Things You'll Need
Bowl or small bucket
70 percent isopropyl alcohol
6-inch plastic pot
Sterile, soil-less potting medium
3 or 4 plastic straws or 1/4-inch wooden dowels
Clear plastic bag
10-10-10 water-soluble fertilizer
Native to eastern Africa, the tamarind tree (Tamarindus indica) proves its worth in your yard with its wind-tolerant, shade-casting branches and evergreen foliage. This slow-growing, tropical tree reaches 90 feet tall and produces pale green leaves, yellow spring flowers and brown seed pods in the late spring and early summer. Hardy in U.S. Department of Agriculture plant hardiness zones 10 through 11, the tamarind requires full sun and fast-draining, slightly acidic soil. Tamarind trees are generally easy to grow from seed with the proper treatments and planting techniques.
Pour equal quantities of 70 percent isopropyl rubbing alcohol and water into a bowl or small bucket. Brush any clinging debris off the blades of a pair of pruning shears and a knife using a stiff-bristled brush. Submerge the blades of both tools in the alcohol solution. Let the tools soak for five minutes. Remove the blades from the solution and set them on a flat, clean surface to air-dry.
Select an undamaged tamarind pod without any blemishes. Grasp the bottom of the pod and cut through the top of its stalk, 1/4 inch below the tree branch, with the pruning shears. Repeat this process to collect as many seed pods as desired. Harvest the seed pods in the late spring or early summer, once they turn completely brown, feel plump and develop a hard yet brittle shell.
Lay the pods on a flat surface where they will not be disturbed, positioning them in direct sunlight. Let the pods sit for five to seven days to dry, turning them once every one to two days.
Break or cut the dried pods open with your hands or the sterilized knife. Fill a bowl three-quarters full of water. Dump the pods' contents into the bowl. Stir the seeds in the water with your fingers to remove any clinging pulp from their surfaces. Discard any floating seeds, because these will not germinate.
Pour the bowl's contents into a strainer. Pick out the seeds from the strainer, rinsing them off in running water. Place the seeds on a cutting board. Select one seed and cut off a sliver from one of its edges or nick it with a sterilized knife to create an opening in the seed coat, taking care to avoid damaging the seed. Repeat this process with each seed you wish to plant.
Rinse the bowl out to remove any clinging debris. Fill it three-quarters full of water. Place the cut seeds in the bowl. Set the bowl in an area with a constant temperature of 70 degrees Fahrenheit, positioning it in bright, indirect sunlight. Leave the seeds to soak for 24 hours.
Fill a 6-inch plastic pot with a sterile, soil-less potting medium to 1 1/2 inches below its top. Tamp the medium down to settle it. Add more medium to the pot, if needed, to attain the correct level. Prepare one pot for each tamarind tree you wish to grow.
Pull two to three seeds out of the bowl of water. Place the seeds on top of the medium in the pot's center. Position the seeds side by side in a circle. Cover the seeds with a 1/2-inch-deep layer of the potting medium, tamping it down lightly. Repeat this process to plant each prepared pot.
Pour water slowly from a watering can into the pot. Wait until the water drains completely down into the medium. Repeat this process two to three times to ensure that the medium becomes completely moist. Water each pot in the same way.
Insert the bottom 1 to 2 inches of a plastic straw or 1/4-inch wooden dowel into the medium. Position the straw or dowel against the interior of the pot's side. Insert two to three more straws or dowels into the pot in the same way, spacing them evenly around the pot's perimeter. Repeat with each pot.
Pull a clear plastic bag over the pot's top, stopping once the bag's top rests lightly on top of the straws or dowels. Wrap a rubber band around the pot, over the top of the bag's edges, to secure it in place. Cover each pot with one bag.
Place a heat mat on a flat surface in a room with a constant temperature of 70 F or warmer. Position the mat in bright, indirect sunlight. Turn the mat on, setting its temperature to 70 F. Place the pots on the mat.
Check the pots each day, looking for signs of moisture loss. Remove the bag and water the pot when the top 1/4 inch of medium becomes dry. Pour the water slowly into the pot to avoid washing the medium off the seeds. Replace the bag after watering. Watch for germination seven to 10 days after planting.
Remove the bag from the pot, and take the pot off the heat mat once the seedlings emerge from the medium.
Water the seedlings when the top 1 to 2 inches of soil become dry. Fertilize the seedlings once per week beginning when the plants reach a height of 3 to 4 inches or develop three to five leaves. Mix 1/2 teaspoon of 10-10-10 water-soluble fertilizer with 1 gallon water in a watering can. Pour the solution slowly into the pot, filling it and allowing the excess to drain.
Remove the weakest seedlings from each pot once the plants develop three to four leaves, leaving a single strong seedling. Cut the weakest seedlings' stems off at soil level using a knife or pruning shears.
Grow the tamarind trees indoors in pots in a sunny, south-facing window for at least one year before transplanting them outside.
Rotate the tamarind trees' pots one-quarter of a turn every five to seven days to promote straight, even growth.
Mature tamarind seeds remain viable on the tree for up to six months after they mature. Harvest the seeds at any point during that time.
Tamarind trees grown from seed may differ from the parent tree that produced the seeds due to open pollination.
Tamarind trees grown from seed may not produce flowers or fruit until they're 6 to 8 years old.
Always sterilize your pruning and cutting tools before and after use to prevent the spread of disease.
Only use pots that contain bottom drainage holes to allow the excess moisture to drain away from the seeds to help prevent them from rotting.
Never water the seeds or seedlings to the point that the medium becomes soggy or the pot holds standing water to prevent rot from developing. Always remove any standing water from the pot's drainage tray after watering.
- University of Florida IFAS Extension: Tamarindus Indica
- Floridata: Tamarindus Indica
- California Rare Fruit Growers: Tamarind
- Crops for the Future: The Tamarind Tree
- First Regional Workshop on Tropical Fruit Crops; Rafael Marte et al.
- The New York Botanical Garden Illustrated Encyclopedia of Horticulture, Vol. 10; Thomas H. Everett
- University of Florida IFAS Extension: Disinfecting Pruning Tools
- University of Minnesota Extension: Starting Seeds Indoors