Over the past few weeks, we have discussed the weather and the various ways it influences the vegetables in the field. In this week’s segment, we shall attempt to shed light on the surprising phenomenon we encountered this year with our autumn potatoes. (And why are they coined “autumn” when winter is here full blast?)
In Israel, potatoes are grown in two seasons: the autumn seeding, September-October, ripening and harvested from December to April, and those seeded from January-February, ripening and picked during May and June. The rest of the year here, we eat spring potatoes from cold storage. The potatoes seeded in autumn are called “autumn potatoes,” and those picked in springtime are, of course, “spring potatoes.”
Potatoes are tubers (not roots!). If the roots are the foundations of the house anchoring it to the earth, the tubers are the basement, where important things are stored for a time-of-need. The tubers are actually a segment, or several segments, of the stem, used for accumulation – a type of storage bin for important nutrients (except water). And as such, the tubers are usually thick, round and bereft of the stem-color-green attained from chlorophyll. The base of the tuber shoots out roots, while its top sends stems, branches and leaves upward. This is what it looks like:
As the tuber is in fact a subsoil stem, when it meets daylight, the chlorophyll begins to develop and turns the tuber green. This is not something we want to happen, which is why we make a little mound at the base of the stems to keep moisture in the roots that prevent the earth from cracking, and to protect the tubers from light. As the potatoes grow, we mound them once again to add some expansion space. Over the past few weeks, we inserted our pitchforks into the mounds to crumble them, extracting beautiful, fresh yellow potatoes. After extraction, a fresh tuber is in a comatose state due to its growth inhibitors. After a while, these substances subside and growth material develops, which makes the tuber bloom and sprout. In order to keep it asleep, we store it in dark, refrigerated conditions.
The potato is the winter representative of the Solanum tuberosums, who are cousins of the tomatoes, peppers and eggplants. Unlike these guys who enjoy the heat, the potato needs cool weather to yield tubers. High temperatures will make the plant grow tall and prominent, but with hardly any tubers underground, and sometimes none at all. A too-cold temperature will hinder the plant’s ability to grow. Small and weak, the tubers are left bereft of a source of energy for growth. Aggressive frost, too, can completely wipe out nice looking, elegant potato plants (speaking from painful experience). The ideal solution: moderate, cool weather – not too cold, not too hot. In short, an Israeli winter.
Except that this year, the winter was not moderate at all. Our dear potatoes, seeded at the end of September, faced challenging upheavals over the three to four months of their development. To refresh your memory, as we are currently soaked in puddles of rain and snow, here’s a short recap of the last few months: at the very end of autumn, in mid-November when our potatoes were just a month old, the field faced difficult days of dry heatwaves, dust winds and high temperatures. We had to generously irrigate in order for the potatoes to survive, but without overdoing it, as excess liquid can create diseases and be disastrous for the potatoes (just you wait and see…). Then again, extreme dryness is problematic. The strong east winds dried everything up in minutes, forcing us to find the balance between the contradictory needs of our vegetables.
Two weeks later, the rain came pouring and then continued to visit regularly, with nice sunny days in-between. As winter proceeded with more rainy days, the field gulped down nice quantities of water as cold temperatures reigned. The young potatoes indeed matured, but while we may have forgotten their complex heatwave-battling adolescence, some of them kept the memory in their flesh, in the form of cracks and rifts in the bulbs:
This rift happens to the bulbs when they grow in unstable conditions, usually an irregular supply of water, when dry days turn wet. The bulbs that grew in dry conditions are suddenly showered with water, spurring accelerated growth causing them to ‘explode’ and split. These rifts often start at the tip of the bulb and can expand horizontally. As the bulbs mature, the surface within the crack develops its own peeling, like that covering the rest of the bulb. Despite their cracked exterior, these potatoes are delicious. To avoid the task of getting out the mud within the crack, slice the potato along the crack and voila – problem solved.
Something else you might have noticed in some of the recent potatoes are dark spots at the core of the bulb. The potato can look great on the outside, but when sliced it displays strange-looking brown spots. This occurrence is called “internal browning” or “blackheart”, caused by a lack of oxygen in the center of the bulb. This oxygen deficiency creates suffocation, loss of breath and cell death. The damaged tissue blackens, and that is what you see at the center of the potato.
But why, do you ask, do our potatoes lack oxygen? Because they are buried deep in the saturated soil. The water in some parts of the bed doesn’t drain well. The deep ends of the bed are not sufficiently ventilated, creating little puddles that fill up the air pores in the soil, creating an oxygen shortage.
The center of the potato bore the brunt, as the oxygen was cut off at a later stage of its development. Being farthest from the surface, the core got the least oxygen, unlike the external parts of the bulbs which received sufficient air and grew well. The damage only affected the central inner parts, which is why the spots appear on the inside. Thanks to the low temperatures slowing down their breath, the situation wasn’t that bad. Things could be much worse if the bulbs are flooded or their oxygen is cut off at high temperatures. It’s important to understand that the darker parts do not indicate rotting or a disease. Even the potato parts that aren’t necessarily attractive are good for use.
These two phenomena are interesting because these are physiological problems, i.e., not caused by an insect, contamination or fungus, but rather by uncomfortable conditions, be it weather or the state of the soil. The potatoes respond to this stress by a change in shape and color. Of course, we cannot control the weather, but we try to do everything in our power to improve the conditions for our potatoes as they develop and grow.
Here’s where we come full circle: Remember how careful we were not to over-irrigate the potatoes during the heatwaves? Well, now you know why. Too much water will cause this problem (and others), too little water causes other problems, thus the game of quantities is a gentle dance of finding the right balance.
We are also constantly trying to improve soil ventilation in problematic areas. Our earth is valley Terra Rossa soil – heavy, thick soil that absorbs water and holds on tight. This is a great advantage, because the vital nutrients remain in the earth and don’t easily wash away (as in sandier soil). But in very rainy seasons when it’s challenging to keep the soil ventilated, we help out by adding high-quality compost that boosts the soil’s texture and ventilation. Every few seasons, we use a deep soil loosening plow that penetrates the earth without flipping and mixing the other layers (not recommended, as the upper 30 centimeters of the soil are the most fertile and it would be a pity to drive them deeper). The plow loosens the consolidated layers that hardened under those fertile 30 cm of soil, allowing better drainage during wintertime.
And yet, as you can see, in stormy seasons such as this one, there are major challenges which we are not always able to overcome. But we always strive to meet the challenges and improve.
Store potatoes in a cool, dark place.
As mentioned, potatoes turn green when they are exposed to light for any length of time. The green hue is the result of the chlorophyll, a natural plant pigment which is tasteless and harmless. The problem with green potatoes is that in the areas where the chlorophyll develops, an alkaloid called solanine can also develop, tasting bitter and toxic when consumed in large quantities. A greater concentration of solanine is found in the peeling or just below it, which is why older potatoes should be peeled. Cooking or steaming them reduces the solanine by 60-70%, as compared to a raw potato. The greening is caused by light, but also temperature, age, species and ripeness. Light potatoes turn green faster than red ones.
Potatoes keep quite well at a temperature between 8-28 degrees Celsius. A higher temperature will cause the tubers to sprout, wither and rot. At a lower temperature (in the refrigerator, or at 6 degrees and lower), the starch within the potato turns to sugar, giving the potatoes a sweetish taste and causing them to burn faster when fried.
Read this poetic post from the charming blog Shira Achila about potatoes and their potential, complete with a nice recipe (Hebrew). Enjoy!
May we have a wintery-but-moderate week, perfect potato weather. Wishing you a good week,
Alon and Bat Ami, Dror, Orin and the Chubeza team.
A reminder: The frigid cold has a profound effect on the cucumbers and tomatoes. It significantly slows down their growth…they simply don’t move. So this week there were not enough cucumbers to put in your boxes. We attempted to buy cucumbers from other organic growers, but unsurprisingly, with every single one, even those in the Arava, nothing is moving. Instead, we succeeded in buying sweet, yummy red bell peppers, which will arrive in your boxes in place of the cucumbers. We await the accelerated growth of our bright green friends.
Monday: Potatoes, cauliflower/slice of pumpkin, Swiss chard/kale/ broccoli greens/tatsoi, daikon/baby radishes/turnips, fresh onions, broccoli, sweet red peppers, tomatoes, carrots, celery/celeriac. Small boxes only: lettuce/baby greens (mesclun mix)
Large box, in addition: Jerusalem artichoke/garden or snow peas, cabbage/sweet potatoes, leeks/beets/parsley root, parsley/coriander/arugula/rakula.
FRUIT BOXES: Red apples, oranges/pomelit/lemons, clementinas, avocado, bananas.
Wednesday: Potatoes, cauliflower/cabbage/kohlrabi, Swiss chard/kale/broccoli greens/spinach, fresh onions, broccoli, sweet red peppers, tomatoes, carrots, celery/celeriac, red leaf lettuce, parsley/coriander/arugula/rakula.
Large box, in addition: Snow peas/sweet potatoes/slice of pumpkin, leeks/parsley root, daikon/baby radishes/turnips/beets, .
FRUIT BOXES: Red apples, oranges/pomelit, clementinas/lemons, avocado, bananas.