Lauterbach: Prune grapes now for bigger, sweeter fruit

Special to The Idaho StatesmanFebruary 14, 2014 

  • “GARDENING IN THE TREASURE VALLEY”by Margaret Lauterbach

    Margaret will autograph copies her book from noon to 2 p.m. Saturday, Feb. 15, at Edward’s Greenhouse, 4106 Sand Creek St., in Boise. The book costs $20 including tax and can be purchased at the event or at for pickup at the Statesman. Shipping is available for an additional $5 per book.

    Statesman reporter Anna Webb will autograph copies of the 150 Boise Icons book from 1 to 2 p.m. at the same location.

This is the month you should prune your grapevines. If you wait until later in spring, the vines will "bleed" a lot of sap, making a mess. It probably won't hurt the vine (trees that bleed aren't harmed), but it's unpleasant.

We prune grapevines so that fruits will be well sugared. If you don't prune, grapes will be small and not as sweet as they could be if the number of grapes to be served by the vine is too high.

First of all, prune out suckers arising from the roots and all watersprouts, those twigs rising vertically from a cane. Also, remove dead wood, but be careful because most of the older wood on a grapevine looks dead at this time of year. Cut each cane back to 10 to 15 buds or nodes from the trunk, wrap the cane around a support wire and tie it to the wire.

It's much better for a cane to be guided up onto a support wire rather than down, for one that arches down will develop annually unproductive and strength-draining watersprouts on top of the downward arching cane.

Especially vigorous canes are known as "bull canes," and they're not productive, either, so should be removed. Don't be afraid to prune a grapevine. You'll damage the vine more by underpruning than by overpruning.

Before doing any pruning, I'd recommend you look at the weather forecast for at least a week ahead. If night temperatures are to be below 20 degrees F. (my arbitrary number), I wouldn't prune grapevines or fruit trees.

Pruned canes could be stacked, largest arching canes on bottom, diminishing arches toward the top, in a cone fashion to create a trellis or tuteur that could support flowering vines. Edwards Greenhouse has some of these cones on display. You probably should put a solidly anchored stake in the center of this stack to thwart strong spring winds, though.

It would provide attractive support for vines such as morning glory, for instance.


Boise Parks and Recreational professionals are set to teach free courses this spring, starting Wednesday, Feb. 26. Even though these courses are free, you do need to register for them at, departments, parks & recreation, community forestry, or call (208) 608-7700, or email .

All courses will be taught 6 to 8:30 p.m. Wednesdays, in the Hayes Auditorium at the Boise Public Library, 715 S. Capitol Blvd.

The first in the series will be timely instruction on pruning fruit trees, taught by Matt Perkins, Boise city arborist and manager of the Laura Moore Cunningham City Arboretum. Pruning fruit trees is different from pruning ornamental broadleafed trees, because with fruit trees, you're pruning for fruit production as well as opening the tree to sunshine and air circulation.

On March 5, Gary Moen, professor emeritus of horticulture at BSU and an arborist, will teach tree biology. Understanding the biology will give you a good foundation for subsequent classes, although it's not a prerequisite.

Boise city arborist Dennis Matlock will teach pruning of non-fruiting trees March 12, and Ryan Rodgers, another Boise city arborist, will talk on tree selection and planting. Boise city arborist Debbie Cook on March 26 will address control of diseases and insects attacking trees in our area.

The next lecture will be on lawns and landscape, April 2. Dave Beck, of Boise Parks and Recreation, a fellow responsible for more than 300 acres of turfgrass in city parks, will speak about lawns, and Toby Norton, Boise city landscape architect, will talk on plant placement, water zones, and orientation of plants in a landscape.

Finally, instructors from Boise Parks and Recreation will focus on roses and irrigation. Andrea Wurtz will speak on care and culture of roses , and Dan Falconer will talk about sprinkler maintenance and design, and how to use a system efficiently.

Send garden questions to or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.

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