BLUEBERRIES NEED ACIDIC SOIL

Root Concerns is a gardening newsletter produced by the Cornell Cooperative Extensions of Rensselaer, Albany, and Schenectady Counties. Because its contents have not been previously indexed by Internet search engines, relevant articles from past issues will be occasionally reprinted.

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Root Concerns  -  July, 2012  Volume 6 Number 6   Page 1

It’s the gardener’s job to meet the plant’s terms, and blueberry plants make it clear that they will not be taken for granted. Countless times, the gardener has the blueberry plants on order, in the car’s backseat, or waiting un- potted next to a hole, when he vaguely remembers he should be concerned about the soil. Ah yes, the pH needs to be low for blueberries, right? When the test shows a 6.2, trouble arises, since the plant demands a 4.5. It seems perverse that a sweet berry should come from such sour soil, but there you have it. The gardener can add sulfur to acidify, but sulfur takes months to work. 

Source: UMN Extension

Meanwhile, the blueberry plants can’t stay in the backseat, so the gardener plants them anyway. Then those healthy blueberry plants become stunted. The leaves yellow. Instead of getting larger each year, they actually diminish, akin to a modern investment portfolio. Then one spring, they silently reach the point of no return.  It may be a tart lesson, but if one is to have blueberries, one must pay attention to the soil. Don’t be lulled into thinking that all the Hudson Valley has acidic soil, and since blueberries grow just fine in Grafton, they’ll thrive in your backyard, too. Take it from an old soil tester (me), soil pH varies wildly from place to place in these parts, and while much of it is below 7.0 and technically is acidic, it just isn’t acidic enough for Vaccinium corymbosum. Have a pH test done today, add your sulfur tomorrow, and re-test in six months. Only when the pH is in the range of a lowly 5.0 should plants be ordered or purchased. Should you be a successful as a blueberry farmer, you’ll have other things to worry about, especially the birds, who are looking forward to the crop as much as you. But that can all be worked out with netting or the construction of giant chicken-wire enclosures, if you’ve got the right soil.

But here is the good news: today, at least we know what blueberry plants want. A century ago, people loved eating wild blueberries, but plants taken from the woods and put into cultivation failed to thrive. No one had the foggiest idea why until a U.S. government botanist named Frederick Coville unlocked the secret. A Cornell graduate, the perceptive, curious outdoorsman explored Death Valley, helped found the National Arboretum, and published 170 books and papers about plants during his lifetime. All very notable achievements, but to a lover of blueberry pies, muffins and ice cream, I’m awfully glad that in about 1910, he discovered that blueberries required acidic soil.

The following year, Elizabeth White, a cranberry-baron’s daughter, read his work and sent men through the New Jersey Pine Barrens searching for the choicest blueberry plants. These were propagated, cultivars selected, the soil amended, and the first commercial crop was picked in 1916. With a little knowledge, sweat and planning, we can grow our own in the backyard, too.

Text by David Chinery, Rensselaer County Extension