Grape holly a shrub with winter appeal

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By Ted Manzer

Friday, January 11, 2019

Recently, someone asked me about shrubs that were showy in winter. Obviously, camellias fit that bill as do winterberry holly and a few others. Mahonia, often known as grape holly, is an underused adaptable shrub that also has winter attributes.

I have one that is in full bloom right now. It has bright yellow flowers which will give way to purple grape-like fruits later. Broad, multibladed leaves are spiny and shiny. Cut off a twig and you will find the wood is yellow. That shouldn’t be a surprise as this is not a holly at all. It’s a member of the barberry family.

Barberries have yellow wood, not that it’s used for anything commercially. Several years ago, my daughter conducted a science project using natural plant dyes that could be collected in winter. Mahonia wood makes a beautiful colorfast yellow dye for fabric.

There are many species of Mahonia. The most common is Oregon grape holly, but numerous others are commercially available. One gaining popularity is called “Soft Caress.” It is a spineless cultivar that has a palm-like appearance. It also doesn’t get too tall, making it useful in more situations.

“Wintersun” and “Charity” are taller cultivars that make great specimen plants. They usually attain heights of 10-15 feet. Yellow flowers adorn these plants from late fall to late winter.

These evergreen barberry cousins thrive in moist but well-drained soil. Soil pH is not very critical. Grape hollies also are best in partial sun but will tolerate substantial shade. One thing to consider is that they will bloom less in shadier locations.

Most literature list hardiness as zone seven or possibly six in sheltered locations. Some sources claim it to be hardy to 30 below (zone 4), but I think that’s pushing it.

I have one planted next to a loquat. The loquat was nearly totally killed by last winter’s extreme cold during the first week of January. The grape holly wasn’t hurt a bit.

Sometimes they are difficult to establish. However, once ensconced into their new home they require very little care. They aren’t heavy fertilizer users and they don’t require much pruning. However, plants can be encouraged to grow prostrate if taller canes are removed. In some situations, this can be effective.

Few diseases or insects attack Mahonias either. Deer usually leave them alone, but in winter if food sources are short, deer will nibble at them, especially the flowers.

Colorful fruits are edible but quite sour. With a generous influx of sugar, they do make a flavorful jelly or jam. Usually no pectin needs to be added as fruits are rich in it already.

Medicinally, grape holly is a major player. Stem and root tissues are used to treat stomach ulcers, acid reflux and other digestive system maladies. Herbalists prescribe topical formulations to combat psoriasis.

Grape holly also contains a chemical called berberine. This is often used to treat high blood sugar. Holistic practitioners also use berberine to combat high blood pressure. Those with low blood pressure or people with organ transplants should avoid it.

Ted Manzer teaches agriculture at Northeastern High School.