Wednesday, September 28, 2011

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 or With your latitude, you can determine day length at various times during the year using a tool like the one at 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 and I might answer it in a future edition of this newsletter.

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