How to Grow Leptospermum

Leptospermum is the botanical name of a genus of shrubs native to Australia and New Zealand. Although the common name for leptospermum is tea tree, it should not be confused with Melaleuca alternifolia, the source of medicinal tea tree oil. Shrubs within the genus range in height from 5 to 25 feet, but all species feature evergreen leaves and showy displays of pale pink or white flowers. Leptospermum is widely cultivated as an ornamental shrub within U.S. Department of Agriculture hardiness zones 9 to 11, where it prospers in a variety of soils as long as it is provided with full sun.

Things You'll Need

• Peat moss
• Vermiculite
• Horticultural sand
• 4-inch plastic pots
• Propagation heat mat
• Spray bottle
• Garden utility knife
• Rooting hormone
• Plastic bags

Instructions

Growing Leptospermum from Seed

1. Combine 3 parts milled peat moss and 2 parts vermiculite to create a suitable rooting mix for the leptospermum seeds. Mix the components until the peat moss is free of clumps and the vermiculite is evenly distributed.

2. Fill several 4-inch plastic pots with the soil mixture. Water the soil to a depth of 3 inches. Allow it to drain for 20 minutes before planting the seeds.

3. Mix the leptospermum seed with horticultural sand since the seed is extremely fine and difficult to evenly spread on its own. Combine equal parts seed and sand in a sealable plastic bag and shake it.

4. Spread 1/4 tsp. of the seed mixture over the soil in each pot. Press the seeds into the surface of the soil with the flat of your thumb. Sprinkle a small amount of peat moss over the top of the seeds.

5. Place the pots on a propagation heat mat set to 65 degrees Fahrenheit in a place with bright, indirect light. Test the soil moisture daily and apply 1/4 inch of water with a spray bottle when the soil feels dry to the touch.

6. Thin the seedlings once they reach 3 inches in height. Remove any seedlings with thin or weak stems. Keep no more than three seedlings in each pot.

7. Transplant the seedlings to individual pots when they are large enough to handle. Keep the pots on the heat mat and near a light source during the winter. Plant the saplings outdoors in a sunny, draining bed when they reach 10 inches in height.

Growing Leptospermum from Cuttings

1. Select several cuttings from a healthy leptospermum shrub. Choose new growth cuttings from the tip of the branch. Look for twigs with soft reddish bark and multiple leaf terminals.

2. Cut at a 45-degree angle 3 to 4 inches from the leafy tip of the twig. Cut a 1/4-inch long portion of bark from the end of the cutting to expose the vascular cambium. Place the cuttings in water until ready to pot them.

3. Combine equal parts milled peat moss, vermiculite and horticultural sand to create a soilless rooting medium. Fill one 4-inch plastic pot for each cutting. Apply water to 2 inches and allow the soil to drain for at least one-half hour before planting the cuttings.

4. Poke one hole in each pot of soil using a pencil or other long, slender implement. Make the hole to correspond to half the length of the cutting.

5. Dip the end of the cuttings in rooting hormone. Insert one cutting into each hole and gently firm the soil around them. Place a plastic bag over the top of each pot to hold moisture and heat near the foliage.

6. Apply 1/2-inch of water every five days, or as soon as the soil feels dry to the touch. Do not allow the soil to dry, but do not make it too wet.

7. Place the pots on a propagation heating mat set to 65 degrees Fahrenheit. Set the pots in a bright place with indirect sunlight. New growth will appear in 10 to 14 days.

8. Plant them outdoors in a sunny, draining bed the following spring when the soil temperature reaches 70 degrees Fahrenheit.

Tips & Warnings

• Gather mature leptospermum seed pods in late summer of their second growing season.

• Take leptospermum cuttings in July.

References

• "Trees for All Seasons: Broadleaved Evergreens for Temperate Climates"; Sean Hogan; 2008