Dear Aggie: Every time I plant blueberries, they die. What am I doing wrong?
I find that most gardening rules are less than useful. Usually, there is more than one way to get things done in a garden. That said, one rule that gardeners should absolutely follow is “Right Plant, Right Place.” Every plant has unique growing requirements. These include preferred sun exposure, drainage, amount of water received, average temperature, nutrient levels, and soil pH. We would never plant lemon trees outdoors here in Northern New York. Similarly, sugar maple trees would quickly wilt in the Amazon. Unfortunately, we gardeners are a stubborn bunch. Like Cinderella’s wicked sisters, many try to make the shoe fit regardless of how big our feet are. We repeatedly see gardeners in Jefferson County try and fail to grow blueberries.
Though native to the East Coast, blueberries require acidic (ericaceous) soils with a pH somewhere between 3.8 and 5.5. For reference, lemon juice has a pH of about 2 while black coffee has a pH of about 5. A neutral pH is 7. Except for a few locations around Adams, most soils in Jefferson County are neutral to alkaline, with a typical pH ranging from about 6.7 to 7.2. This is higher than blueberries can tolerate. Blueberry bushes planted in alkaline soils are unable to take up nutrients and quickly die. This explains why gardeners in other northern locations can easily grow blueberries while we cannot.
That doesn’t stop people from trying though. We see many local gardeners determined to grow blueberries despite their soil’s alkalinity. They resort to fertilizing with sulfur compounds (e.g. Miracid) or adding a few handfuls of peat moss. Similarly, commercial growers have gone as far as adding sulfuric acid to their irrigation water. These methods do work, but only for a short time. Unfortunately, our soils contain significant quantities of calcium, which originates from our limestone bedrock. In a matter of weeks to months, this calcium pulls the pH back into the alkaline range.
So how do some local gardeners succeed in growing blueberries? They adapt the growing environment to suit the plant. Just as lemons must be grown in a protected greenhouse, blueberries must be planted in artificial or imported soil mixes. Acidic (ericaceous) growing mixes typically contain things like composted pine bark, expanded shale, cottonseed meal, coir, peat moss, and even coffee grounds. Blueberries are best placed in raised beds or in pots to keep calcium from leaching from native soils into the mix and neutralizing the pH.
What do you do if you can’t change your soil? Then it’s time to change the plant. An alternative to blueberries is the honeyberry, otherwise known as haskap. Originating in Russia, honeyberries thrive in alkaline soils, are hardy to Zone 2, and are especially disease resistant. While older cultivars were astringent and best suited for jams or pie, newer varieties such as “Aurora” are sweeter and can be used in place of fresh blueberries. The biggest challenge to growing honeyberries is remembering to pick the berries in June before the birds get them.
If you’d like to learn more about growing either blueberries or honeyberries in Jefferson County, we will be hosting a seminar comparing cultivation of blueberries to honeyberries at 6 p.m. Sept. 16. For more information, visit our website at wdt.me/honeyberries.
Question answered by Mike Nuckols, Commercial Horticulture, email@example.com.