Harvesting, Processing and Storing Nettle
Answered by: Richard Alan Miller
Question from: Milos Milutinovic
Posted on: February 27, 2007

I’m from Serbia (ex Yugoslavia) and I’m interested in growing and selling herbs, especially nettle (Urtica dioica). I want to know more about nettle, how should it be harvested, processed and stored.

Most important question is who will buy (and what herbs) from my country, and how much could I export. I can get many different herbs, but I don’t have much money and resources to process them. Does anyone buys raw herbs (just dried)?

I included nettle in my book NATIVE PLANTS OF COMMERCIAL IMPORTANCE. While I wrote this back in1988, only the prices have really changed since that period, while volumes and uses have pretty much remained the same. I think the primary user in North America is now Revlon Cosmetics.

They only purchase nettle as an oil extract (European sources), but they use it in a variety of formulas. This means most regional wholesalers will also purchase smaller quantities for cottage industries and home use. It is used extensively in Europe for this purpose, so there will be a continuing growth for its domestic production.

Nettle should be harvested before the plant goes into the flowering stage. When young, the stems are still green saplings and can be cut as an herb. If the plant stems begin to for a "bark," they are worthless. The green saplings can be cut twice during a season (similar to catnip).

An average forager can harvest well in excess of 1,000 pounds wet material in one day, presuming the location of good stands. It has about a 50% weight loss, so it is considered an excellent crop for foraging. When stands can be found with more than 4 acres of flat terrain, it can be machine-harvested for really excellent profits.

For situations where nettle wants to be sun-cured, the crop needs to be turned often to prevent browning the leaf. Some companies will even accept the herb in baled form, if dried properly. A large sickle or scythe can be used, especially automated versions (like brush hogs). First cuttings can begin as early as May, and then again in August.

Europe imports only leaf, rather than herb. If the company you wish to service requires leaf only, the sun-cured herb can be processed with an edible bean-harvester type of combine, similar to those used for peppermint leaf production.

Bean harvesters are used because they have a conveyor to the hopper, rather than an auger (which tends to fragment the leaf into powder. I especially like the older models of New Holland combines. These have control of widening the knives and lowering air speed. Both are important for producing a larger leaf-part.

If leaf is sought from the harvest, then it is best to let the stem form a bark. This allows for easier drying and separation of the leaf with a combine-type action. If herb is sought, then a medium condition is required on the stem to have it dry uniformly, herbaceous-stem and leaf.

Burlap or polypropylene bags are used for leaf material, and good storage requires a heated warehouse, free of insects and rodents. Remember, when harvesting leaf, you can get only one harvest from the source. Two cutting are available, however, when putting it up as a hay-type crop.

Since nettle grows from a rhizome, cutting it only stimulates further growth. As a point to remember with most rhizomes, if it is left to go to flower, there is usually a 60% loss of rootstock while seed is produced. This is one reason why it wants to be cut before flower formation. The stem is also more marketable at this stage.

Regions like New York and Michigan could probably cultivate this as a cash crop. Yields are estimated now at more than 3 ton per acre (dry weight) on two cuttings.

As a final word, I would suggest getting your nettle certified organic (3 year process). This will absolutely guarantee a market niche with Aubrey and other cosmetic companies who would like to market in Whole Foods (and other COG markets).

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