Many varieties of Crape Myrtle are dependable and mostly disease-free small trees or shrubs that thrive in hot humid summers. The late-season flowers are showy enough to compete with Hydrangeas and provide many weeks of color. The two main techniques to multiply your collection of Crape Myrtle are either by saving seeds and growing them in containers for a few years before planting in the garden or by taking semi-hardwood cuttings that will be ready to plant as soon as 3 months after roots begin to grow.
Although cuttings and seed saving are more advanced techniques for most gardeners, they are two skills that once perfected can be used on the vast majority of plants grown in a home garden.
Methods To Propagate Crape Myrtle
Most Crape Myrtle shrubs and trees are hybrid varieties bred to display the best traits such as disease resistance, flower head shape, growth habit, or any other regionally important characteristic. If you want to preserve a particular flower color or hardy growth habit, taking cuttings from Crape Myrtle ensures that the new plants have the exact genetic makeup of the parent.
Collecting and growing seeds from plants is a gamble on whether the genetics will come true in each seed. Don’t let that discourage you from starting hybrid plants from seed if you truly just want to “see what you get”. Most times the process is worth more than the finished product.
Be aware that it is very common for Crape Myrtle trees and shrubs to have a patent attached to their hybridization, making both commercial and private propagation illegal until the patent runs out. A little bit of research on the exact variety or cultivar you have will quickly reveal if it is still patent-protected or if it has expired.
A good rule of thumb is that most patents expire after 20 years, making the oldest and most well-known Crape Myrtle fair game for propagating.
What You Need To Propagate Crape Myrtle
Here are the materials that you need for both starting seeds or taking semi-hardwood cuttings of Crape Myrtle.
For cuttings: Semi-hardwood cuttings require consistent moisture, humidity, and warmth to strike roots successfully. A fast-draining but moisture-retentive mix of 50%perlite and 50% all-purpose potting mix is easy to use and keep on hand. Using 100% perlite is an even better media for starting Crape Myrtle cuttings as it allows for good drainage and airflow.
A one-gallon nursery pot will comfortably hold 5 to 8 cuttings. Use some sort of cover for the pot to act as a small greenhouse to keep condensation and humidity around the cuttings until the roots begin to show. This could be a clear plastic bag placed over one pot or a clear storage bin turned upside down to house a few pots at a time.
For seeds: Seeds need to be started in a bright, warm location indoors. Use a Grow light if you do not have a window with bright direct light (typically South or Southwest facing). A heat mat will help to speed up germination but is not necessary if the room you are using remains at 68 -75F consistently. A premixed, soilless seed starting mix is ideal for allowing the seeds to easily grow as they germinate, to retain moisture between waterings.
Seed-starting flats or individual 4-inch pots work to start a thin sowing of seeds until the first or second set of true leaves appear. After that individual plants should be moved to their own 4-6 inch pots, eventually working up to a one-gallon nursery container. No stratification or scarification is needed to prime Crape Myrtle seeds for germination. Use an all-purpose, peat-free potting mix when it is time to pot up the seedlings to their own containers.
Best Time To Propagate Crape Myrtle
For cuttings: Semi-hardwood cuttings can only be taken as the New Year’s stems harden during the summer. Non-flower producing stems are the only guarantee that the cuttings have enough energy to grow roots.
For seeds: Save the seeds from Crape Myrtle after they have finished flowering and the seeds have dried on the plant in the late summer or early fall. The dark brown seed pods are easy to pick and will contain many seeds. Store the dried seeds in a paper envelope and keep them in a cool dry and dark location until you are ready to sow the seeds.
Starting the seeds in late winter or very early spring may result in plants that are large enough to grow outdoors by the summer.
Steps To Propagate Crape Myrtle
The following propagation steps are for taking semi-hardwood cuttings. These steps are the same for softwood or hardwood cuttings and are good to master for growing a broad range of shrubs, trees, or perennial plants.
Step 1 - Prep your rooting container with pre-moistened perlite or potting mix/perlite. Fill the pot to within ½ inch of the top and gently firm down the potting media.
Step 2 - Take cuttings (with sharp and sterilized hand pruners) from the ends of stems that are not developing or have finished flowering. Cut 6-8 inches from the end of the stem, ensuring that at least 4 leaf joins are on the stem.
Step 3 - Carefully remove all but the top set of leaves from the stem. All of the exposed leaf nodes are potential sites for root growth and will be under the soil. If the top set of leaves are very large cut them down by half their size to reduce the amount of energy the cutting needs to keep them growing before roots appear.
Step 4 - Make a hole in the filled pot that goes to the bottom of the container and along the sidewall.
Step 5 - Dip the cut end of the semi-hardwood cutting in powdered rooting hormone. Using an Auxin powder helps roots develop faster in semi-hardwood and hardwood cuttings, reducing the chance that the cutting will rot by sitting too long in the pot.
Step 6 - Once all of the cuttings are in the pot gently tap the bottom of then pot to cover the stems and even out the starting media.
Step 7 - Place the pot in a seed-starting greenhouse dome or place a clear plastic bag over the top of the pot to preserve moisture and humidity around the cutting.
Step 8 - Place the pot in a warm location that has bright direct light. Check for watering of the starting media every few days and water the pot from the bottom when needed.
Caring For Young Crape Myrtle Cuttings
Roots will begin to appear at 4-6 weeks. Once roots begin to grow from the bottom of the pot, all of the cuttings can be gently teased apart and repotted into their own one-gallon containers to grow on. Use an all-purpose outdoor potting mix and make sure the containers have plenty of bottom drainage.
Keep the new plants watered consistently and feed them with a diluted liquid fertilizer once a month. The new plants should be acclimated to growing outdoors slowly over the course of a week or more and never placed in full sun while still growing in a container.
Sources:
“Crape Myrtle Culture”, University of Georgia Extension. www.extension.uga.edu
“Plant Patents”, North Carolina State Libraries. www.lib.ncsu.edu
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Author Robbin Small - Published 12-27-2024 |