Thicket Bean-The Perennial Wild Bean
Related to the lima bean, thicket bean seeds are hard to find. This is partly to blame for the exploding nature of the seed pods during harvest as well as lack of interest in the gardening community. I grew a population of thicket beans in southwestern Michigan over the course of a decade. Each year I learned a little bit more about this unique bean including its growing habits, harvesting and taste testing. In 2017 I harvested 2 ounces of dry seeds from my plantings. In 2018 I harvested 1 lb. 10 ounces. In 2020 I hit a record of 4 lbs.. It turns out that once established the thicket bean produces copious amounts of beans. I also discovered that thicket bean will fruit in one year from seed. So it is quite a precocious bean.
This strain I feel is an earlier form and has fully ripened in southwestern Michigan making it one of the most northern forms under cultivation. Certainly others could grow but wild beans need a longer season to fully ripen. For me that means the pods turn brown starting at the end of September here and go for up to a month prior to harvest. It is a late bean but we also have it located in an area that doesn't allow all day sun. This would likely help.
On its hybridization: it is possible but why would you do that.? My thought is if you create another crop, then what are the benefits of the new hybrid over the older 'unimproved crop'? With thicket beans the small size is preferable in cooking and if the yields are high then what is to improve? Harvesting would be one if it was grown like other row crops. I like the idea of a lima bean cross with it and it is possible very easily. If you do too, then plant your limas very sparsely in the thicket bean trellis. For me, I planted in mid to late June and sometimes into July. Then the pollination will overlap. With bees, hover flies, honeybees and carpenter bees and butterflies you might find some hybrids in the next generation. After many hours watching pollination, I do remember thinking nothing seems to be going to the lima beans during the day and I certainly did not see anyone going from thicket bean to lima bean or vice versa. Hmm something is going on in the bean patch!
Here is how to germinate the seeds: Wild beans have a hard seed coat. If you plant them as they are, roughly 1/2 to 2/3 will germinate the first year. To increase the germination rate, soften the seed coat by using a fine grit sandpaper and gently rub it on the seed. This will scar the seed and remove some of the shine. This will then make them imbibe water easily and then sprout. You can then plant directly outside under 1/2 inch of soil. The seeds throw a taproot first and then the top will come up slowly over the course of a month. Or you can soak your seed or put in a damp paper towel until sprouting begins and then plant. Roots can go to 18 inches deep in one year and form a carrot type root. Pretty much grow like any other bean
Diseases of thicket bean include leaf rust which will defoliate and weaken the plant. Keep in check with biological insecticide Serenade which prevents its spread. This has worked well for me.
9000 Seeds Per Pound
|Genus & Species||Phaseolus polystachios|
|Seed Source||Michigan-Originally from the east coast this seed source was given to us by Eric Toensmeier. It is quite different than the Prairie Moon Nursery seed source which is black. Ours is a mix of black and brown which is mottled. Likely there are others within the U.S, as well as it was probably cultivated at one point prior to annual beans.|
|Height (ft)||15-30 ft.|
|Width (ft)||4-6 ft.|
|Pollination Requirements||Carpenter bees, hummingbirds, other solitary bees, cabbage butterfly, honeybees|
|Soil||Found as a river plain species but appears to grow in rock and sand with ease.|
|Climate||Zone 5-10. Adaptable and maybe even desert proof once established. Not good in high moisture locations in the summer as this can create rust which defoliates the plant early.|
|Ease of Cultivation||Easy to grow and fruit. Avoid shade and other wet conditions as it is susceptible to foliage diseases which cause premature leaf drop. Not a root to overwintered in containers. For me it was a 100 percent failure to grow in pots in hoophouses. By year three, yields will greatly increase. Nitrogen fixing nodules are produced at this time as well. From seed, some plants will flower and fruit the first year.|