Why this picture?
Take a look at that temperature graph. Notice that it has a little “high bump” about the 12th to 16th, then a low trough from about the 19th – 27th; then reverts to warm from the 29th to now. (Yes, it’s been nice this las few days :-)
OK, I had started some seeds very early indoors. Some beans, squash, lettuces. Etc. I usually do this as it lets you get an “early jump” on the spring garden. Nominally our “last frost” is April 15th (as a conservative always OK to plant date) but usually it is some time in February or March. (Notice we didn’t get a frost problem on that graph).
So I typically start some “standards” in pots indoors.. First warm week, out they go into the garden. Typically, once things warm up, they stay warm and clear until next fall. At least, that’s been the pattern here in the 30 ish years I’ve lived here. Maybe the odd cold day or two, but not weeks in a row.
Well, this time is different…
I planted out in that warm bump in the middle of the month. Then the cold returned.
With it was incessant rain. A cold dank dark overcast kind of weather. More like winter than our usual Spring “dump of thunderstorm then sun”.
Into the Garden
So I got to watch my newly planted out garden cope with this. The first couple of warm days, things grew nicely. Then, under the cold dark overcast, many things just died (the squash, for example) and what didn’t die, just sat there. Even the Kale didn’t grow much. A little, but not thriving. The beans made sickly little spindly runners up the trellis, all the while having the two large main leaves get shriveled, nibbled by bugs, and just ‘worn’ by wind and weather. I thought I was going to lose them all. ( I did lose about 4 out of 8 plants).
Now, this week, the sun has returned. Things are thriving. Kale is jumping up, the beans have a nice deep rich green color to the leaves and the ‘skinny tiny leaf’ parts are filling in nicely. Plants are now growing fast enough to stay ahead of the bugs and birds, so less of a ‘moth eaten’ (literally!) look to the older leaves.
It is very clear to me that while the temperature was important, just as important was simply the level of brightness of the sun. Even the “cold tolerant” plants were sulking. Not from the cool, but from the shade.
To me, this says that we’ve missed the point on “The Dark Ages” famine. We’ve missed the point on the risks of another Iceland eruption. Yes, they make things cooler. But: You can’t just plant peas and kale instead of green beans and squash and stay fed. Not as an individual, nor as a country. My peas didn’t die in the cold, but they did just stay small and waited for the sun. They have roughly doubled now that I’ve got sun again. My radishes sprouted, and grew in a slow halting way; but now they are making good growth and starting to make edible roots. A plant needs to be thriving to have excess energy to store for our food, not just ‘hanging on’.
It’s All About The Clouds
No, we can do nothing to grow a decent crop if the cold comes with heavy clouds. As cold tends to do in the Dark Ages type of catastrophe. One day of sun produced more growth than 5 days of clouds and pouring rain. In addition to “degree days” as a maturity metric, we need a “sun days” as a productivity metric. (For what it’s worth, in 4 days of sun I’ve had 3 potted plants already dry out and start to get curled browned leaves… the sun cuts both ways if you forget to water…)
IMHO, knowing the global cloud cover is more important to knowing global food productivity than in presently believed. (and probably with it grain prices). We use “degree-days” to good effect party as it will have a very strong correlation with sun. BUt they quantity of crop still varies even with the same degree-days at maturity. Just like water, nitrogen, phosphorus, et.al.; sun is a limiting nutrient. Fall below the threshold, the rest doesn’t matter.
Once the other issues are met, it really is all about the clouds…
That, then, also means that we really are not in a position to predict global food productivity in any coming “climate change” as folks have substantially focused only on temperature and not on cloud / sunlight levels. To the extent we have volcanic haze or GCR clouds, there will be impacts we are not expecting just from the reduction of photons; even if the planetary heat budget stays the same.
Today, I’ve gone back under the clouds. Not too bad, yet. Still some sun under the edges. More like a typical Spring pattern. Sun and cloud taking turns. If tomorrow turns back into a solid, dark, cold deck, then my garden will stop growing. For now I’m hoping that even 3 or 4 hours of sun is enough for some ‘threshold’ of growth to be reached. That, and I’m going back for a bit of ‘sun time” with the bunnies and a cup of tea ;-) Yes, it’s time to “Make fun while the sun shines!”