Finally! Here’s what I think of as the indoor and field green difference in transplant leaves—at times hard to capture with the point-and-shoot. It happens for most transplanted seedlings. Their leaves grow, even quite massively, but their color remains…pale. And then a new set of leaves eventually appears that I call with satisfaction deep field green. It’s satisfying because to me it’s a signal that the plant has fully connected and is hunkering down for the growth it was built for, mainlined directly into the planet and the weather, for better or for worse. Transplant, successful. There’s no doubt biological truth to that, but it’s not a comment on some scientific mechanism, it’s just a feeling! :)
winter squash
Plants just wanna have sun
These winter squash are looking a little pale and thin, with those deprived-looking almost lime green leaves. No wonder, to go along with all the rain, most of the last few days have been cloudy. The garden veg really aren’t demanding. All they want is decently fertile soil—composted cow manure and a handful of alfalfa pellets will handle that—ample water, warm but not searing temperatures, and sun. Also, not being devoured by animals, insects or disease, or smashed to tatters by golf ball-sized hail, of course. This season so far, all conditions met. Except for the sun. The forecast continues cloudy with chance of rain for the next week. If that holds up, no rich, deep green leaves and satisfyingly sudden growth spurts for a while.
Peering down a rabbit hole
Not a literal rabbit hole, instead, the one that I encountered when just for fun I looked into sunburned leaf damage, like what appeared today on a single squash leaf. Sunscald during hardening off isn’t what you’re aiming for, but it happens and it’s never been a big deal. So long as the seedlings are well-watered and the roots aren’t getting cooked in their containers, they’ll be fine has been my experience. Still, since only one leaf among around three dozen squash and melon plants got burned, after several full days in the sun, and yesterday half overcast, I took a mild interest—if I was a lot busier, with hundreds or thousands of seedlings on the go, and everything else looked fine, it wouldn’t get a second thought. Odd one-offs happen all the time.
A bunch of reading and skimming of farm and garden blog posts, university agricultural extension papers, science mag articles, and scientific studies, and no answers. The sunburn itself seemed unusual, especially after a half-cloudy day. Of course, our SPF sunscreen-and-skin cancer training has told us that UV is still strong on cloudy days, but why did only one leaf get so toasted?
Then I discovered the UV spike. Not so widely written about, not as confidently stated as ~80% of UV makes it through clouds, but a real thing. When certain types of cloud pass in front of the sun, like perhaps the fluffy cumulus ones that floated by most of yesterday, the fringes of said clouds can act as a magnifying lens or filter that focuses and directs UV straight down, resulting in an intensity spike of maybe 25%. Could it be that one big early leaf hadn’t been shaded by the others on previous days and gotten more exposure and hidden damage, and just couldn’t take a day of high-powered UV micro-blasts, a few seconds each as the sun disappeared and reemerged, over and over. Hmm, that sounds maybe fairly reasonable…
Soon after, I lost interest—WHY would I want this explained? I could think of no good reason. I’ve found with tiny farming that learning is continuous and great, but what you choose to take in is also critical, sucking up everything is a waste of attention. The one burned leaf isn’t a mystery, it just clearly happened. And unless more similarly unusual things appear, I’m not particularly curious. The real thing to remember: harden off, a couple hours max outdoors the first day, and keep them well-watered and not boiling in their pots! When they get into the real ground, small ups and downs along the way will be forgotten, they’ll spread their roots and do just fine. Conditions in the field being favorable, of course!
Thigmomorphogenesis
Squash seedlings in a stiff breeze—gale-force wind would’ve made for a more dramatic image, but thankfully not. This bending and fluttering of leaves is another benefit, besides the sun, of taking indoor-started seedlings out into the real world.
Movement, like blowing in the wind, triggers the catchily named thigmomorphogenesis process in plants, where they dramatically toughen up after getting a little pushed around. It could be wind, a pummeling rain, animals or hands brushing by or moving them about. Makes perfect sense for them to armor up.
I’m not particularly into the details of how they change, develop sturdier stems and whatnot—tougher seems to sum it up just fine—but it’s good to know about (I used to use an oscillating fan in winter). And I really like the term. For most of my life, my casual thought was that knowing everything would be cool, kind of like AI tries to today. At one point, though, conveniently marked by a certain blog post, my thinking flipped to often wanting to know less. Not cheering for ignorance, just comfortably sticking with what’s necessary for the moment. So, thigmomorphogenesis—long, unwieldy, yet surprisingly easy to pronounce after a couple of tries!
Winter squash green
Broad, fast-spreading, richly green winter squash leaves, especially in their first few weeks, are kind of the emeralds of the vegetable patch. They’re poster plants for healthy garden growth. Unfortunately, that charm is hidden under row cover until they get well-established, to protect them from cucumber beetles. At flowering time, the cover comes off so bees can feed and collect pollen, and pollinate in passing all those future butternut and acorn squash. Here, with the cover pulled back for hand watering and a bit of weeding, you can see how squash do a great job of self-weeding by creating lots of shadow that keeps the competition down!
Winter squash spreading
Even with little sun, the winter squash won’t be kept down. What it likes to do is spread far and wide: huge leaves and vigorous vines snaking out all over the place. The big sprawl is just kicking in, flowering is underway, and tiny green baby (butternut) squash can already be found tucked away in there.
Squash to the field
Transplanted butternut squash seem to be doing fine in the great outdoors. The row cover will protect them from the fairly cucumber beetles, until they’re big enough not to be bothered. The beetles eat the plants and can also pass on bacterial wilt (I’ve experienced hungry cucumber beetles, but luckily so far, no wilt). This rock cover is medium weight, thick enough that it’s easy to handle without tearing and can be reused, and thin enough that it lets 85% of the sunlight through. A small tradeoff for no chemicals!