About Barberry Species as Shrubs, Invaders, Fungal Host, and Bonsai Trees

            Barberry aesthetically makes a delightful bonsai due to its small, colorful leaves, flowers, and berries. They are frequently used in landscaping which means that they are readily available to those who keep their ears to the ground for unwanted plants to salvage like myself. Today I want to share some information on these plants, good examples of successful barberry as bonsai, and some brief comments on techniques for this species.

I am also listing some of my barberry prebonsai/yamadori for sale. Help me downsize my collection so I can focus on my PhD thesis! Pictures, prices, and delivery options in Columbus, OH, or surrounding states are listed here. I am open to hearing offers!

Sections:

1. Barberry Growth Habit
2. Barberry's Invasive Potential
3. A Disease of Concern for Barberry Bonsai - (Wheat) Black Stem Rust
4. American Barberry - Berberis canadensis - as Bonsai
5. Barberry Bonsai Technique Commentary & More Examples

Here is one stunning example of Japanese barberry bonsai by Ed van der Reek in Europe. They do get a great fall color! Source - Ed-Bonsai.blogspot.com

I. Barberry Growth Habit

              Barberry (Berberis spp.) is an adaptable genus often found in landscaping. They naturally make clumps and the clump form often has fused bases underground. Thus, they take a very long time to develop thick single trunks if you ever happen to find such a tree! Roots also like to sprout additional shoots to propagate themselves; they also spread through berries which can be problematic.

II. Barberry's Invasive Potential

            In some US states, their berries lead the non-native Japanese Barberry or European Barberries (Berberis thunbergii and vulgaris, respectively) to escape cultivation and invade forests, but luckily this is only officially an issue in Ohio with the European Barberry. However, when you stumble on any barberry in the woods in Ohio, you can assume it is non-native and cut it down as we have no native species here in Ohio. I do occasionally find them in our woods but not as often as other local invasives like honeysuckle. Learn more about identifying the non-native Japanese and European barberry species here.

Source. See there for other identifying traits also!

III. A Disease of Concern for Barberry Bonsai - (Wheat) Black Stem Rust

            Within the last 100 years, barberries have proven to give rise to massive economic losses for wheat farmers due to their participation in a fungal life cycle that transmits between barberry and wheat. The USDA has compiled an interesting article with lots of historical information on this disease, its past impacts, efforts and successes in combatting it, and ongoing efforts. While formerly Black Stem Rust epidemics could wipe out as much as 50% of wheat yield in a given year in the US, it appears to be nearly a non-issue now that the susceptible European barberry species has been nearly or entirely eradicated from the major wheat-producing states (but this species still persists in the NE US) (cite-USDA, cite-OSU), but like all good public health programs, this is only due to ongoing and continuous efforts to prevent the invasive barberry from re-colonizing those important midwestern agricultural states.

One instance of a bad year for (Wheat) Black Stem Rust! You can see the geographic distribution in the US here. Source

Here you can see the downward trend of the wheat stem rust epidemics following successful programs for local eradication and quarantine of susceptible European barberry. Source

            Luckily, the Japanese barberry/B. thunbergii that we are using for bonsai here is NOT susceptible to wheat stem rust (cite-USDA2, cite-OSU)! Just in case, if you see any symptom like the leaf below, it's best to remove infected foliage, treat it with appropriate fungicide, and possibly discard the plant! I have not seen any evidence of this on my Japanese barberries though in the last 4 years I've been growing them.

This is what Wheat Rust looks like on a European Barberry leaf (note the serrated leaf edge, whereas Japanese barberry has a smooth leaf edge). Source

IV. American Barberry - Berberis canadensis - as Bonsai

            There is also at least one species of native barberry which is found wild in the southeastern and parts of the Midwest US. See the range map here. HOWEVER, this is a species that is susceptible to Wheat Stem Rust, so if you collect or cultivate this species you must pay close attention to the local rules surrounding the sale and quarantine of it! Also be sure to learn more about the black stem rust life cycle, signs, symptoms, and treatments so if your plant does contract it you can take appropriate actions right away to limit the spread.

            With that disclaimer though, it looks like American Barberry does make an excellent bonsai! If you are in an area with native B. canadensis, be sure to look into local resources to confirm identification. It will be easily confused with the European barberry we discussed above as both have serrated leaf edges (Source). The European barberry has fine serrations (20-30 per leaf) whereas the native US barberries have coarser serrations (<10 per leaf) (Source). One good local resource from North Carolina has pictures of 2 native species of barberries here.

An American native barberry bonsai from the North Carolina Arboretum Bonsai Collection. Source

Note the coarse serrations of B. canadensis compared to the fine serrations in the earlier photo of European barberry. Source

V. Barberry Bonsai Technique Commentary & More Examples

            Bonsai-wise, these make for great miniature forest or clump-style bonsai due to their growth habit, naturally small leaves, and vibrant colors at any time of year ranging from pink/purple during the growing season to yellows and reds in fall. The main downside that barberries have for bonsai is their fine and sharp thorns which will prick you at some point if you own one! For this reason, I employ clip-and-grow techniques to produce changes of direction in my branches and to get the dense foliage pads rather than wiring, but it responds and transforms into a bonsai using this technique in a few short years! If you dare to brave their barbs you may even wire the branches. I have pruned throughout the growing season, repotted these plants during early-mid spring, and dug spring-fall with no unexpected issues in all these cases. The riskiest operation for barberry bonsai's survival is the initial dig, but I have seen that cutting them back at the time of digging reduces shock as it lowers water demands on the roots, especially for those "now or never" summer digs.

Next time... I will provide a more detailed write-up on pruning barberry bonsai once they are in leaf! This is a topic I photographed for last year but haven't made time to follow up on yet.

Bonus pictures of barberry bonsai

Japanese barberry by Gregg Hammond.

Japanese barberry by John Recuelo.