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Kim Eierman

Kim Eierman

Founder of EcoBeneficial!

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Winterberry (Ilex verticillata)

Should I buy Winterberry cultivars or straight species plants? Will deer browse Winterberry?

Question:

I understand that berries of some winterberry cultivars may be too big for birds and may have less nutrition. Should I buy winterberry cultivars? I am in Maryland and have not seen the straight species anywhere. Will deer browse winterberry?

Answer:

I prefer to use straight species plants whenever possible, thinking that Mother Nature really does know best and provides the best resources. We lose some genetic diversity when we rely upon cultivars and favor our own aesthetic tastes. Sometimes our selections (i.e. cultivars with oversized or odd-colored fruits) may not be the best resources for creatures we are trying to attract and support.

Food of Desperation

Not all birds eat fruit, but those that do are opportunistic feeders and will eat what is available when they are really hungry, and/or if it tastes good.  Winterberries are really a winter desperation food when not much else is around – not terribly nutritious (low in fat and protein; high in carbs) and not very tasty. Their taste improves as winter progresses and birds get hungry enough to eat them.

I suspect that the nutrition profile of different cultivars can vary, just as different selections of produce, which humans eat, can vary nutritionally.  I have not seen an analysis of this, and hope that some wonderful university or non-profit will undertake a study.  (The University of Rhode Island has some great information on nutritional values of berries for migrating birds).  For wildlife, I avoid cultivars with odd-colored fruit, like ‘Winter Gold’ or ‘Golden Verbloom’ or cultivars like ‘Little Goblin,’ a tetraploid with oversized fruits.

Finding Straight Species

As you have experienced, it can be tricky to find anything but cultivars.  Fortunately, there are some good native nurseries in the U.S. that often carry straight species plants.  You mention that you are from Maryland. The Maryland Native Plant Society has a terrific list of local native nurseries on their website, as do other native plant societies and Wild Ones chapters in the U.S.

Seasonal native plant sales run by non-profits and volunteer organizations can be another good source for straight species plants. Most of these sales occur in spring or fall.

If you cannot find straight species winterberries, I suggest that you favor cultivars that have similar characteristics to straight species plants, in terms of plant and fruit size, fruit color, leaf color, etc., for best ecological performance.

“Mates” for Winterberries

Remember that Ilex verticillata (Winterberry) is a dioecious species – there are male and female plants. The flowers are cross-pollinated by bees (and possibly by some fly species). You need both male and female plants, and they need to be in bloom at the same time, to produce fruit on the females. Selecting paired male and female cultivars is something of a hack that makes this easier. You don’t need to plant an equivalent number of females and males. I like to use “harem” of four females to one male, planted in fairly close proximity to enable bees to cross-pollinate easily.

Deer and Winterberry

Winterberry is not a bomb-proof plant when it comes to deer.  Rutgers rates it a “B” for “rarely severely damaged” and Ohio Landscape Association categorizes winterberry as a plant “deer eat less often.” As you have probably seen in your own landscape, deer browse varies depending on the other food sources available and by the herd itself.

In a really bad season with few food sources, deer will eat most anything.  Unfortunately, most alien invasive plants are not eaten by deer – one of the reasons deer help themselves to the plant buffets in our gardens.

If you do plant winterberries, protect them until they get large enough to withstand some browse.  It helps to plant a large mass of the plants for more resilience, remembering to plant both male and female plants that are compatible.  Also, plant some species that deer really dislike around the plants they favor.

Sadly, we are losing a great deal of biodiversity to deer browse.  It’s a conundrum – if we only plant species deer dislike, our ecosystems suffer.  With deer populations totally out of balance in much of the U.S, this is an issue that requires attention at the municipal level through deer management programs and forest restoration.

Happy planting and thanks for following EcoBeneficial!

From Kim Eierman

 

Photo: Ilex verticillata
Photo credit: Flickr/Chesapeake Conservation Landscaping Council

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