Sunday, December 20, 2009

The great black walnut experiment is under way

Walnuts with their husks (hulls) are at top. They're about the size of a tennis ball. The hulled walnuts are at bottom.

I obviously have a lot to learn about black walnuts. For example, take this passage from the Minnesota State Extension Service: "Take care when hulling or shelling walnuts. The practice of driving over nuts with an automobile can be a dangerous one. Nuts and broken shells may be thrown into the air by the tires, possibly causing bodily injury or property damage."

Huh? Driving over walnuts with a car?!

Apparently, this is a fairly routine procedure for hulling if a quick google search is any indication of how prevalent the practice is. Walnuts deserve a lot more respect than I realized.

Nut trees have always seemed a little mysterious to me. Trees grown for fruit or shade were a part of my childhood, but nuts -- when we had them -- always came in a bag or a can from the grocery.

So I was excited when a package containing black walnut seeds arrived in the mail in October. Chrissy sent us black walnuts harvested in Michigan's Upper Peninsula. And it was a revelation to me that black walnuts had a husk that had to be removed. The husk can be used in making dye and there are lots of warnings to use heavy rubber gloves when handling them or risk stained hands for a long time.

Lucky for us, Chrissy sent us both hulled and unhulled nuts so we didn't have to back the Honda over the nuts and risk "bodily injury."

Checking for damage to the seed. The two floating at left were discarded.

But we did need to check the hulled nuts for insect damage or other injury before planting. That meant plunging them into a bucket of water. Floaters were no good and needed to be tossed (but not in the compost; walnuts contain juglone which can kill or stunt other plants). Those that sank were viable and good for planting.

The good seeds were planted in soilless mix in one-gallon nursery pots.

That gave us 14 nuts to pot and place in the cold frame. Walnuts need stratification (cold treatment) to germinate; we're going the natural route and just leaving them outside all winter.

Even though its nuts have good flavor, black walnut (Juglans nigra) is grown more for its lumber than for its nuts; English walnut (Juglans regia) is the one that's grown for commercial nut production because it's easier to harvest and crack.
The walnuts went into their pots Nov. 4. I'll report back in the spring.

The seeds were covered with a couple of inches of soilless mix, tagged and placed in the cold frame. Information from the Extension Service suggests we can expect maybe half to germinate. (These pots since have been covered with snow.) 

Details on growing and harvesting black walnut can be found here and here and here.

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