Blueberries require patience from home gardener

SHAWANO — Blueberries are an exercise in patience because they’re “a very different critter from basically anything else we grow,” Scott Reuss, Marinette County University of Wisconsin-Extension educator, told 118 people interested in growing the fruit Jan. 30 at Qualheim’s True Value Hardware.

The presentation was one of a series of how-to sessions for home gardeners.

Although he covered the spectrum of growing and maintaining blueberries, Reuss concentrated on soil preparation and maintenance in his light-hearted introduction to the temperamental crop.

This included his tongue-in-cheek planting advice, “Roots go down, stems go up.”

“This is the one where there isn’t much leeway when it comes to taking care of your soil,” he said.

He was firm in saying, “Don’t buy your plants until your soil is ready” and that could take an entire year.

Productive soil starts with siting the blueberry patch, he said.

“Look up, look down, look around. Find full sun or your fruit production is going to suffer,” he added.

They like well-drained wet soil with high levels of organic matter and really don’t like frost pockets, the Extension educator said.

Also be aware of blueberries’ need for water, he cautioned, especially if you have to carry buckets any distance. In a drought year, he said, every mature shrub will need upwards of 100 gallons nearly daily.

Blueberries absolutely require a fairly acid soil, with a pH of 4.5 to 5, he said. The average pH in our area is 6.5, he said. One reason that iron, an essential part of blueberry growth, is taken up by the fruit better in soils with a lower pH.

In much of southeastern Shawano County and southern Oconto County, limestone is very near the surface and growing blueberries is really not an option, he cautioned.

One possible approach, according to Reuss, is work in a lot of elemental sulfur, up to four pounds for a typical 10 foot by 10 foot plot, at least 12 inches below the surface and wait a year. An alternative is serviceberries, also known as juneberries, although they have seeds more like grapes, Reuss said.

Take in a soil sample for an analysis from precisely where you plan to plant the blueberries down to the square yard, he advocated. “Just make sure it’s an accredited lab,” he added.

Reuss said gardeners need to remember most of Shawano County falls in Zone 4, a measure of plant hardiness. Reuss said gardeners want blueberries rated Zones 4 “or at least Zone 5 if you’re willing to try it.” As an illustration of the hardiness zone scale, Reuss said, “Your living room is probably Zone 7, depending on how cold you let it get overnight.”

“Not only do they need really low pH’s, they don’t have the same kind of root structure as any other plant that you grow in your garden. They don’t have root hairs,” Reuss said.

Unlike other plants, blueberries have to rely on what Reuss called their “true roots” for nutrient uptake. That’s why gardeners need to add abundant amounts of organic matter, he added. Leaves in the fall, including conifer needles, are the cheapest alternative, he said. Although sphagnum moss is an alternative, Reuss said it’s not a sustainable resource and one to avoid.

“Mulch matters. It is a big deal,” Reuss said, adding mulch aids in weed control and more efficient water retention.

Grass clippings can be part of the mulch but need to be mixed with other, coarser, more stable materials like wood chips and bark chips. Do not use butternut or black walnut leaves, he said. Conifer needles actually benefit blueberries but also can invite meadow voles and other pests.

Mulch provides temperature modification.

“By having the mulch on there, we keep the soil and the roots at a much more stable temperature,” Reuss said.

This is important because of blueberries’ intolerance of drought conditions, he added.

“Their roots will literally cook,” he said.

From planting, there are another few years before you can start reliably harvesting fruit, Reuss said. In that respect, blueberries are no different than raising a fruit tree “because it’s also a woody plant,” he added.

Home gardeners should consider the “half-high” blueberries, hybrids between the “high” and mostly-wild “low” varieties, Reuss said. Most of the available varieties came from plant breeders at the University of Minnesota, assuring their hardiness.

Reuss listed these varieties as being adapted to this area: Northblue, Northcountry, St. Cloud, Patriot, Bluecrop, Pink Popcorn and Bluecrop.