. Doesn’t work at all. Gives stunted plants. Gives fine plants.
Last spring, I sorted through all of that and got to the bottom of it. You can read that in Post G22-004
In a nutshell, non-organic grocery store potatoes may (and typically are) be treated with a sprout inhibitor that’s so effective that it more-or-less destroys the potato’s ability to grow. If you buy a batch that have been treated that way, you’ll get no or stunted growth.
But that sprout inhibitor is banned for use on potatoes labeled as organic. Instead, sprout inhibitors on organic potatoes tend to be far less long-lived chemicals. (That is, they don’t work as well.)
As a result, organic grocery store potatoes should sprout and grow.
And this has been my experience. Of late, I just buy a couple of small bags of grocery store organic potatoes, chit them to be sure they’ll sprout, and plant them.
I’m still undecided on whether to try growing these using a no-dig method (Post #1073). Around here, for what I have to pay for a bale of straw, the purchase price of the straw exceeds the market value of the potatoes. But it sure is convenient. And the resulting potatoes surely nice and clean.
In any case, I have six weeks to decide that.
