The Horsechestnut or Buckeye

The Horsechestnut or Buckeye
Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist
The common horsechestnut (Aesculus hippocastanum)is a big tree at maturity reaching 75 to 100 feet in height with a spread of 40 to 70 feet. You can see one of these big guys at the Benton County Courthouse in Prosser.  As you will note, this tree is best suited to parks, arboretums, and building with large expanses of lawn area.  It really isn’t one that most people should plant in their yards.
The nuts are produced in spiny capsules which are a nuisance with the large numbers produced by a mature tree. The nuts, with and without the spiny capsules around the outside, are popular ammunition for children.  While you can’t eat these nuts, they are fun to collect.  You can even start you own horsechestnut tree quite easily.  Just take some moist potting soil and place in a plastic container with a cover.  Bury several nuts in the potting soil.  Close the container and put it in the vegetable bin of your refrigerator for three months or more.  Late next winter or early in the spring take them out and plant them outside where the soil will be kept moist.  Treated this way, the nuts will germinate and grow.  If you give this a try, only use fresh nuts and “plant” them in your refrigerator soon after harvest.  If the nuts dry out, you’re out of luck.  This is an activity kids will love to help you with.  Just make sure you have room to grow this big tree.
Here’s a special note about chestnut “nuts.” Native Americans did use horsechestnuts as a food source, but only after they leached out their poisonous compounds in boiling water.  However, horsechestnuts should definitely be considered poisonous.   
The edible chestnut looks quite different from the inedible horsechestnut.  The edible chestnut has a dense, dangerously spiny capsule and the horsechestnut has a capsule with shorter, less dense spines.  The edible chestnut is somewhat rounded with a slightly pointed end.  The horsechestnut is smooth with no point and sometimes flattened a bit on one side.  Looking at the tree’s leaves also helps.  Horsechestnut leaves are compound and consist of five or more “fingers” or leaflets. Edible chestnut leaves are single, entire leaves.