Ice for lettuce seed; Mistake in my book; fall sowings

The photo above shows our strategy for germinating lettuce seed when the soil is too hot (above about 84F (29C). First I shade the soil for several days to cool it, and I keep it moist. Then I sow late in the day, cover the seeds with soil, tamp down, water with fresh-drawn cold water, set out ice cubes along the rows, cover with shadecloth and retire for a relaxing cup of tea. One tray of ice cubes is enough for a 4ft (1.2 m) row.

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I just got this email pointing out a mistake in Sustainable Market Farming. So get a red pen and fix your copy today! An observant reader said:

“Hi! I just read the section on potatoes in your book “Sustainable Market Farming” and was a bit confused because of the yield numbers on page 376. You write “Yields are likely to be 150 lbs/ac (168 kg/ha); 200 lbs/ac (224 kg/ha) is a good yield”.

I’m currently working on a farm where we get 200-250kg of potatoes from one 100m row, that’s the number you say is a good yield per hectare… And I don’t even think our yield is particularly good, because there was a lot of damage in the potatoes (green ones, wireworm, slugs, scab). So I guess your numbers are just a mistake?”

Yes, my mistake indeed! On page 45, I have the (better!) info that potatoes can yield at least 110 pounds/100 feet, or 49.9 kg/30m. I think I probably meant to write on page 376, that a low yield could be 150 pounds/100ft, which is equivalent to 11 tons/acre. In the metric system, that’s 223 kg/100m, or 24.4 tons/ha. Other sources suggest average yields could be almost twice this. And good yields, even 4 times the low numbers.

So it should say

“Yields are likely to be 11 tons/ac (24.4 tons/ha); 22 tons/ac (48.8 tons/ha) is a good yield”

That’s US tons of 2000 pounds, metric tons of 1000 kg. Or for a smaller scale, probably closer to what most of us are growing,

“Yields are likely to be 150 lbs/100ft (223 kg/100m); 200 lbs/100 ft (300 kg/100m) is a good yield”

I hope I’ve got all the conversions right. Let me know if I haven’t!

While researching yield figures, I found an interesting publication, The Potato Association of America, Commercial Potato Production in North America 2010.

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The month of August is when we establish crops that will feed us in the fall and winter.

We sowed carrots August 8 and are now hoeing them and hand-weeding and thinning. We flamed these carrots on day 4 after sowing, because we have found that carrots can emerge on day 5 when it is as warm it can be in August. The idea is to flame the beds the day before the carrots are due to emerge. Flame-weeding is a great way to get rid of millions of fast-growing weeds and leave the field free for the slow-growing carrots. We still have to weed and thin once or twice as the carrots (and weeds) grow, but it is much easier to see the carrots, and they grow better if the first flush of weeds has been flamed off.

Some years all goes smoothly, and some years not! This year we had two snags. One is that the carrots were mistakenly sowed an inch deep, instead of near the surface. Of course, this delays emergence, so by the time the carrots made it through that inch of soil, many new weeds had sprung up too. The second challenge was that our well pump has not been working right, and we have not had enough irrigation water. And until this past week, we had a very hot dry spell.

But now we are making forward progress. Twin Oaks can eat 30+ bags (50 lbs, 23 kg each) of carrots during the winter, so we try really hard to grow a big crop of fall carrots.

We sowed cucumbers 8/2 and they are up well. The 8/5 beans look very good indeed.

The first two beds of kale (sowed 8/8) came up well, thanks to diligent hand-watering. The second two (8/12) are also up, and it’s just a day too soon to say the third (8/17) are just as good. Sowing two beds of kale at a time is a good strategy allowing us to focus the hand watering on the not-yet-emerged beds, for best success. We try to have the pairs of beds very near each other, to make dragging the hoses easier. This year we even sowed some back-up flats of kale, because last year’s kale had such a hard time getting established. (It might have been cutworms or grasshoppers).

The squash was sown a little late this year (8/10 rather than 8/5) but there is still hope. Our average first frost is 10/20 (our average over the last 13 years), so with a 54 days to maturity (from direct seeding) squash like Zephyr, we reckon on sowing 68 days before that first frost – or more to allow for seasonal cooling and even an early frost. That’s 8/13 absolute last date. We’ll use rowcover once fall cools down, but we do hope for a decent yield before the plants get killed.

Our fall turnips are doing well. We sowed them 8/7 under insect netting. here you see a row of radishes squeezed in at the edge of the bed. We often do this with radishes because we only want 90ft (27 m) at once. Kale beds are another place we sometimes sow radishes. Because radishes grow so fast, they will be gone by the time the slower, bigger crops need the space. And because they don’t get tall, they can be at the edge of the beds without getting in our way as we walk along.