Stevia: Growing, Harvesting, Drying, & Using this Sweetener

by Catherine Haug

Stevia with flowers

See also:

(photo of Stevia herb with flowers Wikipedia)

Although stevia is a sweetener, it is neither a sugar nor an artificial sweetener. It is the Stevia rebaudiana herb, a member of the sunflower family, and contains sweet substances known as steviosides that are 200-300 times sweeter than sucrose.

It can be grown in our valley, and will be a valuable sweetener when sugar becomes scarce (to reserve precious sugar for food preservation and other non-sweetening uses). Stevia cannot be used like sugar for food preservation.

It is also valuable for diabetics and others who must avoid sugar for health reasons. And it may improve insulin sensitivity for those who suffer from metabolic syndrome, and increase insulin production for type-2 diabetics.

Growing stevia in Montana

I have no experience growing Stevia. The information provided here is from several online sources as noted (See Reference section).

A perennial native to central and south America, stevia can be grown as far north as southern Canada, but in colder climes such as ours, it will likely not survive the winter outdoors. So after harvesting, move the scaled-back plant indoors for the winter (1); see below for more detail.

Growing

Most sources recommend starting with transplants, as it is difficult to grow from seed, and stevioside levels can vary greatly in plants grown from seed. Not all stevia plants produce the same level of sweetness, so use discernment in selecting your transplants. If you wish to try seeds, check out Starting Stevia from Seed. (4)

See Sources for mail-order sources of transplants or seeds.

Before transplanting, try to harden them off in a protected area for a couple weeks before transplanting. Soft, succulent plants will usually die after transplanting. (3)

To transplant to your garden, wait until all danger of frost is past, and soil temperature has reached at least 50 degrees, as stevia is sensitive to low temperatures. Choose a cloudy day or an evening for transplanting. (1, 4)

“Use a trowel to set the plants a little deeper than they were in the pot. In a 3-foot wide bed, use two staggered rows so that plants are not directly across from one another. Space plants 12-18 inches apart in the row.

Gently firm the soil around the plant with your hands. Avoid walking or kneeling on the bed itself so the soil stays loose. Water the plants well with a gentle soaking right after transplanting. A little mulch around new plants will prevent rapid drying on sunny days.” (5)

You want rich, loamy soil, high in organic matter; top-dress with compost if your soil is sandy. Raised beds, 4 – 6 inches high and 3 – 4 feet wide are ideal. (1, 3)

Mulching after weather is consistently warm is recommended, especially if you are not watering with soaker hoses. (3)

Stevia also grows well in containers. Choose a 10 – 12” diameter pot and fill with a lightweight growing mix. Top dress with mulch or compost. (1)

For good growth you need about 3 – 4 steady hours of sunlight per day. (2) If there is considerable summer sunshine, partial afternoon shade is preferred. Long spring & summer days favor leaf growth; short days trigger blossoming. (4)

Frequent light watering is recommended; don’t over-water but keep somewhat moist, not letting it dry out completely. (2) Too much soil moisture can cause root rot. The best watering method is the use of soaker hoses. (3)

Harvesting

Harvesting should be done as late as possible (but before a killing frost), to intensify the sweetness of the leaves. Cover your plants during an early frost to maximize growing time and sweetness. When ready to harvest, cut branch with pruning shears before removing the leaves.(1)

If you plan to overwinter your stevia indoors, leave 1/3 of the stem length on the plant. (4)

The leaves can be used fresh, but the bulk of your leaves should be dried. See below.

Propagation

To continue propagation from year to year, you have two options:

1. Move plants from garden to a pot before a hard frost, then bring indoors to over-winter. Take root cuttings in early spring for later transplant to the garden:

“Bring [harvested] plant indoors in the winter with the help of a grow light or fluorescent shop light left on for 12 – 14 hours daily (use a timer).  Pots as small as 3 inches wide may be used. Cuttings from these wintered over plants will provide fresh plants for the spring.

Stem cuttings root easily in late winter or early spring in horticultural grade vermiculite with 14-16 hours of fluorescent light per day. Use small cell packs or other containers with holes in the bottom and water from below as needed to maintain constant moisture. Cuttings should be 2-4 inches long with at least 2 leaf buds above ground. Remove all but 2 or 3 small leaves. After 2-4 weeks, transplant to larger pots with a light soil mix and allow to grow another 2-4 weeks before transplanting outdoors.” (3)

“Indoor plants can produce useable amounts of stevia and support stock plants for taking winter cuttings. The plants tend to look half dead by the end of winter, but they usually sprout back nicely in the spring.” (4)

2. Take cuttings in the autumn, root them, then grow indoors until ready for transplant in the spring. To root and grow the cuttings, follow instructions above, or:

“Cuttings need to be rooted before planting, using either commercial rooting hormones or a natural base made from willow tree tips, pulverized onto a slurry in your blender.

After dipping the cuttings in such a preparation, they should be planted in a rooting medium for two to three weeks, giving the new root system a chance to form.

They should then be potted — preferably in 4.5-inch pots — and placed in the sunniest and least drafty part of your home until the following spring.” (1)

Using the leaves

The steviosides are found in the leaves of the stevia plant. These leaves are collected and dehydrated for storage. You can use the fresh leaves, but properly dried leaves are sweeter, and will remain sweet for several years if stored properly in an air-tight container, such as a glass canning jar. (4)

Drying the leaves

Place leaves on a screen or net; air circulation is more important than heat. Choose a moderately warm fall day and quick-dry in full sun in about 12 hours (which can be difficult in late September Montana). A home dehydrator on low heat can also be used, although sun drying is the preferred method. (1)

Using dried leaves

To use dried leaves, simply crush them by hand, or grind them in a coffee or herb grinder; crushing/grinding helps to release the sweetness of the leaves.

Whether fresh or dried, one stevia leaf is enough to sweeten a cup of tea or coffee, or a glass of lemonade. You can also add them to baked beans, sauces, salad dressings, soups and stews, just as you would with other herbs. (3)

Remember, the sweetness is not consistent from leaf to leaf, so it is difficult to quantify how much to use. A good rule of thumb is to use 3-4 teaspoons of Green Stevia Powder in place of 1 cup  cane sugar. Here again, the conversion rate varies according to the recipe. (6)

Note that because it is green, dried stevia may not be attractive in most baked goods. It also has a licorice flavor which needs to be considered.

Stevia extract (tincture)

As with other herbs, an extract can be obtained as a tincture of alcohol or glycerin. This is perhaps the best type of stevia extract because it is minimally processed. It is especially useful for sweetening beverages such as lemonade, coffee and tea.

However, it is difficult to be consistent from batch to batch when you make your own, so it is hard to know how much to use in recipes such as baked goods where you cannot taste the final product until after it is cooked. Keep records of each batch to help you hone your skills toward achieving consistency.

To make your own extract:

“A liquid extract can be made form the whole stevia leaves or from the green herbal stevia powder. Simply combine a measured portion of stevia leaves or herbal powder with pure USP grain alcohol (brandy or scotch will also do) and let the mixture sit for 24 hours. (7)

A pure water extract can be similarly prepared, but will not extract quite as much of the sweet glycosides as will the alcohol. (7) Water extracts have a limited shelf life, so should be stored in the refrigerator. (6)

Either liquid extract can be cooked down and concentrated into a syrup [at a simmer - do not boil].”(7)

Filter the liquid from the leaves or powder residue and dilute to taste using pure water. Note that the alcohol content can be reduced by very slowly heating (not boiling) the extract and allowing the alcohol to evaporate off. (7)

Stevia extract (powder)

The concentrated stevia extract tincture can also be dried and purified to produce a fine white powder containing the full spectrum of steviosides (unlike the commercial Rebiana sweeteners – Truvia and PureVia – and derived from stevia). 1 teaspoon of powdered extract is roughly equivalent to 1 cup of table sugar.

Although this is not something you can do in your own kitchen, it could be an entrepreneurial opportunity for an adventurous chemist.

Truvia and PureVia, sweeteners “made from stevia”

Rebiana (marketed as Truvia, PureVia by Coca-Cola and Pepsico, respectively) is a refined version of Rebaudioside A, one of the steviosides in stevia herb. This chemical is extracted, purified and crystallized. The purification process involves treating the extract with dubious chemicals including methanol (wood alcohol).

It is too new on the market to know if there are health concerns. Rebiana is also  bulked with sugar-like substances including sugar alcohols (erythritol, etc.) to give it the crystalline appearance of sugar, but that may have deleterious side effects.

Of all the artificial sweeteners, it is probably the safest. But why use this when real stevia is so much more natural?

Sources

Stevia.net (1) recommends the following mail-order sources of stevia transplats:

  • The herbal Advantage offers 2.25” pot size stevia plants ready for planting. (800) 753-9929; Rte 3, Box 93, Rogersville MO 65742
  • Richter’s Herbs offers 2.5” pots via courier. (905) 640-6677 or fax (905) 640-6641; 357 Highway 47, Goodwood, Ontario Canada L0C-1A0
  • Well Sweet Herb Farm offers 3” pot size. (908) 852-5390; 205 Mt. Bethel Road, Port Murray, NJ 07865.

Stevia seeds can be ordered from:

References

  1. Stevia.net: Growing Stevia (www.stevia.net/growingstevia.htm)
  2. The Tasteful Garden: Growing Stevia (www.tastefulgarden.com/Stevia.htm)
  3. Stevia Homestead: Growing Stevia Rebaudiana (stevia.homestead.com/grow.html)
  4. Starting Stevia from Seed  (prairieoakpublishing.com/SteviaSeedStarting.aspx
  5. Growing your own Stevia (prairieoakpublishing.com/GrowingStevia101.aspx)
  6. Choosing Stevia products for Recipes (prairieoakpublishing.com/ChoosingSteviaProducts.aspx
  7. Stevia.com: Questions & Answers About Stevia (www.stevia.com/Stevia_Article.aspx?Id=2269)

One Response to “Stevia: Growing, Harvesting, Drying, & Using this Sweetener”

  1. Jody Petitti says:

    Stevia is actually a wonderful sweets subsitute. It does not lead to tooth decay and best of all, it can not cause unhealthy weight and diabetes.

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