Stevia approval as a food ingredient in the EU

Certain stevia glycosides had already been approved as food additives in the U.S. European approval adds another large market for sugar-free foods and beverages. Hopefully increased use of stevia will free up more of the sugar cane crop for use as biofuels. Stevia can be grown on land unsuitable for sugar cane or field corn. It can also yield more sweetening power per acre than sugar cane can deliver.
Stevia approval will accelerate existing trend towards low calorie drinks, Wild: A regulation allowing the sale and use of steviol glycosides was published in the Official Journal of the EU on November 12, and will enter into force 20 calendar days from that date, meaning that stevia-based products could appear on sale as early as December 2.

Overwintering Stevia Plants

It’s getting cold here in the Midwest—time to bring in the stevia plants before our first hard freeze. As far north as USDA plant hardiness zone 8, stevia plants can usually survive winter in the field. The tops might die back, but the roots can survive as long as the ground does not freeze. Mulch can help prevent frozen ground.

I harvested my stevia plants more than a month ago, in September, leaving stubs of 4 to 5 inches in length. The plants have sprouted back somewhat, and we’ve had some frosts at night. That’s OK, because stevia tops can withstand a few degrees below freezing in the fall. Even if the tops are damaged, the roots can survive. But the soil will eventually freeze here. Therefore I dug a few plants for overwintering on this late October day. I square plastic used pots that are 4 inches in diameter and several inches deep. The pots should have drainage holes. If a plant is too big, the crown may be divided into two plants. A standard potting mix for houseplants will work just fine, usually including peat and vermiculite or perlite. You can even mix in a small percentage of garden soil.

The plants might survive in a sunny window. They will not grow much because of the short winter day lengths, but the roots will probably survive anyway, and sprout back when days grow longer in the spring. I prefer to keep my plants under a fluorescent shop light left on about 15 hours per day. A timer is helpful. Stevia plants thrive with the longer light period. Short days trigger more blossoming and less leaf growth. Blossoming is more stressful for the plants already weakened from being transplanted. Keep the soil moist as you would for any houseplant. Added fertilizer will probably not be needed. Slow growth is best. Stems may be harvested when they get long and lanky.  

It’s also possible to overwinter stevia roots by packing them in moist soil or peat moss and placing them in a basement or root cellar where it stays cool, but not below freezing. The survival rate may not be as high, but it is less work. The roots will remain more or less dormant until you dig them up in the spring.

Do you have a stevia question? Email Jeff at prairieoakpub@gmail.com and I might answer it in a future edition of this newsletter.

The Stevia Grower Newsletter is written by Jeffrey Goettemoeller for Prairie Oak Publishing. Jeffrey is an author, publisher, and horticulturalist. He sells stevia books and seeds at www.growingstevia.com.  

When do I harvest Stevia?

Stevia blossoms

When should stevia rebaudiana be harvested for maximum leaf yield? In most cases, the answer is to pick when blossoming begins, or when the first blossom buds appear. This is when the plant diverts resources from leaf growth to blossoming. For most stevia strains, blossoming begins when day lengths shorten to about 13 hours. Here in northern Missouri, this happens in September. So my harvest is done already. In October, I will dig up some plants for overwintering before the first hard freeze.

Day length is controlled by your latitude. In order to find your latitude, try a tool like www.earthtools.org or www.esrl.noaa.gov/gmd/grad/solcalc/. With your latitude, you can determine day length at various times during the year using a tool like the one at www.orchidculture.com or the graph in my book, “Growing Stevia for Market.”

 There will be exceptions to the rule about harvesting when blossoming begins. In far north latitudes, for instance, a hard frost may threaten before blossoming begins. In that case you’ll need to go ahead and harvest. At the equator, day length is 12 hours all the time! So at or near the equator, stevia will tend to blossom quickly. In this case, you may want to wait until plants have been blossoming a while in hopes of allowing more growth before harvesting. Harvests will be smaller but more frequent than at higher latitudes.

 Do you have a stevia question? Email me at prairieoakpub@gmail.com and I might answer it in a future edition of this newsletter.

 The Stevia Grower is written by Jeffrey Goettemoeller for Prairie Oak Publishing.