How Not to Lose Fruits to Frost
Now: I've been vegetable gardening for seven years and have had a place of my own for three years now. On that one acre, I have raspberries, blueberries, red and black currants, red and black elderberry, chokecherry, gooseberry, serviceberry, apples, pears, paw-paw, etc….
I'm wondering if you can steer me towards fruiting trees and shrubs that are less susceptible to being blasted when a warm winter is followed by a 'normal' cold snap at the beginning of Spring. That's what happened to a lot of us last winter (2016), and I can only imagine it will happen more often. As I plant more of my acreage, I would like to concentrate on crops that set their fruit later.
---Charles in Vernon, Connecticut
A. We should note that the subject line on Charles' email was "battling climate change"; and his concerns are valid. A warm winter can—and just did—set early-blooming plants up for a knock-out punch in early Spring. But it's not the same thing as a {quote} "late frost".
Now, this is a good opportunity for me to repeat my warning that you can't garden by the calendar alone. The "last average frost date" assigned to your growing region is just that—an average. Some years you'll be frost-free long before that date, and some years it'll drop into the 20s two weeks after it. That's why I always urge cowardice in putting tropical plants like peppers and tomatoes outside. The smart money says to wait until nights are reliably in the 50s.
And if you ignore that advice with tomatoes and a late frost blows through, you can easily replace those plants. But if a late frost blasts the flowers on say, your peach trees….
Which is exactly what happened last year except that it wasn't a 'late frost. The plants were blooming way ahead of schedule because what turned out to be the warmest winter in history had lured them into opening their flowers much too early. And there's no replacing those flowers at the garden center. That's why "crop failure" is one of the scariest phrases in farming. You invest a lot of time and energy into your trees and then you get zero return that year.
Now, we asked our resident fruit growing expert Dr. Lee Reich for his advice on this; and on the very same day we told Charles we were going to answer his question in depth. Their responses arrived together, and confirmed some basic truths. Lee wrote: "We're mostly talking about fruits that bloom the latest in the Spring: persimmon, raspberry, blackberry, and elderberry come to mind. Also, some fruits like cornelian cherry and paw-paw have frost resistant blooms. And finally, I've never lost a crop of blueberries, even on my frost-prone site, and even last year."
Charles said something remarkably similar. He wrote that he had harvested a lot of raspberries and a good number of blueberries and black currants—all small fruits, and all later blooming than fruit trees like apples and pears.
Now, there are "late blooming varieties" of those fruit trees. And they're good choices for growers in the North. They're not late-blooming enough to be any kind of a guarantee, but you'd be foolish not to choose those varieties in a chilly region.
Gardeners! Don't pick varieties just because you like them in the supermarket; grow the ones that are best for your region—and resistant to your local pests and diseases!
We also note that Charles reveals he's only been on this property for three years. So if he planted those fruit trees, they (and his other, smaller fruits) are still getting established. But last year's losses were not his imagination; I tried to keep one of my blooming peach trees going on that legendary cold night by moving our gas grill underneath it and running it on low with the lid closed.
Which sounds clever…
…but it ran out of gas in the middle of the night.
However, I did save a different tree that was much closer to the house by hanging an old string of incandescent Christmas lights in the branches, which worked perfectly. We got a nice crop of peaches from that tree. You might have to haunt yard sales to find old non-LED warm-to-the-touch Christmas lights (or go rummaging through the neighbors' attics), but it's worth it. Lee also suggested draping row cover material like Reemay over the trees in these kinds of situations, which would help prevent frost from forming on the flowers.
And that brings me to some final bits of advice.
• 1) Make sure new trees are dwarf or semi-dwarf in size, so that you can do things like cover or light them.
• 2) If you really like the 'light-em up' idea, plant new trees close enough to the house that you can safely run extension cords out to them.
• And 3) Be sure to plant any new fruit trees in your areas of highest elevation, not down low in the pockets where frost forms first.
