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Tales from a Plant Addict

Fun (& a few serious) facts, tips and tricks for every gardener, new and old.

Eastern Redbud Cercis canadensis

A sure sign that spring has arrived—and is not just teasing us with a brief stint of nice weather is when the redbuds are in bloom. If you don't know what a redbud is, you have probably noticed them in past years. Redbud trees are covered in the spring with small purple-pink flowers that resemble pea flowers up close.

I was a bit surprised to find that the redbud, Cercis canadensis, has an association with Easter. In some parts of the country, its common name is Judas tree, referring to the legend that Judas hung himself from a redbud tree after turning Jesus over to the Roman authorities. From that time on, legend says the redbud was unable to grow heavy branches that could support much weight.

Whatever the origin, the redbud is not the sturdiest of trees, but many would argue it is a contender for most beautiful flowering tree of spring. The flowers are edible, and many people love their nutty flavor in salads, pancakes, or even as pickled relish!

Redbud is a legume, making it related to beans and peas. This seems odd until you see the fruits developing after the flowers fade. They look like little bean or pea pods, all lined up in neat little rows along the branches. These too are edible, when they are still green. Some people cook the seeds and butter them much like peas.

Gardeners will surely identify with the urge to see if you can actually germinate any of the many seeds produced to grow your own redbud "from scratch". It is possible, but requires two little horticultural secrets. These are scarification and stratification. To some it may sound like some newly developed scientific method, but mother nature has been doing both for thousands of years.

Scarification and stratification are needed to overcome dormancy in the redbud seed. Redbud is somewhat unique in that it has two types of dormancy at work in each seed: coat-imposed dormancy, and embryo dormancy.

The coat-imposed dormancy in redbud is due to the tough seed coat on each seed that makes it nearly impossible for water to penetrate, preventing germination. Scarifying, or mechanically breaching the seed coat will allow water to enter the seed and begin the germination process. For redbud, several options for scarification include, treatment with sulfuric acid or vinegar, one minute in boiling water, or nicking the seed coat with a file or scraping with sandpaper.

There is a germination inhibitor in the redbud embryo that prevents it from growing, even with perfect conditions. It takes about three months of cold treatment to break down these inhibitors before germination will occur.

This may seem strange, but it gives the seedlings a better chance at life. Redbud seeds are produced in the fall. If they germinated, the seedlings would not have much time to establish before freezing winter temperatures, and would likely die. Seeds that don't germinate until the spring have much more time to grow and develop before the winter.

In nature, redbuds are an understory tree, meaning they exist below the canopy of larger trees, and generally are not naturally found out in the open by themselves. Keep this in mind when planting a redbud. The south or west side of your property in the blazing summer sun would not be the best place for a young redbud.

Unfortunately, redbuds are a relatively short-lived tree, typically lasting "only" forty to fifty years. They are also prey to several insect pests, particularly scale and leafhoppers. Probably the most deadly problems are caused by fungal cankers and verticillium wilt which will cause extensive branch dieback, and even kill the tree.

Problems with fungal diseases intensify if redbuds are grown in full shade. In this situation the upper branches develop more in order to capture the little available light, and the lower branches tend to die back. The lower branches also tend to remain moist and cool in full shade, encouraging establishment of fungal disease.

Even with its few potential problems, few would argue the beauty of the redbud. There are several named cultivars available with different shades of purple-pink. 'Alba' is a white flowered cultivar. No matter what the color of the flower, I think we could all use a good dose of blooming redbuds after the long, cold snowy winter we've had.


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