Stevia (Sweetleaf) Care At A Glance
- Perennial, evergreen herbs in frost-free zones, otherwise grow as annual.
- Easy to grow in organically rich, well-draining soils.
- Full to part sun.
- Water consistently and fertilize regularly to maximize foliage growth.
- Once mature, leaves can be harvested every few months to be processed for sweetener.
- Use fresh, sterile Seed Starting Mix free of fertilizer.
- Pre-moisten the mix and firm it into trays, cells, or peat pots.
- Pre-soak seeds for 8 hrs. (overnight) starting with warm (100°F) water in a teacup.
- After soaking, rinse seeds and sow immediately at 1/4-inch depth, making sure seeds make good seed-to-soil contact then water lightly.
- Place trays or pots onto a heat mat with consistent bottom heat of 75°-85°F and cover with a humidity dome or kitchen plastic wrap.
- In optimal conditions with consistent heat and moisture, seeds typically germinate in 7-14 days.
Planting Potted Indoor Plants
- Plants grow best in 12-inch terra-cotta pots, but any pot this size with adequate drainage holes can be used along with fresh, well-draining potting soil.
- After planting, the top of the root ball should be even with the soil level in the pot, leaving the crown at or just above the soil surface.
- Water thoroughly and place in direct sunlight.
- Water as needed, but do not allow the soil to dry out completely.
- Plants can be placed outdoors during warm months but do so only after the threat of frost has passed, then gradually transition them back into the house in late summer to early fall.
- In warmer climates, after the threat of frosts, harden plants off for 7-10 days prior to planting out.
- Dig a hole twice the size of the root ball and space multiple plants 1.5-2 feet apart.
- Amend the existing soil with a 50/50 blend of compost and aged manure.
- Plant at the same depth as the top of the root ball, even with the natural soil grade.
- Gently loosen tight or constricted roots prior to planting.
- Prevent competition from invasive weeds or grasses by mulching well around plants.
- Water new plants thoroughly and slowly to ensure all air pockets have been removed.
NOTE: For either planting situation, ensure plants have good drainage. Root rot can be a common issue in heavy or wet soils.
Stevia growers should know that plants grown for a sweetener should not be allowed to fully flower, since flowering rapidly diminishes Stevioside compounds responsible for their sweet flavor. However, the leaves contain the highest amount of Stevioside when the tiny, white flowers first appear. These flowers, borne in clusters at the end of each stem, should all be pinched off when they form. Since harvesting too many leaves at one time can be detrimental to plant health, planting several plants for consistent harvests is suggested.
- Allow plants to mature for one full growing season before the first harvest.
- Once mature, a few leaves can be harvested once every three months.
- Full-sized plants usually grow to 1-2 feet high and wide.
- The larger the plant, the more leaves can be harvested.
Fresh Stevia Leaves
Stevia leaves can be picked and used fresh from a stevia plant. This is their most natural state, as a freshly consumed herb.
- Chewing fresh leaves provides a lasting, but mildly sweet anise-like flavor.
- A single leaf can also give a sweet essence to hot or cold beverages.
- Drying and processing yield the highest Stevioside concentrations. (See below)
Tapping Into Sweetness
Once leaves have been harvested, they must be dried, then crushed.
- Drying can be accomplished using a dehydrator or spreading them on a screen.
- Provide good air circulation, in direct or indirect sun with modest heat.
- Drying times can vary but typically takes about 8-12 hours. The longer the drying takes, the lower the potential sweetness leaves have. Leaves not fully dried do not grind to powder as well.
- Once the leaves are sufficiently dried, then they must be crushed or ground to a fine powder. This can be done by hand with a mortar & pestle, coffee grinder, or special herb blender.
- After crushing, the powdered leaves are sieved, and the finest powder can then be stored in airtight containers for future use.
- Whole dried leaves can also be steeped as you would for any herbal tea.
Creating Concentrated Extracts
Many recipes can be found online or in specialty cookbooks for producing different forms of concentrated stevia extracts or syrups, by steeping then boiling the leaves in water or creating a mixture of distilled water and grain alcohol as you would for making homemade vanilla.