It’s Settled: Brassicas Do Not Get Significantly Sweeter After a Frost
Lot's of hunters think deer crush kale and relish radishes now because the starches in brassicas turn to sugars in cold weather. But this University of Tennessee study proves otherwise
You’ve probably heard that brassicas get sweeter after a frost. Me, too. In fact, I’m sure I’ve even said it in the past. Like a lot of deer hunters, I’ve seen whitetails absolutely pound brassica plots when cold weather sets in. There’s one plot of radishes and turnips on my lease that my buddies and I like to hunt after a good winter storm. From the blind, it’s hard to see deer enter the plot, so the first thing you notice usually isn’t the body of a whitetail but the root of radish or turnip swaying back and forth through the air. Then you pull your binocular up and sure enough, there’s a deer on the other end.
Whitetails are so sure to hammer brassicas in some areas when cold weather hits, and the reaction is so immediate, that there has to be a specific reason for it, right? And it isn’t just deer hunters who think that the starches in root vegetables turn to sugars after a frost or two. Gardeners have forever advised against harvesting them too soon. On the other hand, in recent years, I’ve had profession land managers tell me just the opposite—that brassicas don’t get significantly sweeter with a frost and that this is only an old wive’s tale.
So who’s right? What’s the truth?
New Study Tests Whether Brassicas’ Starches Turn to Sugars After Frosts
That’s what University of Tennessee graduate students Mark Turner and Bonner Powell (under the direction of Dr. Craig Harper) set out to learn recently by collecting and testing brassica samples from food plots in North Carolina and Tennessee before a frost had occurred in early November and again after several frosts had taken place in early December. Mark Turner published the results of that study in an article on the National Deer Association’s website this week, including this chart breaking down the results.
As to the main question of whether the starches in their samples turned to sugars after several frosts, Turner had this to say: “We did record slightly elevated sugar concentrations in kale, radish, and turnip leaves following frost, but starch levels also were slightly higher after frost in kale and radish leaves, indicating starch levels do not drop after frost. Additionally, there was no change in the sugar levels of radish and turnip taproots following frost. Sugar levels in both were relatively high before and after frost.”
The researchers also tested for crude protein, acid detergent fiber (ADF), and sulfur levels, as these too can affect palatability and digestibility, but none were significantly or uniformly changed. The bottom line, as Turner put it, is this: “No, brassicas do not get sweeter after frost.”
Does that mean you should spend any less time hunting over brassicas in cold weather or planting them for late-season hunting. Of course, not. Whitetails will go on hammering your turnips and radishes and beets when the mercury drops, but most likely it’s because these plants simply provide a highly digestible source of carbs and fats, as well as protein, at a time when they need them most. The only thing hunters need to change is believing that it’s because the plants are significantly sweeter.