Ask any seasoned food plotter why deer tend to eat brassicas later in the year and if I was a betting man I would almost guarantee they’ll tell you that brassicas become more sweet after a few frosts. Which ultimately leads to greater browse pressure later in the fall and into the winter. If you search this same question on the internet “Do brassicas become sweeter after a frost?” you can find many articles that state that sugar levels in brassica will rise when exposed to frigid temperatures. Some articles state that as the temperature decreases the starch concentrate of the plant will transform into sugar. This results in greater sugar levels and lower starch level within the plant. But where is the evidence? Where is the data showing that this is truly the case. Most of the articles that claim this are just blog posts about gardening. They offer no scientific proof that their claim is true. They are merely going off an old wives tail that they have heard time and time again.
The National Deer Association took this same claim and decided to find whether it was fact or fiction. They took several brassica species such as Kale, Radish, and turnips and tested their sugar levels and starch levels before and after a few frosts. The results did not exactly match up with the old myth. They found that there was no significant increase in sugar levels and starch levels did not decrease. So, unlike the several other articles you can find about this. They used evidence to determine the truth.
Now this raises a lot of other questions. So why is it that deer tend to eat brassicas later in the year? First, I’d like to point out my own observations on our own farm. Although many might claim that deer will not touch turnips and other brassicas before a few frosts, I have found this also to be false. Although their browse pressure may not be significant on the root of the plant, I have found that they will eat the green leaves of the plant well before any frosts. If you didn’t plant enough of them or compliment them with any other source of early season greens on the other half of the plot, the deer will most likely devour them before the season even begins. In other areas some food plotters have witnessed the deer avoiding brassicas all season long, leaving their plot to rot through the winter and into the spring. Why is this? First I would ask you if a soil sample was conducted. If not, the crop may not have efficient nutrients making it not palatable to deer. This goes to show the importance of getting a soil sample done. Just because you grew a good looking crop does not mean it will be successful. Then I’d ask how long you have planted brassicas in the area? Many times deer won’t recognize this as food if it has just been introduced to them. It could take a few years for them to notice this and start using the plot.
I have noticed on our own farm that the greatest browse pressure on brassicas does not necessarily correlate with frost dates, it is associated closer to snowfall amounts. The majority of the time I have found that deer hit our brassica plots the hardest after we have received snow. Now, is this just an illusion because their tracks and digging marks are more visible in the plot after a snowfall. Maybe. But I still believe snowfall has more to do with with their increased attraction than frosts do. But why is this? Unfortunately there is no answer to this question. Some claim that as frosts and snowfall occur other forages throughout the woods tend to die and no longer produce browse for deer. This results in more deer migrating to the lush green forage that brassica tops provide and the high protein levels the root bulbs produce. Whether this is true or not no one really knows. However we do know that brassicas can be extremely desirable to deer. This desire for whatever reason comes later in the season, therefore making it a key food plot plant to have on your property to attract and hold a deer heard throughout the entire season.